Photocatalytic splitting of water over p-type semiconductors is a promising strategy for production of hydrogen.However,the determination of rate law is rarely reported.To this purpose,copper oxide(CuO)is selected as ...Photocatalytic splitting of water over p-type semiconductors is a promising strategy for production of hydrogen.However,the determination of rate law is rarely reported.To this purpose,copper oxide(CuO)is selected as a model photocathode in this study,and the photogenerated surface charge density,interfacial charge transfer rate constant and their relation to the water reduction rate(in terms of photocurrent)were investigated by a combination of(photo)electrochemical techniques.The results showed that the charge transfer rate constant is exponential-dependent on the surface charge density,and that the photocurrent equals to the product of the charge transfer rate constant and surface charge density.The reaction is first-order in terms of surface charge density.Such an unconventional rate law contrasts with the reports in literature.The charge density-dependent rate constant results from the Fermi level pinning(i.e.,Galvani potential is the main driving force for the reaction)due to accumulation of charge in the surface states and/or Frumkin behavior(i.e.,chemical potential is the main driving force).This study,therefore,may be helpful for further investigation on the mechanism of hydrogen evolution over a CuO photocathode and for designing more efficient CuO-based photocatalysts.展开更多
Relationship between the activity for photocatalytic H_(2)O overall splitting(HOS)and the electron occupancy on d orbits of the active component in photocatalysts shows volcanic diagram,and specially the d^(10)electro...Relationship between the activity for photocatalytic H_(2)O overall splitting(HOS)and the electron occupancy on d orbits of the active component in photocatalysts shows volcanic diagram,and specially the d^(10)electronic configuration in valley bottom exhibits inert activity,which seriously fetters the development of catalytic materials with great potentials.Herein,In d^(10)electronic configuration of In_(2)O_(3)was activated by phosphorus atoms replacing its lattice oxygen to regulate the collocation of the ascended In 5p-band(Inɛ5p)and descended O 2p-band(Oɛ2p)centers as efficient active sites for chemisorption to*OH and*H during forward HOS,respectively,along with a declined In 4d-band center(Inɛ4d)to inhibit its backward reaction.A stable STH efficiency of 2.23%under AM 1.5 G irradiation at 65°C has been obtained over the activated d^(10)electronic configuration with a lowered activation energy for H_(2)evolution,verified by femtosecond transient absorption spectroscopy,in situ diffuse reflectance infrared Fourier transform spectroscopy and theoretical calculations of dynamics.These findings devote to activating d^(10)electronic configuration for resolving the reaction energy barrier and dynamical bottleneck of forward HOS,which expands the exploration of high-efficiency catalytic materials.展开更多
An immobilized Cu2O/g-C3N4 heterojunction film was successfully made on an FTO substrate by electrophoretic deposition of g-C3N4 on a Cu2O thin film.The photoelectrochemical(PEC) performance for water splitting by t...An immobilized Cu2O/g-C3N4 heterojunction film was successfully made on an FTO substrate by electrophoretic deposition of g-C3N4 on a Cu2O thin film.The photoelectrochemical(PEC) performance for water splitting by the Cu2O/g-C3N4 film was better than pure g-C3N4 and pure Cu2O film.Under-0.4 V external bias and visible light irradiation,the photocurrent density and PEC hydrogen evolution efficiency of the optimized Cu2O/g-C3N4 film was-1.38 mA/cm^2 and 0.48 mL h^-1 cm^-2,respectively.The enhanced PEC performance of Cu2O/g-C3N4 was attributed to the synergistic effect of light coupling and a matching energy band structure between g-C3N4 and Cu2O as well as the external bias.展开更多
A bismuth vanadate(BiVO4)photoanode with a cocatalyst consisting of NiFe layered double‐hydroxide(NiFe‐LDH)nanoparticles was fabricated for photoelectrochemical(PEC)water splitting.NiFe‐LDH nanoparticles,which can ...A bismuth vanadate(BiVO4)photoanode with a cocatalyst consisting of NiFe layered double‐hydroxide(NiFe‐LDH)nanoparticles was fabricated for photoelectrochemical(PEC)water splitting.NiFe‐LDH nanoparticles,which can improve light‐absorption capacities and facilitate efficient hole transfer to the surface,were deposited on the surface of the BiVO4 photoanode by a hydrothermal method.All the samples were characterized using X‐ray diffraction,scanning electron microscopy,and diffuse‐reflectance spectroscopy.Linear sweep voltammetry and current‐time plots were used to investigate the PEC activity.The photocurrent response of NiFe‐LDH/BiVO4 at 1.23 V vs the reversible hydrogen electrode was higher than those of Ni(OH)2/BiVO4,Fe(OH)2/BiVO4 and pure BiVO4 electrodes under visible‐light illumination.NiFe‐LDH/BiVO4 also gave a superior PEC hydrogen evolution performance.Furthermore,the stability of the NiFe‐LDH/BiVO4 photoanode was excellent compared with that of the bare BiVO4 photoanode,and offers a novel method for solar‐assisted water splitting.展开更多
Novel Bi2MoO6/TiO2 heterojunction was fabricated by growing Bi2MoO6 nanosheets arrays on the vertically aligned TiO2 nanorods arrays via a two-step solvothermal method. The obtained Bi2MoO6/TiO2 hierarchical heterojun...Novel Bi2MoO6/TiO2 heterojunction was fabricated by growing Bi2MoO6 nanosheets arrays on the vertically aligned TiO2 nanorods arrays via a two-step solvothermal method. The obtained Bi2MoO6/TiO2 hierarchical heterojunction showed excellent visible light photoelectrochemical performance. Compared with the pure TiO2 and Bi2MoO6, the photocurrent density of the heterojunction was increased 57 and 29 times, respectively. Furthermore, the hydrogen generation rate of the Bi2MoO6/TiO2 for photoelectrocatalytic water-splitting was about 6 times higher than that of the pure Bi2MoO6. The improved performance can be attributed to the synergistic effects of enhanced absorption of visible light, increase of migration rate and separation efficiency of photo-induced carriers.展开更多
As one of the most promising photoanode candidates for photoelectrochemical(PEC)water splitting,the photocurrent density of BiVO_(4) still needs to be further improved in order to meet the practical application.In thi...As one of the most promising photoanode candidates for photoelectrochemical(PEC)water splitting,the photocurrent density of BiVO_(4) still needs to be further improved in order to meet the practical application.In this work,a highly‐matched BiVO_(4)/WO_(3) nanobowl(NB)photoanode was constructed to enhance charge separation at the interface of the junction.Upon further modification of the BiVO_(4)/WO_(3)NB surface by NiOOH/FeOOH as an oxygen evolution cocatalyst(OEC)layer,a high photocurrent density of 3.05 mA cm^(−2) at 1.23 V vs.RHE has been achieved,which is about 5‐fold higher than pristine BiVO_(4) in neutral medium under AM 1.5 G illumination.5 times higher IPCE at 450 nm is also achieved compared with the BiVO_(4) photoanode,leading to about 95%faradaic efficiency for both H_(2) and O_(2) gas production.Systematic studies attribute the significantly enhanced PEC performance to the smaller BiVO_(4) particle size(<90 nm)than its hole diffusion length(~100 nm),the improved charge separation of BiVO_(4) by the single layer WO_(3) nanobowl array and the function of OEC layers.Such WO_(3)NB possesses much smaller interface resistance with the substrate FTO glass and larger contact area with BiVO_(4) nanoparticles.This approach provides new insights to design and fabricate BiVO_(4)‐based heterojunction photoanode for higher PEC water splitting performance.展开更多
Searching for low-cost widely applicable electrocatalysts for hydrogen production is very important. Here, 3D self-supported NiS2/MoS2 heterostructures were synthesized via a one-step millisecond- laser-direct-writing...Searching for low-cost widely applicable electrocatalysts for hydrogen production is very important. Here, 3D self-supported NiS2/MoS2 heterostructures were synthesized via a one-step millisecond- laser-direct-writing method;these structures exhibited excellent hydrogen evolution reaction activities over a wide pH range. The current density of 10 mA cm^-2 could be reached at low overpotentials of 98 and 159 mV in alkaline and neutral electrolytes, respectively. Such an outstanding electrocatalytic performance should be attributed to the integration of the 3D self-supported nanostructures, the high conductivity of the framework, and particularly, the incalculable heterointerfaces formed between NiS2 and MoS2. This work provides a new strategy to study interfacial engineering and the mechanism of interface enhancement.展开更多
Designing low-cost and high-performance photoelectrodes with improved light harvesting and charge separation rates is significant in photoelectrochemical water splitting.Here,a novel TiO2/Cu2O/Al/Al2O3 photoelectrode ...Designing low-cost and high-performance photoelectrodes with improved light harvesting and charge separation rates is significant in photoelectrochemical water splitting.Here,a novel TiO2/Cu2O/Al/Al2O3 photoelectrode is manufactured by depositing plasmonic nanoparticles of the non-noble metal Al on the surface of a TiO2/Cu2O core/shell heterojunction for the first time.The Al nanoparticles,which exhibit a surface plasmon resonance(SPR)effect and are substantially less expensive than noble metals such as Au and Ag,generate hot electron-hole pairs and amplify the electromagnetic field at the interface under illumination.The as-prepared TiO2/Cu2O/Al/Al2O3 photoelectrodes have an extended absorption range and enhanced carrier separation and transfer.Their photocurrent density of 4.52 mA·cm^-2 at 1.23 V vs.RHE represents an 1.84-fold improvement over that of TiO2/Cu2O.Specifically,the ultrathin Al2O3 passivation layer spontaneously generated on the surface of Al in air could act as a protective layer to significantly increase its stability.In this work,the synergistic effect of the heterojunctions and the SPR effect of the non-noble metal Al significantly improve the photoelectrode performance,providing a novel concept for the design of electrodes with good properties and high practicability.展开更多
Depositing a cocatalyst has proven to be an important strategy for improving the photoelectrochemical(PEC)water-splitting efficiency of photoanodes.In this study,Ni(OH)2 quantum dots(Ni(OH)2 QDs)were deposited in situ...Depositing a cocatalyst has proven to be an important strategy for improving the photoelectrochemical(PEC)water-splitting efficiency of photoanodes.In this study,Ni(OH)2 quantum dots(Ni(OH)2 QDs)were deposited in situ onto anα-Fe_(2)O_(3)photoanode via a chelation-mediated hydrolysis method.The photocurrent density of the Ni(OH)2 QDs/α-Fe_(2)O_(3)photoanode reached 1.93 mA·cm^(−2)at 1.23 V vs.RHE,which is 3.5 times that ofα-Fe_(2)O_(3),and an onset potential with a negative shift of ca.100 mV was achieved.More importantly,the Ni(OH)2 QDs exhibited excellent stability in maintaining PEC water oxidation at a high current density,which is attributed to the ultra-small crystalline size,allowing for the rapid acceptance of holes fromα-Fe_(2)O_(3)to Ni(OH)_(2)QDs,formation of active sites for water oxidation,and hole transfer from the active sites to water molecules.Further(photo)electrochemical analysis suggests that Ni(OH)_(2)QDs not only provide maximal active sites for water oxidation but also suppress charge recombination by passivating the surface states ofα-Fe_(2)O_(3),thereby significantly enhancing the water oxidation kinetics over theα-Fe_(2)O_(3)surface.展开更多
Hydrogen production via solar water splitting is regarded as one of the most promising ways to utilize solar energy and has attracted more and more attention. Great progress has been made on photocatalytic water split...Hydrogen production via solar water splitting is regarded as one of the most promising ways to utilize solar energy and has attracted more and more attention. Great progress has been made on photocatalytic water splitting for hydrogen production in the past few years. This review summarizesthe very recent progress (mainly in the last 2–3 years) on three major types of solar hydrogenproduction systems: particulate photocatalysis (PC) systems, photoelectrochemical (PEC) systems,and photovoltaic‐photoelectrochemical (PV‐PEC) hybrid systems. The solar‐to‐hydrogen (STH)conversion efficiency of PC systems has recently exceeded 1.0% using a SrTiO3:La,Rh/Au/BiVO4:Mophotocatalyst, 2.5% for PEC water splitting on a tantalum nitride photoanode, and reached 22.4%for PV‐PEC water splitting using a multi‐junction GaInP/GaAs/Ge cell and Ni electrode hybrid system.The advantages and disadvantages of these systems for hydrogen production via solar watersplitting, especially for their potential demonstration and application in the future, are briefly describedand discussed. Finally, the challenges and opportunities for solar water splitting solutions are also forecasted.展开更多
Photoactive WO3is attractive as a photocatalyst for green energy evolution through water splitting.In the present work,an electrochemical anodic oxidation method was used to fabricate a photo‐responsive nanotube arra...Photoactive WO3is attractive as a photocatalyst for green energy evolution through water splitting.In the present work,an electrochemical anodic oxidation method was used to fabricate a photo‐responsive nanotube array‐like WO3/W(NA‐WO3/W)photoanode from W foil as a precursor.Compared with a reference commercial WO3/W electrode,the NA‐WO3/W photoanode exhibited enhanced and stable photoelectrocatalytic(PEC)activity for visible‐light‐driven water splitting with a typical H2/O2stoichiometric ratio of2:1and quantum efficiency of approximately5.23%under visible‐light irradiation from a light‐emitting diode(λ=420nm,15mW/cm2).The greatly enhanced PEC performance of the NA‐WO3/Wphotoanode was attributed to its fast electron–hole separation rate,which resulted from the one‐dimensional nanotube array‐like structure,high crystallinity of monoclinic WO3,and strong interaction between WO3and W foil.This work paves the way to a facile route to prepare highly active photoelectrodes for solar light transfer to chemical energy.展开更多
Developing highly active catalysts for photo/electrocatalytic water splitting is an attractive strategy to produce H2 as a renewable energy source.In this study,a new nickel boron oxide/graphdiyne(NiBi/GDY)hybrid cata...Developing highly active catalysts for photo/electrocatalytic water splitting is an attractive strategy to produce H2 as a renewable energy source.In this study,a new nickel boron oxide/graphdiyne(NiBi/GDY)hybrid catalyst was prepared by a facile synthetic approach.Benefitting from the strong electron donating ability of graphdiyne,NiBi/GDY showed an optimized electronic structure containing lower valence nickel atoms and demonstrated improved catalytic performance.As expected,NiBi/GDY displayed a high photocatalytic H2 evolution rate of 4.54 mmol g^(-1)h^(-1),2.9 and 4.5 times higher than those of NiBi/graphene and NiBi,respectively.NiBi/GDY also displayed outstanding electrocatalytic H2 evolution activity in 1.0 M KOH solution,with a current density of 400 mA/cm^(2)at an overpotential of 478.0 mV,which is lower than that of commercial Pt/C(505.3 mV@400 mA/cm^(2)).This work demonstrates that GDY is an ideal support for the development of highly active catalysts for photo/electrocatalytic H2 evolution.展开更多
Photocatalytic hydrogen(H2)evolution via water spilling over semiconductors has been considered to be one of the most promising strategies for sustainable energy supply in the future to provide non-pollution and renew...Photocatalytic hydrogen(H2)evolution via water spilling over semiconductors has been considered to be one of the most promising strategies for sustainable energy supply in the future to provide non-pollution and renewable energy.The key to efficient conversion of solar-chemical energy is the design of an efficient structure for high charge separation and transportation.Therefore,cocatalysts are necessary in boosting photocatalytic H2 evolution.To date,semiconductor photocatalysts have been modified by various cocatalysts due to the extended light harvest,enhanced charge carrier separation efficiency and improved stability.This review focuses on recent developments of cocatalysts in photocatalytic H2 evolution,the roles and mechanism of the cocatalysts are discussed in detail.The cocatalysts can be divided into the following categories:metal/alloy cocatalysts,metal phosphides cocatalysts,metal oxide/hydroxide cocatalysts,carbon-based cocatalysts,dual cocatalysts,Z-scheme cocatalysts and MOFs cocatalysts.The future research and forecast for photocatalytic hydrogen generation are also suggested.展开更多
Solar-driven water splitting is considered as a promising method to mitigate the energy crisis and various environmental issues.Bismuth vanadate(BiVO_(4))is photoanode material with tremendous potential for photoelect...Solar-driven water splitting is considered as a promising method to mitigate the energy crisis and various environmental issues.Bismuth vanadate(BiVO_(4))is photoanode material with tremendous potential for photoelectrochemical(PEC)water splitting.However,its PEC performance is severely hindered owing to poor surface charge transfer,surface recombination at the photoanode/electrolyte junction,and sluggish oxygen evolution reaction(OER)kinetics.In this regard,a novel solution was developed in this study to address these issues by decorating the surface of BiVO_(4)with cobalt sulfide,whose attractive features such as low cost,high conductivity,and rapid charge-transfer ability assisted in improving the PEC activity of the BiVO_(4)photoanode.The fabricated photoanode exhibited a significantly enhanced photocurrent density of 3.2 m A cm^(-2)under illumination at 1.23 V vs.a reversible hydrogen electrode,which is more than 2.5 times greater than that of pristine BiVO_(4).Moreover,the Co S/BiVO_(4)photoanode also exhibited considerable improvements in the charge injection yield(75.8%vs.36.7%for the bare BiVO_(4)film)and charge separation efficiency(79.8%vs.66.8%for the pristine BiVO_(4)film).These dramatic enhancements were primarily ascribed to rapid charge-transport kinetics and efficient reduction of the anodic overpotential for oxygen evolution enabled by the surface modification of BiVO_(4)by Co S.This study provides valuable suggestions for designing efficient photocatalysts via surface modification to improve the PEC performance.展开更多
In recent years,ternary heterostructures(HSs)composed of three semiconductors have attracted significant attention because of the effective separation and transfer of photogenerated electrons and holes in these materi...In recent years,ternary heterostructures(HSs)composed of three semiconductors have attracted significant attention because of the effective separation and transfer of photogenerated electrons and holes in these materials.In this work,new ternary Cd S/Zn S/Zn O(CZZ)HSs with one-dimensional(1D)nanofiber morphology have been successfully fabricated for the first time by a series of processes:electrospinning Zn O nanofibers,sulfurizing Zn O in situ to form Zn S/Zn O binary HSs,and depositing Cd S quantum dots in situ on the Zn S/Zn O HSs.Benefiting from the efficient separation and transfer of photoinduced charge carriers,the optimized CZZ ternary HSs exhibit a hydrogen evolution rate of 51.45 mmol h^-1 g^-1(quantum efficiency:26.88%at 420 nm)without any co-catalyst,which is 93.54 and 2.28 times higher than those exhibited by pristine Zn O and Zn S/Zn O binary HSs,respectively,under the same conditions.Furthermore,the rate of hydrogen evolution over the 1D CZZ nanofibers is significantly higher than that over 2D CZZ nanosheets(27.25 mmol h^-1 g^-1,in the presence of a Pt co-catalyst)prepared by the same sulfurization and deposition procedures.This can be ascribed to the significantly smaller geometric sizes of 1D nanofibers compared to those of 2D nanosheets,resulting in effectively suppressed recombination of photogenerated charge carriers and promotion of photocatalytic H2 evolution performance.展开更多
We report on a novel g-C3N4/TiO 2/Co-Pi photoanode combining a TiO2 protection layer, Co-Pi hole capture layer, and g-C3 N4 light-absorption layer layer for photoelectrochemical(PEC) water splitting to generate hydr...We report on a novel g-C3N4/TiO 2/Co-Pi photoanode combining a TiO2 protection layer, Co-Pi hole capture layer, and g-C3 N4 light-absorption layer layer for photoelectrochemical(PEC) water splitting to generate hydrogen for the first time. This new photoanode with three function layers exhibits enhanced PEC performance with a photocurrent density of 0.346 mA ·cm–2 at 1.1 V(vs. RHE),which is approximately 3.6 times that of pure g-C3N4 photoanode. The enhanced PEC performance of g-C3N4/TiO 2/Co-Pi photoanode benefits from the following:(1) excellent visible light absorption of g-C3N4;(2) stable protection of TiO2 to improve the durability of g-C3N4 film; and(3) photogenerated holes capture Co-Pi to separate photogenerated electron-hole pairs efficiently. This promising multifarious function layers structure provides a new perspective for PEC water splitting to generate hydrogen.展开更多
基金the National Basic Research Development of China(2011CB936003)the National Natural Science Foundation of China(50971116)。
文摘Photocatalytic splitting of water over p-type semiconductors is a promising strategy for production of hydrogen.However,the determination of rate law is rarely reported.To this purpose,copper oxide(CuO)is selected as a model photocathode in this study,and the photogenerated surface charge density,interfacial charge transfer rate constant and their relation to the water reduction rate(in terms of photocurrent)were investigated by a combination of(photo)electrochemical techniques.The results showed that the charge transfer rate constant is exponential-dependent on the surface charge density,and that the photocurrent equals to the product of the charge transfer rate constant and surface charge density.The reaction is first-order in terms of surface charge density.Such an unconventional rate law contrasts with the reports in literature.The charge density-dependent rate constant results from the Fermi level pinning(i.e.,Galvani potential is the main driving force for the reaction)due to accumulation of charge in the surface states and/or Frumkin behavior(i.e.,chemical potential is the main driving force).This study,therefore,may be helpful for further investigation on the mechanism of hydrogen evolution over a CuO photocathode and for designing more efficient CuO-based photocatalysts.
文摘Relationship between the activity for photocatalytic H_(2)O overall splitting(HOS)and the electron occupancy on d orbits of the active component in photocatalysts shows volcanic diagram,and specially the d^(10)electronic configuration in valley bottom exhibits inert activity,which seriously fetters the development of catalytic materials with great potentials.Herein,In d^(10)electronic configuration of In_(2)O_(3)was activated by phosphorus atoms replacing its lattice oxygen to regulate the collocation of the ascended In 5p-band(Inɛ5p)and descended O 2p-band(Oɛ2p)centers as efficient active sites for chemisorption to*OH and*H during forward HOS,respectively,along with a declined In 4d-band center(Inɛ4d)to inhibit its backward reaction.A stable STH efficiency of 2.23%under AM 1.5 G irradiation at 65°C has been obtained over the activated d^(10)electronic configuration with a lowered activation energy for H_(2)evolution,verified by femtosecond transient absorption spectroscopy,in situ diffuse reflectance infrared Fourier transform spectroscopy and theoretical calculations of dynamics.These findings devote to activating d^(10)electronic configuration for resolving the reaction energy barrier and dynamical bottleneck of forward HOS,which expands the exploration of high-efficiency catalytic materials.
基金supported by the National Natural Science Foundation of China (21173088)the Science and Technology Project of Guangdong Province (2014A030312007, 2015A050502012, 2016A010104013)+1 种基金the China Postdoctoral Science Foundation (2016M592493)the Open Research Fund of Hunan Key Laboratory of Applied Environmental Photocatalysis (CCSU-XT-06),Changsha University~~
文摘An immobilized Cu2O/g-C3N4 heterojunction film was successfully made on an FTO substrate by electrophoretic deposition of g-C3N4 on a Cu2O thin film.The photoelectrochemical(PEC) performance for water splitting by the Cu2O/g-C3N4 film was better than pure g-C3N4 and pure Cu2O film.Under-0.4 V external bias and visible light irradiation,the photocurrent density and PEC hydrogen evolution efficiency of the optimized Cu2O/g-C3N4 film was-1.38 mA/cm^2 and 0.48 mL h^-1 cm^-2,respectively.The enhanced PEC performance of Cu2O/g-C3N4 was attributed to the synergistic effect of light coupling and a matching energy band structure between g-C3N4 and Cu2O as well as the external bias.
基金supported by the National Natural Science Foundation of China(21663027,51262028,21261021)the Science and Technology Support Project of Gansu Province(1504GKCA027)+2 种基金the Program for the Young Innovative Talents of Longyuanthe Program for Innovative Research Team(NWNULKQN-15-2)the Undergraduate Academic Innovative Research Team of Northwest Normal University~~
文摘A bismuth vanadate(BiVO4)photoanode with a cocatalyst consisting of NiFe layered double‐hydroxide(NiFe‐LDH)nanoparticles was fabricated for photoelectrochemical(PEC)water splitting.NiFe‐LDH nanoparticles,which can improve light‐absorption capacities and facilitate efficient hole transfer to the surface,were deposited on the surface of the BiVO4 photoanode by a hydrothermal method.All the samples were characterized using X‐ray diffraction,scanning electron microscopy,and diffuse‐reflectance spectroscopy.Linear sweep voltammetry and current‐time plots were used to investigate the PEC activity.The photocurrent response of NiFe‐LDH/BiVO4 at 1.23 V vs the reversible hydrogen electrode was higher than those of Ni(OH)2/BiVO4,Fe(OH)2/BiVO4 and pure BiVO4 electrodes under visible‐light illumination.NiFe‐LDH/BiVO4 also gave a superior PEC hydrogen evolution performance.Furthermore,the stability of the NiFe‐LDH/BiVO4 photoanode was excellent compared with that of the bare BiVO4 photoanode,and offers a novel method for solar‐assisted water splitting.
基金This work was supported by the National Natural Science Foundation of China (No.U1632273).
文摘Novel Bi2MoO6/TiO2 heterojunction was fabricated by growing Bi2MoO6 nanosheets arrays on the vertically aligned TiO2 nanorods arrays via a two-step solvothermal method. The obtained Bi2MoO6/TiO2 hierarchical heterojunction showed excellent visible light photoelectrochemical performance. Compared with the pure TiO2 and Bi2MoO6, the photocurrent density of the heterojunction was increased 57 and 29 times, respectively. Furthermore, the hydrogen generation rate of the Bi2MoO6/TiO2 for photoelectrocatalytic water-splitting was about 6 times higher than that of the pure Bi2MoO6. The improved performance can be attributed to the synergistic effects of enhanced absorption of visible light, increase of migration rate and separation efficiency of photo-induced carriers.
文摘As one of the most promising photoanode candidates for photoelectrochemical(PEC)water splitting,the photocurrent density of BiVO_(4) still needs to be further improved in order to meet the practical application.In this work,a highly‐matched BiVO_(4)/WO_(3) nanobowl(NB)photoanode was constructed to enhance charge separation at the interface of the junction.Upon further modification of the BiVO_(4)/WO_(3)NB surface by NiOOH/FeOOH as an oxygen evolution cocatalyst(OEC)layer,a high photocurrent density of 3.05 mA cm^(−2) at 1.23 V vs.RHE has been achieved,which is about 5‐fold higher than pristine BiVO_(4) in neutral medium under AM 1.5 G illumination.5 times higher IPCE at 450 nm is also achieved compared with the BiVO_(4) photoanode,leading to about 95%faradaic efficiency for both H_(2) and O_(2) gas production.Systematic studies attribute the significantly enhanced PEC performance to the smaller BiVO_(4) particle size(<90 nm)than its hole diffusion length(~100 nm),the improved charge separation of BiVO_(4) by the single layer WO_(3) nanobowl array and the function of OEC layers.Such WO_(3)NB possesses much smaller interface resistance with the substrate FTO glass and larger contact area with BiVO_(4) nanoparticles.This approach provides new insights to design and fabricate BiVO_(4)‐based heterojunction photoanode for higher PEC water splitting performance.
基金financially supported by the National Natural Science Foundation of China(51572188 and 51822106)~~
文摘Searching for low-cost widely applicable electrocatalysts for hydrogen production is very important. Here, 3D self-supported NiS2/MoS2 heterostructures were synthesized via a one-step millisecond- laser-direct-writing method;these structures exhibited excellent hydrogen evolution reaction activities over a wide pH range. The current density of 10 mA cm^-2 could be reached at low overpotentials of 98 and 159 mV in alkaline and neutral electrolytes, respectively. Such an outstanding electrocatalytic performance should be attributed to the integration of the 3D self-supported nanostructures, the high conductivity of the framework, and particularly, the incalculable heterointerfaces formed between NiS2 and MoS2. This work provides a new strategy to study interfacial engineering and the mechanism of interface enhancement.
文摘Designing low-cost and high-performance photoelectrodes with improved light harvesting and charge separation rates is significant in photoelectrochemical water splitting.Here,a novel TiO2/Cu2O/Al/Al2O3 photoelectrode is manufactured by depositing plasmonic nanoparticles of the non-noble metal Al on the surface of a TiO2/Cu2O core/shell heterojunction for the first time.The Al nanoparticles,which exhibit a surface plasmon resonance(SPR)effect and are substantially less expensive than noble metals such as Au and Ag,generate hot electron-hole pairs and amplify the electromagnetic field at the interface under illumination.The as-prepared TiO2/Cu2O/Al/Al2O3 photoelectrodes have an extended absorption range and enhanced carrier separation and transfer.Their photocurrent density of 4.52 mA·cm^-2 at 1.23 V vs.RHE represents an 1.84-fold improvement over that of TiO2/Cu2O.Specifically,the ultrathin Al2O3 passivation layer spontaneously generated on the surface of Al in air could act as a protective layer to significantly increase its stability.In this work,the synergistic effect of the heterojunctions and the SPR effect of the non-noble metal Al significantly improve the photoelectrode performance,providing a novel concept for the design of electrodes with good properties and high practicability.
文摘Depositing a cocatalyst has proven to be an important strategy for improving the photoelectrochemical(PEC)water-splitting efficiency of photoanodes.In this study,Ni(OH)2 quantum dots(Ni(OH)2 QDs)were deposited in situ onto anα-Fe_(2)O_(3)photoanode via a chelation-mediated hydrolysis method.The photocurrent density of the Ni(OH)2 QDs/α-Fe_(2)O_(3)photoanode reached 1.93 mA·cm^(−2)at 1.23 V vs.RHE,which is 3.5 times that ofα-Fe_(2)O_(3),and an onset potential with a negative shift of ca.100 mV was achieved.More importantly,the Ni(OH)2 QDs exhibited excellent stability in maintaining PEC water oxidation at a high current density,which is attributed to the ultra-small crystalline size,allowing for the rapid acceptance of holes fromα-Fe_(2)O_(3)to Ni(OH)_(2)QDs,formation of active sites for water oxidation,and hole transfer from the active sites to water molecules.Further(photo)electrochemical analysis suggests that Ni(OH)_(2)QDs not only provide maximal active sites for water oxidation but also suppress charge recombination by passivating the surface states ofα-Fe_(2)O_(3),thereby significantly enhancing the water oxidation kinetics over theα-Fe_(2)O_(3)surface.
基金supported by the National Basic Research Program of the Ministry of Science and Technology (973 Program, 2014CB239400)the National Natural Science Foundation of China (21501236, 21673230)Youth Innovation Promotion Association of Chinese Academy of Sciences (2016167)~~
文摘Hydrogen production via solar water splitting is regarded as one of the most promising ways to utilize solar energy and has attracted more and more attention. Great progress has been made on photocatalytic water splitting for hydrogen production in the past few years. This review summarizesthe very recent progress (mainly in the last 2–3 years) on three major types of solar hydrogenproduction systems: particulate photocatalysis (PC) systems, photoelectrochemical (PEC) systems,and photovoltaic‐photoelectrochemical (PV‐PEC) hybrid systems. The solar‐to‐hydrogen (STH)conversion efficiency of PC systems has recently exceeded 1.0% using a SrTiO3:La,Rh/Au/BiVO4:Mophotocatalyst, 2.5% for PEC water splitting on a tantalum nitride photoanode, and reached 22.4%for PV‐PEC water splitting using a multi‐junction GaInP/GaAs/Ge cell and Ni electrode hybrid system.The advantages and disadvantages of these systems for hydrogen production via solar watersplitting, especially for their potential demonstration and application in the future, are briefly describedand discussed. Finally, the challenges and opportunities for solar water splitting solutions are also forecasted.
基金supported by the National Natural Science Foundation of China(21207090,21477079,21261140333)PCSIRT(IRT1269)a scheme administrated by Shanghai Normal University(DXL122,and S30406)~~
文摘Photoactive WO3is attractive as a photocatalyst for green energy evolution through water splitting.In the present work,an electrochemical anodic oxidation method was used to fabricate a photo‐responsive nanotube array‐like WO3/W(NA‐WO3/W)photoanode from W foil as a precursor.Compared with a reference commercial WO3/W electrode,the NA‐WO3/W photoanode exhibited enhanced and stable photoelectrocatalytic(PEC)activity for visible‐light‐driven water splitting with a typical H2/O2stoichiometric ratio of2:1and quantum efficiency of approximately5.23%under visible‐light irradiation from a light‐emitting diode(λ=420nm,15mW/cm2).The greatly enhanced PEC performance of the NA‐WO3/Wphotoanode was attributed to its fast electron–hole separation rate,which resulted from the one‐dimensional nanotube array‐like structure,high crystallinity of monoclinic WO3,and strong interaction between WO3and W foil.This work paves the way to a facile route to prepare highly active photoelectrodes for solar light transfer to chemical energy.
文摘Developing highly active catalysts for photo/electrocatalytic water splitting is an attractive strategy to produce H2 as a renewable energy source.In this study,a new nickel boron oxide/graphdiyne(NiBi/GDY)hybrid catalyst was prepared by a facile synthetic approach.Benefitting from the strong electron donating ability of graphdiyne,NiBi/GDY showed an optimized electronic structure containing lower valence nickel atoms and demonstrated improved catalytic performance.As expected,NiBi/GDY displayed a high photocatalytic H2 evolution rate of 4.54 mmol g^(-1)h^(-1),2.9 and 4.5 times higher than those of NiBi/graphene and NiBi,respectively.NiBi/GDY also displayed outstanding electrocatalytic H2 evolution activity in 1.0 M KOH solution,with a current density of 400 mA/cm^(2)at an overpotential of 478.0 mV,which is lower than that of commercial Pt/C(505.3 mV@400 mA/cm^(2)).This work demonstrates that GDY is an ideal support for the development of highly active catalysts for photo/electrocatalytic H2 evolution.
基金financially supported by the National Natural Science Foundation of China(51572295,21273285 and 21003157)Beijing Nova Program(2008B76)Science Foundation of China University of Petroleum,Beijing(KYJJ2012-06-20 and 2462016YXBS05)~~
文摘Photocatalytic hydrogen(H2)evolution via water spilling over semiconductors has been considered to be one of the most promising strategies for sustainable energy supply in the future to provide non-pollution and renewable energy.The key to efficient conversion of solar-chemical energy is the design of an efficient structure for high charge separation and transportation.Therefore,cocatalysts are necessary in boosting photocatalytic H2 evolution.To date,semiconductor photocatalysts have been modified by various cocatalysts due to the extended light harvest,enhanced charge carrier separation efficiency and improved stability.This review focuses on recent developments of cocatalysts in photocatalytic H2 evolution,the roles and mechanism of the cocatalysts are discussed in detail.The cocatalysts can be divided into the following categories:metal/alloy cocatalysts,metal phosphides cocatalysts,metal oxide/hydroxide cocatalysts,carbon-based cocatalysts,dual cocatalysts,Z-scheme cocatalysts and MOFs cocatalysts.The future research and forecast for photocatalytic hydrogen generation are also suggested.
文摘Solar-driven water splitting is considered as a promising method to mitigate the energy crisis and various environmental issues.Bismuth vanadate(BiVO_(4))is photoanode material with tremendous potential for photoelectrochemical(PEC)water splitting.However,its PEC performance is severely hindered owing to poor surface charge transfer,surface recombination at the photoanode/electrolyte junction,and sluggish oxygen evolution reaction(OER)kinetics.In this regard,a novel solution was developed in this study to address these issues by decorating the surface of BiVO_(4)with cobalt sulfide,whose attractive features such as low cost,high conductivity,and rapid charge-transfer ability assisted in improving the PEC activity of the BiVO_(4)photoanode.The fabricated photoanode exhibited a significantly enhanced photocurrent density of 3.2 m A cm^(-2)under illumination at 1.23 V vs.a reversible hydrogen electrode,which is more than 2.5 times greater than that of pristine BiVO_(4).Moreover,the Co S/BiVO_(4)photoanode also exhibited considerable improvements in the charge injection yield(75.8%vs.36.7%for the bare BiVO_(4)film)and charge separation efficiency(79.8%vs.66.8%for the pristine BiVO_(4)film).These dramatic enhancements were primarily ascribed to rapid charge-transport kinetics and efficient reduction of the anodic overpotential for oxygen evolution enabled by the surface modification of BiVO_(4)by Co S.This study provides valuable suggestions for designing efficient photocatalysts via surface modification to improve the PEC performance.
文摘In recent years,ternary heterostructures(HSs)composed of three semiconductors have attracted significant attention because of the effective separation and transfer of photogenerated electrons and holes in these materials.In this work,new ternary Cd S/Zn S/Zn O(CZZ)HSs with one-dimensional(1D)nanofiber morphology have been successfully fabricated for the first time by a series of processes:electrospinning Zn O nanofibers,sulfurizing Zn O in situ to form Zn S/Zn O binary HSs,and depositing Cd S quantum dots in situ on the Zn S/Zn O HSs.Benefiting from the efficient separation and transfer of photoinduced charge carriers,the optimized CZZ ternary HSs exhibit a hydrogen evolution rate of 51.45 mmol h^-1 g^-1(quantum efficiency:26.88%at 420 nm)without any co-catalyst,which is 93.54 and 2.28 times higher than those exhibited by pristine Zn O and Zn S/Zn O binary HSs,respectively,under the same conditions.Furthermore,the rate of hydrogen evolution over the 1D CZZ nanofibers is significantly higher than that over 2D CZZ nanosheets(27.25 mmol h^-1 g^-1,in the presence of a Pt co-catalyst)prepared by the same sulfurization and deposition procedures.This can be ascribed to the significantly smaller geometric sizes of 1D nanofibers compared to those of 2D nanosheets,resulting in effectively suppressed recombination of photogenerated charge carriers and promotion of photocatalytic H2 evolution performance.
基金supported by the Science Funds of Tianjin for Distinguished Young Scholar(17JCJQJC44800)Natural Science Foundation of Tianjin(16JCYBJC17900)Open Foundation of Hubei Collaborative Innovation Center for High-efficient Utilization of Solar Energy(HBSKFZD2017001)~~
文摘We report on a novel g-C3N4/TiO 2/Co-Pi photoanode combining a TiO2 protection layer, Co-Pi hole capture layer, and g-C3 N4 light-absorption layer layer for photoelectrochemical(PEC) water splitting to generate hydrogen for the first time. This new photoanode with three function layers exhibits enhanced PEC performance with a photocurrent density of 0.346 mA ·cm–2 at 1.1 V(vs. RHE),which is approximately 3.6 times that of pure g-C3N4 photoanode. The enhanced PEC performance of g-C3N4/TiO 2/Co-Pi photoanode benefits from the following:(1) excellent visible light absorption of g-C3N4;(2) stable protection of TiO2 to improve the durability of g-C3N4 film; and(3) photogenerated holes capture Co-Pi to separate photogenerated electron-hole pairs efficiently. This promising multifarious function layers structure provides a new perspective for PEC water splitting to generate hydrogen.