Photoelectrochemical(PEC)energy conversion has emerged as a promising and efficient approach to sustainable energy harvesting and storage.By utilizing semiconductor photoelectrodes,PEC devices can harness solar energy...Photoelectrochemical(PEC)energy conversion has emerged as a promising and efficient approach to sustainable energy harvesting and storage.By utilizing semiconductor photoelectrodes,PEC devices can harness solar energy and drive electrochemical reactions such as water splitting or carbon dioxide(CO_(2))reduction to generate clean fuels and value-added chemicals.However,PEC energy conversion faces several challenges such as high overpotential,sluggish reaction kinetics,charge carrier recombination,and stability issues,which limit its practical implementation.Recently,significant research has been conducted to improve the overall conversion efficiency of PEC devices.One particularly promising approach is the use of cocatalysts,which involves introducing specific cocatalysts onto the photoelectrode surface to promote charge separation,improve reaction kinetics,and reduce the overpotential,thereby enhancing the overall performance of PEC energy conversion.This review provides a comprehensive overview of the recent developments in the earth-abundant cocatalysts for PEC water splitting and CO_(2) reduction.The main earth-abundant catalysts for the PEC water splitting include transition-metal dichalcogenide(TMD)-based materials,metal phosphides/carbides,and metal oxides/hydroxides.Meanwhile,PEC-CO_(2)RR was divided into C_(1) and C_(2+)based on the final product since various products could be produced,focusing on diverse earth-abundant materials-based cocatalysts.In addition,we provide and highlight key advancements achieved in the very recent reports on novel PEC system design engineering with cocatalysts.Finally,the current problems associated with PEC systems are discussed along with a suggested direction to overcome these obstacles.展开更多
Taking copper doped ZnS(ZnS:Cu)nanocrystals as the main body of photocatalyst,the influence of different base transition metal ions(M^(2+)=Ni^(2+),Co^(2+),Fe^(2+)and Cd^(2+))on photocatalytic CO_(2)reduction in inorga...Taking copper doped ZnS(ZnS:Cu)nanocrystals as the main body of photocatalyst,the influence of different base transition metal ions(M^(2+)=Ni^(2+),Co^(2+),Fe^(2+)and Cd^(2+))on photocatalytic CO_(2)reduction in inorganic reaction system is investigated.Confined single-atom Ni^(2+),Co^(2+),and Cd^(2+)sites were created via cation-exchange process and enhanced CO_(2)reduction,while Fe^(2+)suppressed the photocatalytic activity for both water and CO_(2)reduction.The modified ZnS:Cu photocatalysts(M/ZnS:Cu)demonstrated tunable product selectivity,with Ni^(2+)and Co^(2+)showing high selectivity for syngas production and Cd^(2+)displaying remarkable formate selectivity.DFT calculations indicated favorable H adsorption free energy on Ni^(2+)and Co^(2+)sites,promoting the hydrogen evolution reaction.The selectivity of CO_(2)reduction products was found to be sensitive to the initial intermediate adsorption states.*COOH formed on Ni^(2+)and Co^(2+)while*OCHO formed on Cd^(2+),favoring the production of CO and HCOOH as the main products,respectively.This work provides valuable insights for developing efficient solar-to-fuel platforms with controlled CO_(2)reduction selectivity.展开更多
Photocatalytic solar energy conversion to hydrogen is sustainable and attractive for addressing the global energy and environmental issue. Herein, a novel photocatalytic system (NiS/Ni3S4 cocatalysts modified mesoporo...Photocatalytic solar energy conversion to hydrogen is sustainable and attractive for addressing the global energy and environmental issue. Herein, a novel photocatalytic system (NiS/Ni3S4 cocatalysts modified mesoporous TiO2) with superior photocatalytic hydrogen evolution capability through the synergistic impact of NiS/Ni3S4 (NiSx) cocatalyst and efficient hole scavenger has been demonstrated. The photocatalytic hydrogen evolution of TiO2-NiSx hybrids with the different content of NiSx and upon different organic hole scavengers was both investigated. The hybrid of TiO2 decorated with 3%(mole ratio of Ni^2+) NiSx cocatalyst in methanol solution showed the optimal photocatalytic hydrogen evolution rate of 981.59 μmol h^-1 g^-1 which was about 20 times higher than that of bare mesoporous TiO2. Our results suggested that the boosted hydrogen production performance is attributed to both the improved photoinduced electrons migration between NiS and Ni3S4 in cocatalyst and the high hole captured efficiency by hole scavengers of methanol.展开更多
Conversion of carbon dioxide(CO_(2))into valuable chemicals and renewable fuels via photocatalysis represents an eco-friendly route to achieve the goal of carbon neutralization.Although various types of semiconductor ...Conversion of carbon dioxide(CO_(2))into valuable chemicals and renewable fuels via photocatalysis represents an eco-friendly route to achieve the goal of carbon neutralization.Although various types of semiconductor materials have been intensively explored,some severe issues,such as rapid charge recombination and sluggish redox reaction kinetics,remain.In this regard,cocatalyst modifi cation by trapping charges and boosting surface reactions is one of the most effi cient strategies to improve the effi ciency of semiconductor photocatalysts.This review focuses on recent advances in CO_(2)photoreduction over costeff ective and earth-abundant cobalt(Co)-based cocatalysts,which are competitive candidates of noble metals for practical applications.First,the functions of Co-based cocatalysts for promoting photocatalytic CO_(2)reduction are briefl y discussed.Then,diff erent kinds of Co-based cocatalysts,including cobalt oxides and hydroxides,cobalt nitrides and phosphides,cobalt sulfi des and selenides,Co single-atom,and Co-based metal–organic frameworks(MOFs),are summarized.The underlying mechanisms of these Co-based cocatalysts for facilitating CO_(2)adsorption–activation,boosting charge separation,and modulating intermediate formation are discussed in detail based on experimental characterizations and density functional theory calculations.In addition,the suppression of the competing hydrogen evolution reaction using Co-based cocatalysts to promote the product selectivity of CO_(2)reduction is highlighted in some selected examples.Finally,the challenges and future perspectives on constructing more effi cient Co-based cocatalysts for practical applications are proposed.展开更多
Photocatalysis, which performed under mild conditions by utilizing solar energy, has become a desirable technology to convert methane into highly valuable chemicals, such as methanol, ethane, and other hydrocarbons. H...Photocatalysis, which performed under mild conditions by utilizing solar energy, has become a desirable technology to convert methane into highly valuable chemicals, such as methanol, ethane, and other hydrocarbons. However, pristine photocatalysts still suffer from the low utilization efficiency of solar light and the high recombination rate of photogenerated charge carriers, which exhibit the low activity and selectivity for photocatalytic methane conversion. Loading cocatalysts on photocatalysts is an attractive strategy to manipulate the products' yield and selectivity of photocatalytic methane conversion due to the enhanced charge carrier separation efficiency, extended light absorption and promoted reactant adsorption/desorption kinetics. This review discusses the recent achievements of the cocatalysts for photocatalytic methane conversion reactions. Moreover, the challenges and perspectives for the development of efficient cocatalysts are presented. This review provides considerable guidelines for the design and construction of efficient cocatalysts for photocatalytic methane conversion reactions.展开更多
Owing to their unique physicochemical,optical and electrical properties,two-dimensional(2D)MoS_(2) cocatalysts have been widely applied in designing and developing highly efficient composite photocatalysts for hydroge...Owing to their unique physicochemical,optical and electrical properties,two-dimensional(2D)MoS_(2) cocatalysts have been widely applied in designing and developing highly efficient composite photocatalysts for hydrogen generation under suitable light irradiation.In this review,we first elaborated on the fundamental aspects of 2D MoS_(2) cocatalysts to include the structural design principles,synthesis strategies,strengths and challenges.Subsequently,we thoroughly highlighted and discussed the modification strategies of 2D MoS_(2) H2-evolution cocatalysts,including doping heteroatoms(e.g.metals,non-metals,and co-doping),designing interfacial coupling morphologies,controlling the physical properties(e.g.thickness,size,structural defects or pores),exposing the reactive facets or edge sites,constructing cocatalyst heterojunctions,engineering the interfacial bonds and confinement effects.In the future,the forefront challenges in understanding and in precise controlling of the active sites at molecular level or atomic level should be carefully studied,while various potential mechanisms of photogenerated-electrons interactions should be proposed.The applications of MoS_(2) cocatalyst in the overall water splitting are also expected.This review may offer new inspiration for designing and constructing novel and efficient MoS_(2)-based composite photocatalysts for highly efficient photocatalytic hydrogen evolution.展开更多
Photocatalytic Hproduction from water splitting has a promising prospect for alleviating energy and environmental issues.However,the fast recombination of photogenerated charge carriers limits the photocatalytic effic...Photocatalytic Hproduction from water splitting has a promising prospect for alleviating energy and environmental issues.However,the fast recombination of photogenerated charge carriers limits the photocatalytic efficiency and its practical application.Cocatalyst engineering is an effective strategy to spatially separate photogenerated charge carriers.In this work,noble-metal-free MoSand CoOcocatalysts are loaded on CdS nanorods by a two-step photodeposition method.The MoSfunctions as the reduction cocatalyst to trap electrons and Co Oas the oxidation cocatalyst to trap holes.Transmission electron microscopy(TEM),inductively coupled plasma(ICP),X-ray photoelectron spectroscopy(XPS)and MottSchottky results demonstrate the effectiveness of photodeposition for loading MoSand CoOdual cocatalysts on CdS and their impact on the photochemical properties.The optimized CdS-MoS-CoOcomposite exhibits a high photocatalytic H-production rate of 7.4 mmol g^(-1)h^(-1)and an apparent quantum efficiency(QE)of 7.6%at 420 nm.Further analysis on time-resolved photoluminescence(TRPL)indicates that the introduction of dual cocatalysts greatly prolongs the lifetime of photogenerated charge carriers and deceases the charge recombination rates,consequently leading to superior photocatalytic H-production performance.This work provides a facile and effective strategy for the construction of highly efficient dual-cocatalyst-modified CdS photocatalyst for high-performance photocatalytic Hproduction.展开更多
Efficient photocatalytic reduction of CO_(2) to high-calorific-value CH4,an ideal target product,is a blueprint for C_(1)industry relevance and carbon neutrality,but it also faces great challenges.Herein,we demonstrat...Efficient photocatalytic reduction of CO_(2) to high-calorific-value CH4,an ideal target product,is a blueprint for C_(1)industry relevance and carbon neutrality,but it also faces great challenges.Herein,we demonstrate unprecedented hybrid SiC photocatalysts modified by Fe-based cocatalyst,which are prepared via a facile impregnation-reduction method,featuring an optimized local electronic structure.It exhibits a superior photocatalytic carbon-based products yield of 30.0μmol g^(−1) h^(−1) and achieves a record CH_(4) selectivity of up to 94.3%,which highlights the effectiveness of electron-rich Fe cocatalyst for boosting photocatalytic performance and selectivity.Specifically,the synergistic effects of directional migration of photogenerated electrons and strongπ-back bonding on low-valence Fe effectively strengthen the adsorption and activation of reactants and intermediates in the CO_(2)→CH_(4) pathway.This study inspires an effective strategy for enhancing the multielectron reduction capacity of semiconductor photocatalysts with low-cost Fe instead of noble metals as cocatalysts.展开更多
TiO2 photoanodes have aroused intensive research interest in photoelectrochemical (PEC) water splitting. However, they still suffer from poor electron-hole separation and sluggish oxygen evolution dynamics, leading ...TiO2 photoanodes have aroused intensive research interest in photoelectrochemical (PEC) water splitting. However, they still suffer from poor electron-hole separation and sluggish oxygen evolution dynamics, leading to the low photoconversion efficiency and limiting commercial application. Here, we designed and fabricated novel ternary non-noble metal carbonate hydroxide (ZNC-CH) nanosheet cocatalysts and integrated them with TiO2 nanorod arrays as highly efficient photoanodes of PEC cells. Compared with the pristine TiO2, the photocurrent of photoanode with the optimal amount of ZNC-CH represents 3.2 times enhancement, and the onset potential is shifted toward the negative potential direction of 62 mV, The remarkable enhancement is attributed to the suppressed carrier recombination and enhanced charge transfer efficiency at the interface of TiO2, ZNC-CH and electrolyte, which is closely related to the zinc elements modulated intrinsic activity of catalysts. Our results demonstrate that the introduction of multimetallic ZNC-CH cocatalysts onto photoanodes is a promising strategy to improve the PEC efficiency.展开更多
Photocatalytic reduction of CO2 into high value-added CH4 is a promising solution for energy and environmental crises. Integrating semiconductors with cocatalysts can improve the activities for photocatalytic CO2 redu...Photocatalytic reduction of CO2 into high value-added CH4 is a promising solution for energy and environmental crises. Integrating semiconductors with cocatalysts can improve the activities for photocatalytic CO2 reduction; however, most metal cocatalysts mainly produce CO and H2. Herein, we report a cocatalyst hydridation approach for significantly enhancing the photocatalytic reduction of CO2 into CH4. Hydriding Pd cocatalysts into PdH0.43 played a dual role in performance enhancement. As revealed by our isotopic labeling experiments, the PdH0.43 hydride cocatalysts reduced H2 evolution, which suppressed the H2 production and facilitated the conversion of the CO intermediate into the final product: CH4. Meanwhile, hydridation promoted the electron trapping on the cocatalysts, improving the charge separation. This approach increased the photocatalytic selectivity in CH4 production from 3.2% to 63.6% on Pd{100} and from 15.6% to 73.4% on Pd{111}. The results provide insights into photocatalytic mechanism studies and introduce new opportunities for designing materials towards photocatalytic CO2 conversion.展开更多
2D-layered graphitic carbon nitride(g-C_(3)N_(4))is regarded as a great prospect as a photocatalyst for H_(2)generation.However,g-C_(3)N_(4)’s photocatalytic hydrogen evolution(HER)activity is significantly restricte...2D-layered graphitic carbon nitride(g-C_(3)N_(4))is regarded as a great prospect as a photocatalyst for H_(2)generation.However,g-C_(3)N_(4)’s photocatalytic hydrogen evolution(HER)activity is significantly restricted by the recombination of photocarriers.We find that cobalt sulfide(CoS_(2))as a cocatalyst can promote g-C_(3)N_(4)nanosheets(NSs)to realize very efficient photocatalytic H_(2)generation.The prepared CoS_(2)/g-C_(3)N_(4)hybrids display highly boosted photocatalytic H_(2)generation performance and outstanding cycle stability.The optimized 7%-CoS_(2)/g-C_(3)N_(4)hybrids show a much improved photocatalytic H_(2)generation rate of 36.2μmol-1h-1,which is about 180 times as much as bare g-C_(3)N_(4)(0.2μmol-1h-1).In addition,the apparent quantum efficiency(AQE)of all the samples was computed under light atλ=370 nm,in which the AQE of 7%-CoS_(2)/g-C_(3)N_(4)hybrids is up to 5.72%.The experimental data and the DFT calculation suggest that the CoS_(2)/g-C_(3)N_(4)hybrid’s excellent HER activity is attributable to the lower overpotential and the smaller Co-H bond activation energy for HER.Accordingly,the CoS_(2)cocatalyst loading effectively boosts the photocatalytic performance of g-C_(3)N_(4)for H_(2)evolution.The project promotes fast development of high-efficiency photocatalysts and low-cost for photocatalytic H_(2)generation.展开更多
The global adoption of efficient sustainable energy sources is a crucial step toward meeting energy demands while achieving carbon emission reduction targets.Solar energy has become a clean and cost-competitive altern...The global adoption of efficient sustainable energy sources is a crucial step toward meeting energy demands while achieving carbon emission reduction targets.Solar energy has become a clean and cost-competitive alternative to traditional fossil fuels,but the intermittent nature of sunlight results in challenges associated with energy storage and transport.Photocatalytic carbon dioxide reduction intends to mimic natural photosynthesis for utilizing sunlight to chemically convert water and CO_(2) into fuels.In this process,the solar energy is captured and stored in fuels,so-called solar fuels,for widespread on-demand use.Heterogeneous solar fuel production systems are multi-component,comprising light-harvesting(photosensitizer)and catalytic(cocatalyst)units.Cocatalysts are indispensable for photocatalytic CO_(2) reduction systems,which promote charge carrier separation and transport,reduce the reaction activation energy,and alter the reaction route,thereby enhancing the activity and selectivity of the photocatalytic reactions.This review presents a comprehensive summary of the recent advancements in cocatalysts for photocatalytic CO_(2) reduction reaction(CO_(2)RR),with the purpose of providing new insights and guidance to the field with regard to research directions and best practices.We summarize how various cocatalysts including inorganic nanoparticles,metal complexes,enzymes,and bacteria can be combined with semiconductor photosensitizer for light-driven photocatalytic CO_(2)RR.Side-by-side comparisons reveal the strengths and limitations of each kind of cocatalysts and how lessons extracted from studying natural photosynthetic systems can be applied to investigations of artificial photosynthesis,presenting an outlook discussing possible future concepts for a more effective photocatalytic CO_(2) reduction process.展开更多
Photoelectrochemical(PEC)water splitting using semiconductors offers a promising way to convert renewable solar energy to clean hydrogen fuels.However,due to the sluggish reaction kinetics of water oxidation,significa...Photoelectrochemical(PEC)water splitting using semiconductors offers a promising way to convert renewable solar energy to clean hydrogen fuels.However,due to the sluggish reaction kinetics of water oxidation,significant charge recombination occurred at the photoanode/electrolyte interface and cause decrease of its PEC performance.To reduce the surface recombination,we deposit different transition metal complexes on BiVO4 nanocone arrays by a versatile light driven in-situ two electrode photodeposition approach without applied bias.Conformal cobalt phosphate“Co-Pi”,nickel borate“Ni-Bi”and manganese phosphate“Mn-Pi”complexes were deposited on BiVO4 nanocone arrays to form core-shell structure photoanode,all of which lead to enhanced photoelectrochemical performance.The photocurrent of the Co-Pi/BiVO4 photoanode under front-side illumination for 5 min is increased by 4 folds comparing to that of bare BiVO4 photoanode at 0.6 V vs.RHE,reaching a hole transfer efficiency as high as 94.5%at 1.23 V vs.RHE.The proposed photodeposition strategy is simple and efficient,and can be extended to deposite cocatalyst on other semiconductors with a valence band edge located at a potential more positive than the oxidation potential of transition metal ion in the cocatalyst.展开更多
Spatially isolated oxidation and reduction cocatalysts on a semiconductor can realize efficient charge separation and thereby lead to increased photocatalytic hydrogen generation. However, the effective preparation of...Spatially isolated oxidation and reduction cocatalysts on a semiconductor can realize efficient charge separation and thereby lead to increased photocatalytic hydrogen generation. However, the effective preparation of such photocatalysts has proven challenging.Herein, we report the facile synthesis of a novel noblemetal-free CdS/MoS/CoPi ternary photocatalyst via a visible light-induced synthesis route, in which MoSreduction cocatalysts were precisely grown on the two terminals of CdS nanorods, while CoPi oxidation cocatalysts were preferentially anchored onto the sidewalls of CdS nanorods. Such spatially isolated MoSand CoPi redox cocatalysts endow CdS nanorods with a rapid charge separation, which enhances their hydrogen generation activity. The CdS/MoS/CoPi photocatalyst with optimized CoPi amount achieves the highest Hgeneration rate of 206 μmol/h, which is 21 and 2 times higher than that achieved by using CdS alone(9.7 μmol/h) and CdS/MoS(105 μmol/h), respectively. The present work highlights the effectiveness of the spatial isolation of reduction and oxidation sites for efficient charge separation and thereby provides a promising strategy for the preparation of highly active photocatalysts.展开更多
TiO_(2) has been considered as an ideal photocatalyst for water splitting.However,narrow light absorbance,low charge separation efficiency,and rare surface active sites lead to the low photocatalytic efficiency of TiO...TiO_(2) has been considered as an ideal photocatalyst for water splitting.However,narrow light absorbance,low charge separation efficiency,and rare surface active sites lead to the low photocatalytic efficiency of TiO_(2).Although extensive research attempted to improve the situation,there is still lack of method for constructing high active and noble-metal-free TiO_(2) photocatalyst for H_(2) evolution reactions(HER).In this work,we loaded single atomic(SA)Ni(or Co)on the surface of anatase TiO_(2)(TiO_(2)(A))nanosheets by an isolation strategy.Ethylene diamine tetraacetic acid and ethylene glycol(EDTA-EG)compounds were used to chelate metal ions in solution and form carbon quantum dots in the following thermal treatment to isolate the metal ions on surface of TiO_(2)(A).The prepared Ni SA/TiO_(2)(A)catalyst owned a“skin wrapped body”structure with in-situ formed twodimensional(2D)heterojunction facilitating the fast electron transfer.As a result,the Ni SA/TiO_(2)(A)catalyst showed a high H_(2) evolution rate of 2,900μmol·g−1·h−1.This work provides an isolation strategy for constructing promising single-atom metal catalyst for photocatalysis and beyond.展开更多
Photocatalytic water splitting by semiconductors is a promising technology to produce clean H_(2) fuel,but the efficiency is restrained seriously by the high overpotential of the H_(2)-evolution reaction together with...Photocatalytic water splitting by semiconductors is a promising technology to produce clean H_(2) fuel,but the efficiency is restrained seriously by the high overpotential of the H_(2)-evolution reaction together with the high recombination rate of photoinduced charges.To enhance H_(2) production,it is highly desirable yet challenging to explore an efficient reductive cocatalyst and place it precisely on the right sites of the photocatalyst surface to work the proton reduction reaction exclusively.Herein,the metalloid NixP cocatalyst is exactly positioned on the Z-scheme Cd_(0.5)Zn_(0.5)S/NiTiO_(3)(CZS/NTO)heterostructure through a facile photodeposition strategy,which renders the cocatalyst form solely at the electron-collecting locations.It is revealed that the directional transfer of photoexcited electrons from Cd_(0.5)Zn_(0.5)S to Ni_(x)P suppresses the quenching of charge carriers.Under visible light,the CZS/NTO hybrid loaded with the Ni_(x)P cocatalyst exhibits an optimal H_(2) yield rate of 1103μmol h^(-1)(i.e.,27.57 mmol h^(-1)g^(-1)),which is about twofold of pristine CZS/NTO and comparable to the counterpart deposited with the Pt cocatalyst.Besides,the high apparent quantum yield(AQY)of 56%is reached at 400 nm.Further,the mechanisms of the cocatalyst formation and the H2 generation reaction are discussed in detail.展开更多
Photocatalytic solar to energy conversion is considered an attractive approach for overcoming energy crises and environmental concerns.Recently,titanium carbide(Ti_(3)C_(2))MXenes have been recognized as promising coc...Photocatalytic solar to energy conversion is considered an attractive approach for overcoming energy crises and environmental concerns.Recently,titanium carbide(Ti_(3)C_(2))MXenes have been recognized as promising cocatalysts based on their metallic conductivity,excessive active reaction sites,and enlarged surface area.The current review focuses on the properties and applications of Ti_(3)C_(2)MXenes useful in the field of photocatalysis.More specifically,surface modification of Ti_(3)C_(2)MXenes by varying synthesis parameters to get pure materials and also composites with the role of functional groups towards solar energy conversion applications is highlighted in this review.The effect of etching and oxidizing pathways to get an efficient cocatalyst has been discussed in detail.Considering the significant effect of parameters,optimum synthesis conditions such as etchant type,concentration,time and type of intercalant in both the Ti_(3)C_(2)synthesis approaches for improved photoactivity are discussed.Additionally,the surface modification of Ti_(3)C_(2)through oxidation for TiO2growth on its surface is deliberated with a detailed discussion on etchant type,concentration,etching time,and environmental factors.The optimum oxidation condition,including temperature,time,and environment for thermal treatment of Ti_(3)C_(2),were also included.Lastly,the review summarizes the conclusion and future perspectives for solar energy conversion applications.展开更多
AgCl/Ti_(3)C_(2)@TiO_(2)ternary composites were prepared to form a heterojunction structure between AgCl and TiO_(2)and introduce Ti3C2 as a cocatalyst.The as-prepared AgCl/Ti_(3)C_(2)@TiO_(2)composites showed higher ...AgCl/Ti_(3)C_(2)@TiO_(2)ternary composites were prepared to form a heterojunction structure between AgCl and TiO_(2)and introduce Ti3C2 as a cocatalyst.The as-prepared AgCl/Ti_(3)C_(2)@TiO_(2)composites showed higher photocatalytic activity than pure AgCl and Ti_(3)C_(2)@TiO_(2)for photooxidation of a 1,4-dihydropyridine derivative(1,4-DHP)and tetracycline hydrochloride(TCH)under visible light irradiation(λ>400 nm).The photocatalytic activity of AgCl/Ti_(3)C_(2)@TiO_(2)composites depended on Ti_(3)C_(2)@TiO_(2)content,and the catalytic activity of the optimized samples were 6.9 times higher than that of pure AgCl for 1,4-DHP photodehydrogenation and 7.3 times higher than that of Ti_(3)C_(2)@TiO_(2)for TCH photooxidation.The increased photocatalytic activity was due to the formation of a heterojunction structure between AgCl and TiO_(2)and the introduction of Ti3C2 as a cocatalyst,which lowered the internal resistance,sped up the charge transfer,and increased the separation efficiency of photogenerated carries.Photogenerated holes and superoxide radical anions were the major active species in the photocatalytic process.展开更多
In the semiconductor-based photocatalysts for overall water splitting, loading proper cocatalysts play a crucial role in enhancing the photocatalytic activity. In this work, we have chosen Ni_n/α-Ga_2O_3 as a model a...In the semiconductor-based photocatalysts for overall water splitting, loading proper cocatalysts play a crucial role in enhancing the photocatalytic activity. In this work, we have chosen Ni_n/α-Ga_2O_3 as a model and provided detailed density functional theory calculations to investigate the function of cocatalysts in hydrogen evolution reaction(HER). We have studied the formation and stability of Ni_n(n = 1–4) cluster on two stable surfaces of α-Ga_2O_3(001) and(012). In a Ni_n/α-Ga_2O_3 system, as the Ni 3d states well overlap with O and Ga states, the excited electrons transferred from Ga to Ni may participate in HER. We theoretically predict that introduction of Nincluster on(012) surface can elevate the Fermi level toward the conduction band, which is favorable for the occurrence of HER. Electrochemical computations are used to explore the mechanism of HER. It is found that, in most of Ni_n/α-Ga_2O_3 systems, the active sites of HER are on Ni_n clusters. Loading Ni_n clusters not only importantly reduces the Gibbs free energy of HER but also improves the reaction activity of surface O and Ga sites in HER. Our calculations reasonably explain the experimental observation on significant enhancement of activity for generating hydrogen after loading nickel oxide cocatalysts.展开更多
Cocatalysts play important roles in improving the activity and stability of most photocatalysts.It is of great significance to develop economical,efficient and stable cocatalysts.Herein,using Na2CoFe(CN)6 complex as p...Cocatalysts play important roles in improving the activity and stability of most photocatalysts.It is of great significance to develop economical,efficient and stable cocatalysts.Herein,using Na2CoFe(CN)6 complex as precursor,a novel noble-metal-free FeCo@NGC cocatalyst(nano-FeCo alloy@N-doped graphitized carbon) is fabricated by a simple pyrolysis method.Coupling with g-C3 N4, the optimal FeCo@NGC/g-C3N4 receives a boosted visible light driven photocatalytic H2 evolution rate of 42.2 μmol h-1, which is even higher than that of 1.0 wt% Pt modified g-C3N4 photocatalyst.Based on the results of density functional theory(DFT) calculations and practical experiment measurements,such outstanding photocatalytic performance of FeCo@NGC/g-C3N4 is mainly attributed to two aspects.One is the accelerated charge transfer behavior,induced by a photogene rated electrons secondary transfer performance on the surface of FeCo alloy nanoparticles.The other is related to the adjustment of H adsorption energy(approaching the standard hydrogen electrode potential) by the presence of external NGC thin layer.Both factors play key roles in the H2 evolution reaction.Such outstanding performance highlights an enormous potential of developing noble-metal-free bimetallic nano-alloy as inexpensive and efficient cocatalysts for solar applications.展开更多
基金supported by the National Research Foundation of Korea (NRF)funded by the Korean government (2021R1A4A3027878,2022M3H4A1A01012712)。
文摘Photoelectrochemical(PEC)energy conversion has emerged as a promising and efficient approach to sustainable energy harvesting and storage.By utilizing semiconductor photoelectrodes,PEC devices can harness solar energy and drive electrochemical reactions such as water splitting or carbon dioxide(CO_(2))reduction to generate clean fuels and value-added chemicals.However,PEC energy conversion faces several challenges such as high overpotential,sluggish reaction kinetics,charge carrier recombination,and stability issues,which limit its practical implementation.Recently,significant research has been conducted to improve the overall conversion efficiency of PEC devices.One particularly promising approach is the use of cocatalysts,which involves introducing specific cocatalysts onto the photoelectrode surface to promote charge separation,improve reaction kinetics,and reduce the overpotential,thereby enhancing the overall performance of PEC energy conversion.This review provides a comprehensive overview of the recent developments in the earth-abundant cocatalysts for PEC water splitting and CO_(2) reduction.The main earth-abundant catalysts for the PEC water splitting include transition-metal dichalcogenide(TMD)-based materials,metal phosphides/carbides,and metal oxides/hydroxides.Meanwhile,PEC-CO_(2)RR was divided into C_(1) and C_(2+)based on the final product since various products could be produced,focusing on diverse earth-abundant materials-based cocatalysts.In addition,we provide and highlight key advancements achieved in the very recent reports on novel PEC system design engineering with cocatalysts.Finally,the current problems associated with PEC systems are discussed along with a suggested direction to overcome these obstacles.
基金financial support from the Tangshan Talent Funding Project(A202202007)the National Natural Science Foundation of China(21703065)+3 种基金the Natural Science Foundation of Hebei Province(B2018209267)the World Premier International Research Center Initiative(WPI Initiative)on Materials Nanoarchitectonics(MANA),the MEXT(Japan)the Photoexcitonix Project in Hokkaido Universitythe JSPS KAKENHI(Grant Number JP18H02065)。
文摘Taking copper doped ZnS(ZnS:Cu)nanocrystals as the main body of photocatalyst,the influence of different base transition metal ions(M^(2+)=Ni^(2+),Co^(2+),Fe^(2+)and Cd^(2+))on photocatalytic CO_(2)reduction in inorganic reaction system is investigated.Confined single-atom Ni^(2+),Co^(2+),and Cd^(2+)sites were created via cation-exchange process and enhanced CO_(2)reduction,while Fe^(2+)suppressed the photocatalytic activity for both water and CO_(2)reduction.The modified ZnS:Cu photocatalysts(M/ZnS:Cu)demonstrated tunable product selectivity,with Ni^(2+)and Co^(2+)showing high selectivity for syngas production and Cd^(2+)displaying remarkable formate selectivity.DFT calculations indicated favorable H adsorption free energy on Ni^(2+)and Co^(2+)sites,promoting the hydrogen evolution reaction.The selectivity of CO_(2)reduction products was found to be sensitive to the initial intermediate adsorption states.*COOH formed on Ni^(2+)and Co^(2+)while*OCHO formed on Cd^(2+),favoring the production of CO and HCOOH as the main products,respectively.This work provides valuable insights for developing efficient solar-to-fuel platforms with controlled CO_(2)reduction selectivity.
基金the National Natural Science Foundation of China(21501137)the Hubei Natural Science Foundation for financial support(2018CFB680)Support from the Australian Research Council(ARC)through ARC Discovery projects(DP130102699,DP 130102274,DP160102627)
文摘Photocatalytic solar energy conversion to hydrogen is sustainable and attractive for addressing the global energy and environmental issue. Herein, a novel photocatalytic system (NiS/Ni3S4 cocatalysts modified mesoporous TiO2) with superior photocatalytic hydrogen evolution capability through the synergistic impact of NiS/Ni3S4 (NiSx) cocatalyst and efficient hole scavenger has been demonstrated. The photocatalytic hydrogen evolution of TiO2-NiSx hybrids with the different content of NiSx and upon different organic hole scavengers was both investigated. The hybrid of TiO2 decorated with 3%(mole ratio of Ni^2+) NiSx cocatalyst in methanol solution showed the optimal photocatalytic hydrogen evolution rate of 981.59 μmol h^-1 g^-1 which was about 20 times higher than that of bare mesoporous TiO2. Our results suggested that the boosted hydrogen production performance is attributed to both the improved photoinduced electrons migration between NiS and Ni3S4 in cocatalyst and the high hole captured efficiency by hole scavengers of methanol.
基金supported by the National Natural Science Foundation of China(Nos.21905049,22178057)the Natural Science Foundation of Fujian Province(Nos.2020J01201,2021J01197)+1 种基金the Research Foundation of the Academy of Carbon Neutrality of Fujian Normal University(TZH2022-07)the Award Program for Minjiang Scholar Professorship。
文摘Conversion of carbon dioxide(CO_(2))into valuable chemicals and renewable fuels via photocatalysis represents an eco-friendly route to achieve the goal of carbon neutralization.Although various types of semiconductor materials have been intensively explored,some severe issues,such as rapid charge recombination and sluggish redox reaction kinetics,remain.In this regard,cocatalyst modifi cation by trapping charges and boosting surface reactions is one of the most effi cient strategies to improve the effi ciency of semiconductor photocatalysts.This review focuses on recent advances in CO_(2)photoreduction over costeff ective and earth-abundant cobalt(Co)-based cocatalysts,which are competitive candidates of noble metals for practical applications.First,the functions of Co-based cocatalysts for promoting photocatalytic CO_(2)reduction are briefl y discussed.Then,diff erent kinds of Co-based cocatalysts,including cobalt oxides and hydroxides,cobalt nitrides and phosphides,cobalt sulfi des and selenides,Co single-atom,and Co-based metal–organic frameworks(MOFs),are summarized.The underlying mechanisms of these Co-based cocatalysts for facilitating CO_(2)adsorption–activation,boosting charge separation,and modulating intermediate formation are discussed in detail based on experimental characterizations and density functional theory calculations.In addition,the suppression of the competing hydrogen evolution reaction using Co-based cocatalysts to promote the product selectivity of CO_(2)reduction is highlighted in some selected examples.Finally,the challenges and future perspectives on constructing more effi cient Co-based cocatalysts for practical applications are proposed.
基金financially supported from the National Natural Science Foundation of China (22209084)the Yongjiang Talent Project (2021A-142-G)+2 种基金the Natural Science Foundation of Ningbo (2021J066)the starting-up funding of Ningbo University (422109273)K.C.Wong Magna Fund in Ningbo University。
文摘Photocatalysis, which performed under mild conditions by utilizing solar energy, has become a desirable technology to convert methane into highly valuable chemicals, such as methanol, ethane, and other hydrocarbons. However, pristine photocatalysts still suffer from the low utilization efficiency of solar light and the high recombination rate of photogenerated charge carriers, which exhibit the low activity and selectivity for photocatalytic methane conversion. Loading cocatalysts on photocatalysts is an attractive strategy to manipulate the products' yield and selectivity of photocatalytic methane conversion due to the enhanced charge carrier separation efficiency, extended light absorption and promoted reactant adsorption/desorption kinetics. This review discusses the recent achievements of the cocatalysts for photocatalytic methane conversion reactions. Moreover, the challenges and perspectives for the development of efficient cocatalysts are presented. This review provides considerable guidelines for the design and construction of efficient cocatalysts for photocatalytic methane conversion reactions.
基金the National Natural Science Foundation of China(Nos.21975084 and 51672089)the Guangdong Provincial Applied Science and Technology Research and Development Program(No.2017B020238005)+2 种基金the Ding Ying Talent Project of South China Agricultural University for their supportthe Hong Kong Research Grant Council(RGC)General Research Fund(No.GRF1305419)for financial supportthe National Natural Science Foundation of China(Nos.51972287 and 51502269)。
文摘Owing to their unique physicochemical,optical and electrical properties,two-dimensional(2D)MoS_(2) cocatalysts have been widely applied in designing and developing highly efficient composite photocatalysts for hydrogen generation under suitable light irradiation.In this review,we first elaborated on the fundamental aspects of 2D MoS_(2) cocatalysts to include the structural design principles,synthesis strategies,strengths and challenges.Subsequently,we thoroughly highlighted and discussed the modification strategies of 2D MoS_(2) H2-evolution cocatalysts,including doping heteroatoms(e.g.metals,non-metals,and co-doping),designing interfacial coupling morphologies,controlling the physical properties(e.g.thickness,size,structural defects or pores),exposing the reactive facets or edge sites,constructing cocatalyst heterojunctions,engineering the interfacial bonds and confinement effects.In the future,the forefront challenges in understanding and in precise controlling of the active sites at molecular level or atomic level should be carefully studied,while various potential mechanisms of photogenerated-electrons interactions should be proposed.The applications of MoS_(2) cocatalyst in the overall water splitting are also expected.This review may offer new inspiration for designing and constructing novel and efficient MoS_(2)-based composite photocatalysts for highly efficient photocatalytic hydrogen evolution.
基金the National Science Foundation of China(Nos.22005228 and 52063028)。
文摘Photocatalytic Hproduction from water splitting has a promising prospect for alleviating energy and environmental issues.However,the fast recombination of photogenerated charge carriers limits the photocatalytic efficiency and its practical application.Cocatalyst engineering is an effective strategy to spatially separate photogenerated charge carriers.In this work,noble-metal-free MoSand CoOcocatalysts are loaded on CdS nanorods by a two-step photodeposition method.The MoSfunctions as the reduction cocatalyst to trap electrons and Co Oas the oxidation cocatalyst to trap holes.Transmission electron microscopy(TEM),inductively coupled plasma(ICP),X-ray photoelectron spectroscopy(XPS)and MottSchottky results demonstrate the effectiveness of photodeposition for loading MoSand CoOdual cocatalysts on CdS and their impact on the photochemical properties.The optimized CdS-MoS-CoOcomposite exhibits a high photocatalytic H-production rate of 7.4 mmol g^(-1)h^(-1)and an apparent quantum efficiency(QE)of 7.6%at 420 nm.Further analysis on time-resolved photoluminescence(TRPL)indicates that the introduction of dual cocatalysts greatly prolongs the lifetime of photogenerated charge carriers and deceases the charge recombination rates,consequently leading to superior photocatalytic H-production performance.This work provides a facile and effective strategy for the construction of highly efficient dual-cocatalyst-modified CdS photocatalyst for high-performance photocatalytic Hproduction.
基金supported by the National Natural Science Foundation of China(Grant No.22072022)the Natural Science Foundation of Fujian Province(2021L3003)the Science Foundation of Shandong Province(ZR2019BB065).
文摘Efficient photocatalytic reduction of CO_(2) to high-calorific-value CH4,an ideal target product,is a blueprint for C_(1)industry relevance and carbon neutrality,but it also faces great challenges.Herein,we demonstrate unprecedented hybrid SiC photocatalysts modified by Fe-based cocatalyst,which are prepared via a facile impregnation-reduction method,featuring an optimized local electronic structure.It exhibits a superior photocatalytic carbon-based products yield of 30.0μmol g^(−1) h^(−1) and achieves a record CH_(4) selectivity of up to 94.3%,which highlights the effectiveness of electron-rich Fe cocatalyst for boosting photocatalytic performance and selectivity.Specifically,the synergistic effects of directional migration of photogenerated electrons and strongπ-back bonding on low-valence Fe effectively strengthen the adsorption and activation of reactants and intermediates in the CO_(2)→CH_(4) pathway.This study inspires an effective strategy for enhancing the multielectron reduction capacity of semiconductor photocatalysts with low-cost Fe instead of noble metals as cocatalysts.
基金supported by the National Natural Science Foundation of China(Nos.51772197,51422206,51372159)the1000 Youth Talents Plan,the Key University Science Research Project of Jiangsu Province(17KJA430013)+1 种基金the 333 High-level Talents Cultivation Project of Jiangsu Province,Six Talents Peak Project of Jiangsu Province,Distinguished Young Scholars Foundation by Jiangsu Science and Technology Committee(BK20140009)Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘TiO2 photoanodes have aroused intensive research interest in photoelectrochemical (PEC) water splitting. However, they still suffer from poor electron-hole separation and sluggish oxygen evolution dynamics, leading to the low photoconversion efficiency and limiting commercial application. Here, we designed and fabricated novel ternary non-noble metal carbonate hydroxide (ZNC-CH) nanosheet cocatalysts and integrated them with TiO2 nanorod arrays as highly efficient photoanodes of PEC cells. Compared with the pristine TiO2, the photocurrent of photoanode with the optimal amount of ZNC-CH represents 3.2 times enhancement, and the onset potential is shifted toward the negative potential direction of 62 mV, The remarkable enhancement is attributed to the suppressed carrier recombination and enhanced charge transfer efficiency at the interface of TiO2, ZNC-CH and electrolyte, which is closely related to the zinc elements modulated intrinsic activity of catalysts. Our results demonstrate that the introduction of multimetallic ZNC-CH cocatalysts onto photoanodes is a promising strategy to improve the PEC efficiency.
基金Acknowledgements This work was financially supported in part by the National Natural Science Foundation of China (Nos. 21471141, U1532135, and 21603191), CAS Key Research Program of Frontier Sciences (No. QYZDB- SSW-SLH018), Zhejiang Provincial Natural Science Foundation (No. LQ16B010001), Recruitment Program of Global Experts, and CAS Hundred Talent Program XAFS measurements were performed at the beamline BL14W1 in the Shanghai Synchrotron Radiation Facility (SSRF), China.
文摘Photocatalytic reduction of CO2 into high value-added CH4 is a promising solution for energy and environmental crises. Integrating semiconductors with cocatalysts can improve the activities for photocatalytic CO2 reduction; however, most metal cocatalysts mainly produce CO and H2. Herein, we report a cocatalyst hydridation approach for significantly enhancing the photocatalytic reduction of CO2 into CH4. Hydriding Pd cocatalysts into PdH0.43 played a dual role in performance enhancement. As revealed by our isotopic labeling experiments, the PdH0.43 hydride cocatalysts reduced H2 evolution, which suppressed the H2 production and facilitated the conversion of the CO intermediate into the final product: CH4. Meanwhile, hydridation promoted the electron trapping on the cocatalysts, improving the charge separation. This approach increased the photocatalytic selectivity in CH4 production from 3.2% to 63.6% on Pd{100} and from 15.6% to 73.4% on Pd{111}. The results provide insights into photocatalytic mechanism studies and introduce new opportunities for designing materials towards photocatalytic CO2 conversion.
基金funding from the National Natural Science Foundation of China(No.51872173 and 51772176)Taishan Scholar Foundation of Shandong Province(No.tsqn201812068 and tspd20161006)+2 种基金Youth Innovation Technology Project of Higher School in Shandong Province(No.2019KJA013)Science and Technology Special Project of Qingdao City(No.20-3-4-3-nsh)the Opening Fund of State Key Laboratory of Heavy Oil Processing(No.SKLOP202002006)。
文摘2D-layered graphitic carbon nitride(g-C_(3)N_(4))is regarded as a great prospect as a photocatalyst for H_(2)generation.However,g-C_(3)N_(4)’s photocatalytic hydrogen evolution(HER)activity is significantly restricted by the recombination of photocarriers.We find that cobalt sulfide(CoS_(2))as a cocatalyst can promote g-C_(3)N_(4)nanosheets(NSs)to realize very efficient photocatalytic H_(2)generation.The prepared CoS_(2)/g-C_(3)N_(4)hybrids display highly boosted photocatalytic H_(2)generation performance and outstanding cycle stability.The optimized 7%-CoS_(2)/g-C_(3)N_(4)hybrids show a much improved photocatalytic H_(2)generation rate of 36.2μmol-1h-1,which is about 180 times as much as bare g-C_(3)N_(4)(0.2μmol-1h-1).In addition,the apparent quantum efficiency(AQE)of all the samples was computed under light atλ=370 nm,in which the AQE of 7%-CoS_(2)/g-C_(3)N_(4)hybrids is up to 5.72%.The experimental data and the DFT calculation suggest that the CoS_(2)/g-C_(3)N_(4)hybrid’s excellent HER activity is attributable to the lower overpotential and the smaller Co-H bond activation energy for HER.Accordingly,the CoS_(2)cocatalyst loading effectively boosts the photocatalytic performance of g-C_(3)N_(4)for H_(2)evolution.The project promotes fast development of high-efficiency photocatalysts and low-cost for photocatalytic H_(2)generation.
基金supported by the JSPS Leading Initiative for Excellent Young Researchers program(to Q.W.)the JST Fusion Oriented REsearch for disruptive Science and Technology program(to Q.W.)+1 种基金the JSPS Grant-in-Aid for Young Scientists(Start-up)(No.21K20485,to Q.W.No.20K22556,to Z.H.P.)。
文摘The global adoption of efficient sustainable energy sources is a crucial step toward meeting energy demands while achieving carbon emission reduction targets.Solar energy has become a clean and cost-competitive alternative to traditional fossil fuels,but the intermittent nature of sunlight results in challenges associated with energy storage and transport.Photocatalytic carbon dioxide reduction intends to mimic natural photosynthesis for utilizing sunlight to chemically convert water and CO_(2) into fuels.In this process,the solar energy is captured and stored in fuels,so-called solar fuels,for widespread on-demand use.Heterogeneous solar fuel production systems are multi-component,comprising light-harvesting(photosensitizer)and catalytic(cocatalyst)units.Cocatalysts are indispensable for photocatalytic CO_(2) reduction systems,which promote charge carrier separation and transport,reduce the reaction activation energy,and alter the reaction route,thereby enhancing the activity and selectivity of the photocatalytic reactions.This review presents a comprehensive summary of the recent advancements in cocatalysts for photocatalytic CO_(2) reduction reaction(CO_(2)RR),with the purpose of providing new insights and guidance to the field with regard to research directions and best practices.We summarize how various cocatalysts including inorganic nanoparticles,metal complexes,enzymes,and bacteria can be combined with semiconductor photosensitizer for light-driven photocatalytic CO_(2)RR.Side-by-side comparisons reveal the strengths and limitations of each kind of cocatalysts and how lessons extracted from studying natural photosynthetic systems can be applied to investigations of artificial photosynthesis,presenting an outlook discussing possible future concepts for a more effective photocatalytic CO_(2) reduction process.
基金supported by the Basic Science Center Program for Ordered Energy Conversion of the National Natural Science Foundation of China(No.51888103)the China National Key Research and Development Plan Project(No.2018YFB1502000)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2019JM-400).
文摘Photoelectrochemical(PEC)water splitting using semiconductors offers a promising way to convert renewable solar energy to clean hydrogen fuels.However,due to the sluggish reaction kinetics of water oxidation,significant charge recombination occurred at the photoanode/electrolyte interface and cause decrease of its PEC performance.To reduce the surface recombination,we deposit different transition metal complexes on BiVO4 nanocone arrays by a versatile light driven in-situ two electrode photodeposition approach without applied bias.Conformal cobalt phosphate“Co-Pi”,nickel borate“Ni-Bi”and manganese phosphate“Mn-Pi”complexes were deposited on BiVO4 nanocone arrays to form core-shell structure photoanode,all of which lead to enhanced photoelectrochemical performance.The photocurrent of the Co-Pi/BiVO4 photoanode under front-side illumination for 5 min is increased by 4 folds comparing to that of bare BiVO4 photoanode at 0.6 V vs.RHE,reaching a hole transfer efficiency as high as 94.5%at 1.23 V vs.RHE.The proposed photodeposition strategy is simple and efficient,and can be extended to deposite cocatalyst on other semiconductors with a valence band edge located at a potential more positive than the oxidation potential of transition metal ion in the cocatalyst.
基金financially supported by National Natural Science Foundation of China(22102002,52072001,51872003)Natural Science Foundation of Anhui Province(2108085QE192)。
文摘Spatially isolated oxidation and reduction cocatalysts on a semiconductor can realize efficient charge separation and thereby lead to increased photocatalytic hydrogen generation. However, the effective preparation of such photocatalysts has proven challenging.Herein, we report the facile synthesis of a novel noblemetal-free CdS/MoS/CoPi ternary photocatalyst via a visible light-induced synthesis route, in which MoSreduction cocatalysts were precisely grown on the two terminals of CdS nanorods, while CoPi oxidation cocatalysts were preferentially anchored onto the sidewalls of CdS nanorods. Such spatially isolated MoSand CoPi redox cocatalysts endow CdS nanorods with a rapid charge separation, which enhances their hydrogen generation activity. The CdS/MoS/CoPi photocatalyst with optimized CoPi amount achieves the highest Hgeneration rate of 206 μmol/h, which is 21 and 2 times higher than that achieved by using CdS alone(9.7 μmol/h) and CdS/MoS(105 μmol/h), respectively. The present work highlights the effectiveness of the spatial isolation of reduction and oxidation sites for efficient charge separation and thereby provides a promising strategy for the preparation of highly active photocatalysts.
基金the Strategic Emerging Industry Development Funds of Shenzhen(No.JCYJ20170817161720484).
文摘TiO_(2) has been considered as an ideal photocatalyst for water splitting.However,narrow light absorbance,low charge separation efficiency,and rare surface active sites lead to the low photocatalytic efficiency of TiO_(2).Although extensive research attempted to improve the situation,there is still lack of method for constructing high active and noble-metal-free TiO_(2) photocatalyst for H_(2) evolution reactions(HER).In this work,we loaded single atomic(SA)Ni(or Co)on the surface of anatase TiO_(2)(TiO_(2)(A))nanosheets by an isolation strategy.Ethylene diamine tetraacetic acid and ethylene glycol(EDTA-EG)compounds were used to chelate metal ions in solution and form carbon quantum dots in the following thermal treatment to isolate the metal ions on surface of TiO_(2)(A).The prepared Ni SA/TiO_(2)(A)catalyst owned a“skin wrapped body”structure with in-situ formed twodimensional(2D)heterojunction facilitating the fast electron transfer.As a result,the Ni SA/TiO_(2)(A)catalyst showed a high H_(2) evolution rate of 2,900μmol·g−1·h−1.This work provides an isolation strategy for constructing promising single-atom metal catalyst for photocatalysis and beyond.
基金supported by the National Key R&D Program of China(2021YFA1502100 and 2022YFE0114800)the National Natural Science Foundation of China(22372035,22302039 and 22311540011).
文摘Photocatalytic water splitting by semiconductors is a promising technology to produce clean H_(2) fuel,but the efficiency is restrained seriously by the high overpotential of the H_(2)-evolution reaction together with the high recombination rate of photoinduced charges.To enhance H_(2) production,it is highly desirable yet challenging to explore an efficient reductive cocatalyst and place it precisely on the right sites of the photocatalyst surface to work the proton reduction reaction exclusively.Herein,the metalloid NixP cocatalyst is exactly positioned on the Z-scheme Cd_(0.5)Zn_(0.5)S/NiTiO_(3)(CZS/NTO)heterostructure through a facile photodeposition strategy,which renders the cocatalyst form solely at the electron-collecting locations.It is revealed that the directional transfer of photoexcited electrons from Cd_(0.5)Zn_(0.5)S to Ni_(x)P suppresses the quenching of charge carriers.Under visible light,the CZS/NTO hybrid loaded with the Ni_(x)P cocatalyst exhibits an optimal H_(2) yield rate of 1103μmol h^(-1)(i.e.,27.57 mmol h^(-1)g^(-1)),which is about twofold of pristine CZS/NTO and comparable to the counterpart deposited with the Pt cocatalyst.Besides,the high apparent quantum yield(AQY)of 56%is reached at 400 nm.Further,the mechanisms of the cocatalyst formation and the H2 generation reaction are discussed in detail.
基金supported by United Arab Emirates University(UAEU),United Arab Emirates under research fund no 12N097。
文摘Photocatalytic solar to energy conversion is considered an attractive approach for overcoming energy crises and environmental concerns.Recently,titanium carbide(Ti_(3)C_(2))MXenes have been recognized as promising cocatalysts based on their metallic conductivity,excessive active reaction sites,and enlarged surface area.The current review focuses on the properties and applications of Ti_(3)C_(2)MXenes useful in the field of photocatalysis.More specifically,surface modification of Ti_(3)C_(2)MXenes by varying synthesis parameters to get pure materials and also composites with the role of functional groups towards solar energy conversion applications is highlighted in this review.The effect of etching and oxidizing pathways to get an efficient cocatalyst has been discussed in detail.Considering the significant effect of parameters,optimum synthesis conditions such as etchant type,concentration,time and type of intercalant in both the Ti_(3)C_(2)synthesis approaches for improved photoactivity are discussed.Additionally,the surface modification of Ti_(3)C_(2)through oxidation for TiO2growth on its surface is deliberated with a detailed discussion on etchant type,concentration,etching time,and environmental factors.The optimum oxidation condition,including temperature,time,and environment for thermal treatment of Ti_(3)C_(2),were also included.Lastly,the review summarizes the conclusion and future perspectives for solar energy conversion applications.
基金This work was supported by the Opening Project of the Key Laboratory of Green Chemistry of Sichuan Institutes of Higher Education(LZJ2002)the Open Project of Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province(CSPC2016-3-2).
文摘AgCl/Ti_(3)C_(2)@TiO_(2)ternary composites were prepared to form a heterojunction structure between AgCl and TiO_(2)and introduce Ti3C2 as a cocatalyst.The as-prepared AgCl/Ti_(3)C_(2)@TiO_(2)composites showed higher photocatalytic activity than pure AgCl and Ti_(3)C_(2)@TiO_(2)for photooxidation of a 1,4-dihydropyridine derivative(1,4-DHP)and tetracycline hydrochloride(TCH)under visible light irradiation(λ>400 nm).The photocatalytic activity of AgCl/Ti_(3)C_(2)@TiO_(2)composites depended on Ti_(3)C_(2)@TiO_(2)content,and the catalytic activity of the optimized samples were 6.9 times higher than that of pure AgCl for 1,4-DHP photodehydrogenation and 7.3 times higher than that of Ti_(3)C_(2)@TiO_(2)for TCH photooxidation.The increased photocatalytic activity was due to the formation of a heterojunction structure between AgCl and TiO_(2)and the introduction of Ti3C2 as a cocatalyst,which lowered the internal resistance,sped up the charge transfer,and increased the separation efficiency of photogenerated carries.Photogenerated holes and superoxide radical anions were the major active species in the photocatalytic process.
基金financially supported by the National Natural Science Foundation of China under Grants 21473183 and 21303079
文摘In the semiconductor-based photocatalysts for overall water splitting, loading proper cocatalysts play a crucial role in enhancing the photocatalytic activity. In this work, we have chosen Ni_n/α-Ga_2O_3 as a model and provided detailed density functional theory calculations to investigate the function of cocatalysts in hydrogen evolution reaction(HER). We have studied the formation and stability of Ni_n(n = 1–4) cluster on two stable surfaces of α-Ga_2O_3(001) and(012). In a Ni_n/α-Ga_2O_3 system, as the Ni 3d states well overlap with O and Ga states, the excited electrons transferred from Ga to Ni may participate in HER. We theoretically predict that introduction of Nincluster on(012) surface can elevate the Fermi level toward the conduction band, which is favorable for the occurrence of HER. Electrochemical computations are used to explore the mechanism of HER. It is found that, in most of Ni_n/α-Ga_2O_3 systems, the active sites of HER are on Ni_n clusters. Loading Ni_n clusters not only importantly reduces the Gibbs free energy of HER but also improves the reaction activity of surface O and Ga sites in HER. Our calculations reasonably explain the experimental observation on significant enhancement of activity for generating hydrogen after loading nickel oxide cocatalysts.
基金supported by the National Natural Science Foundation of China (21972048, 21802046)the Natural Science Foundation of Guangdong Province (Nos. 2019A1515011138, 2017A030313090, 2017A030310086, 2018A0303130018)。
文摘Cocatalysts play important roles in improving the activity and stability of most photocatalysts.It is of great significance to develop economical,efficient and stable cocatalysts.Herein,using Na2CoFe(CN)6 complex as precursor,a novel noble-metal-free FeCo@NGC cocatalyst(nano-FeCo alloy@N-doped graphitized carbon) is fabricated by a simple pyrolysis method.Coupling with g-C3 N4, the optimal FeCo@NGC/g-C3N4 receives a boosted visible light driven photocatalytic H2 evolution rate of 42.2 μmol h-1, which is even higher than that of 1.0 wt% Pt modified g-C3N4 photocatalyst.Based on the results of density functional theory(DFT) calculations and practical experiment measurements,such outstanding photocatalytic performance of FeCo@NGC/g-C3N4 is mainly attributed to two aspects.One is the accelerated charge transfer behavior,induced by a photogene rated electrons secondary transfer performance on the surface of FeCo alloy nanoparticles.The other is related to the adjustment of H adsorption energy(approaching the standard hydrogen electrode potential) by the presence of external NGC thin layer.Both factors play key roles in the H2 evolution reaction.Such outstanding performance highlights an enormous potential of developing noble-metal-free bimetallic nano-alloy as inexpensive and efficient cocatalysts for solar applications.