Highly selective photocatalytic reduction of CO_(2) to CH_(4) on electron-rich Fe species cocatalyst under visible light irradiation

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.

Room-temperature solid phase surface engineering of BiOI sheets stacking g-C_(3)N_(4) boosts photocatalytic reduction of Cr(Ⅵ)

Cr(Ⅵ)-based compounds pollution have attracted global concern due to serious harm to humans and environment.Hence,it is crucial to exploit an effective technique to eliminate Cr(Ⅵ)in water.Herein,we in-situ grown BiOI on graphitic carbon nitride to prepare the BiOI/g-C_(3)N_(4)(BCN)direct Z-scheme heterojunction by solid phase engineering method at room temperature.Experimental result shown the photocatalytic activity of pure BiOI were obviously enhanced by constructing Z-scheme BCN heterostructure,and BCN-3 heterostructure exhibited the optimal photocatalytic degradation of RhB with 98%yield for 2.5 h and reduction of Cr(Ⅵ)with more than 99%yield for 1.5 h at pH=2.Stability test shows BCN-3 still kept more than 98%reduction efficiency after 6 cycles.In addition,we also studied the reduction mechanism that shown the.O_(2)^(-)radicals essentially helped to reduce the Cr(Ⅵ)in aqueous solution under illumination,verified the direct Z-scheme charge transfer path by X-ray photoelectron spectroscopy(XPS)and the free radical trapping experiment.The work open a new way for rationally designing photocatalyst heterostructure to reduce Cr(Ⅵ)to Cr(Ⅲ).

One-step synthesis of defected Bi_(2)Al_(4)O_(9)/β-Bi_(2)O_(3) heterojunctions for photocatalytic reduction of CO_(2) to CO

Defect and charge transfer efficiency of nano-photocatalysts are important factors which influence their photocatalytic performance.In this work,oxygen vacancies are successfully introduced in the synthesis process of Bi_(2)Al_(4)O_(9)/β-Bi_(2)O_(3)heterojunctions through one-step in situ selfcombustion method.High-resolution transmission electron microscopy (HRTEM),UV-Vis diffuse reflectance spectra (UV-Vis DRS),and electron spin resonance (ESR) measurements confirm the existence of oxygen vacancies.In addition,by controlling the ratio of reactants of Bi(NO_(3))_(3)to Al(NO_(3))_(3),the ratio of Bi_(2)Al_(4)O_(9)and β-Bi_(2)O_(3)in the heterojunction can be easily adjusted.Photocurrent responses and surface photovoltage spectroscopy (SPV) indicate that the construction of the Bi_(2)Al_(4)O_(9)/β-Bi_(2)O_(3)heterostructure improves the separation efficiency of the photo-generated electrons and holes.CO_(2)-TPD results imply that the amounts and stability of heterojunctions are enhanced compared with their counterparts.The Bi_(2)Al_(4)O_(9)/β-Bi_(2)O_(3)heterojunction with 14 mol%Bi_(2)Al_(4)O_(9)shows the highest photocatalytic ability for reduction of CO_(2)into CO.The enhanced photoreduction of CO_(2)performance can be ascribed to the synergistic effects of the heterojunction for electron separation and oxygen vacancies for CO_(2)activation.

Development strategies and improved photocatalytic CO_(2) reduction performance of metal halide perovskite nanocrystals

In recent years,photocatalytic CO_(2)reduction reaction(CRR) has attracted much scientific attention to overcome energy and environmental issues by converting CO_(2)into high-value-added chemicals utilizing solar energy.Metal halide perovskite(MHP) nanocrystals(NCs) are recognized as an ideal choice for CRR owing to their outstanding optoelectronic properties.Although great efforts have been devoted to designing more effective photocatalysts to optimize CRR performance,severe charge recombination,instability,and unsatisfactory activity have become major bottlenecks in developing perovskite-based photocatalysts.In this review,we mainly focus on the recent research progress in the areas of relevance.First,a brief insight into reaction mechanisms for CRR and structural features of MHPs are introduced.Second,efficient modification approaches for the improvement of the photocatalytic activity and stability of the perovskite-based catalysts are comprehensively reviewed.Third,the state-of-the-art achievements of perovskite-based photocatalysts for CRR are systematically summarized and discussed,which are focused on the modification approaches,structure design,and the mechanism of the CO_(2)reduction process.Lastly,the current challenges and future research perspectives in the design and application of perovskite materials are highlighted from our point of view to provide helpful insights for seeking breakthroughs in the field of CRR.This review may provide a guide for scientists interested in applying perovskite-based catalysts for solar-to-chemical energy conversion.

Cu-Based Materials for Enhanced C_(2+) Product Selectivity in Photo-/Electro-Catalytic CO_(2) Reduction: Challenges and Prospects

Carbon dioxide conversion into valuable products using photocatalysis and electrocatalysis is an effective approach to mitigate global environmental issues and the energy shortages. Among the materials utilized for catalytic reduction of CO_(2), Cu-based materials are highly advantageous owing to their widespread availability, cost-effectiveness, and environmental sustainability. Furthermore, Cu-based materials demonstrate interesting abilities in the adsorption and activation of carbon dioxide, allowing the formation of C_(2+) compounds through C–C coupling process. Herein, the basic principles of photocatalytic CO_(2) reduction reactions(PCO_(2)RR) and electrocatalytic CO_(2) reduction reaction(ECO_(2)RR) and the pathways for the generation C_(2+) products are introduced. This review categorizes Cu-based materials into different groups including Cu metal, Cu oxides, Cu alloys, and Cu SACs, Cu heterojunctions based on their catalytic applications. The relationship between the Cu surfaces and their efficiency in both PCO_(2)RR and ECO_(2)RR is emphasized. Through a review of recent studies on PCO_(2)RR and ECO_(2)RR using Cu-based catalysts, the focus is on understanding the underlying reasons for the enhanced selectivity toward C_(2+) products. Finally, the opportunities and challenges associated with Cu-based materials in the CO_(2) catalytic reduction applications are presented, along with research directions that can guide for the design of highly active and selective Cu-based materials for CO_(2) reduction processes in the future.

Synergy of photocatalytic reduction and adsorption for boosting uranium removal with PMo_(12)/UiO-66 heterojunction

In this work,we proposed a new U(Ⅵ)removal strategy combining adsorption and photocatalytic reduction by the PMo_(12)/UiO-66 heterojunctions.The PMo_(12)has been encapsulated in the cavities of Ui O-66 by a one-step hydrothermal method,and the PMo_(12)/UiO-66 exhibited high adsorption capacity and photocatalytic activity.The maximal theoretical sorption capacity of U(Ⅵ)on 15%PMo_(12)/UiO-66 reached225.36 mg/g and the photoreduction rate of 15%PMo_(12)/UiO-66 is about thirty times as much as UiO-66.Under the light irradiation,the photogenerated electrons rapidly transport from UiO-66 to PMo_(12),and the photo-generated electrons could efficiently reduce the pre-enriched U(Ⅵ)to U(IV).This work provides new insights into remediation of the radioactive environment.

Efficient photocatalytic reduction of chromium(Ⅵ) using photoreduced graphene oxide as photocatalyst under visible light irradiation

Graphene oxide(GO),a new and promising material,has been widely used as a co-catalyst in photocatalytic reactions;however,its capacity as a sole photocatalyst has rarely been investigated.In this study,ultraviolet(UV) light irradiation was used as a modification method to obtain reduced GO(rGO) samples.The samples were used as photocatalysts to examine their visible light photocatalytic activity toward hexavalent chromium(Cr(Ⅵ)) removal.Atomic force microscopy(AFM),X-ray diffraction(XRD),UV-vis spectrophotometry,Raman spectroscopy,X-ray photoelectron spectroscopy(XPS),and electron spin resonance(ESR) spectroscopy were applied to interpret the surface and structure changes with UV irradiation.The oxygen-containing functional groups(OFGs) on the GO surface were reduced to defective carbons andπ-conjugated C=C(sp^(2) domains) under UV light;this led to a decrease in the interlayer distance between GO sheets,GO fragmentation,and increased disorder on the GO surface.The restoration of sp^(2) domains led to a narrower band gap of GO,which favored the rGO excitation by visible light to generate electron-hole pairs.The rGO pre-irradiated with UV for 1 h(rGO-1),possessing the highest defect density and electron generation efficiency,exhibited the best Cr(Ⅵ) reduction efficiency,which was about three times that of the GO sample;moreover,it outperformed most of the reported GO-based nanomaterials.In addition,low pH and the addition of citric acid as a hole scavenger could further improve the photocatalytic activity.This study proves that GO or rGO can be used as a sole photocatalyst under visible light to remove environmental pollutants such as heavy-metal ions,and it paves the way for the development of this kind of material and its UV-irradiation modification for further applications.

Photocatalytic reduction of Cr(Ⅵ)by WO_(3)@PVP with elevated conduction band level and improved charge carrier separation property

Photocatalytic reduction of heavy metal ions is a green and promising technology which requires electrons with enough negative energy levels as well as efficient separation property from photo-generated holes of photocatalysts.For WO_(3),the low conduction band edge and the severe photo-generated charge carrier recombination limited its application in photocatalytic reduction of pollutants.In this work,we prepared WO_(3)@PVP with PVP capped WO_(3) by a simple one-step hydrothermal method,which showed an elevated energy band structure and improved charge carrier separation property.XRD,SEM,TEM,XPS,DRS,and the photocurrent density test were carried out to study the properties of the composite.Results demonstrated monoclinic WO_(3) with a size of~100-250 nm capped by PVP was obtained,which possessed fewer lattice defects inside but more defects(W^(5+))on the surface.Moreover,the results of the photocatalytic experiment showed the kinetic constant of Cr(Ⅵ)reduction process on WO_(3)@PVP was 0.532 h^(-1),which was 3.1 times higher than that onWO_(3)(0.174 h^(-1)),demonstratingWO_(3)@PVP with good photocatalytic capability for Cr(Ⅵ)reduction.This can be attributed to the improved charge carrier separation performance,the improved adsorption capacity and the elevated conduction band edge of WO_(3)@PVP.More importantly,the energy band structure of WO_(3)@PVP was proved elevated with a value as high as 1.14 eV than that of WO_(3) nanoparticles,which enables WO_(3)@PVP a promising material in the photocatalytic reduction reaction of heavy metal ions from wastewater.

Modulating the Selectivity of Photocatalytic CO_(2)Reduction in Barium Titanate by Introducing Oxygen Vacancies

Artifi cial photosynthetic reduction of CO_(2) into valuable chemicals is one of the most promising approaches to solve the energy crisis and decreasing atmospheric CO_(2) emissions.However,the poor selectivity accompanied by the low activity of photocatalysts limits the development of photocatalytic CO_(2) reduction.Herein,inspired by the use of oxygen vacancy engi-neering to promote the adsorption and activation of CO_(2) molecules,we introduced oxygen vacancies in the representative barium titanate(BaTiO 3)photocatalyst for photocatalytic CO_(2) reduction.We found that oxygen vacancies brought signifi cant diff erences in the CO_(2) photoreduction activity and selectivity of BaTiO 3.The intrinsic BaTiO 3 showed a low photocatalytic activity with the dominant product of CO,whereas BaTiO 3 with oxygen vacancies exhibited a tenfold improvement in photocatalytic activity,with a high selectivity of~90%to CH 4.We propose that the presence of oxygen vacancies promotes CO_(2) and H 2 O adsorption onto the BaTiO 3 surface and also improves the separation and transfer of photogenerated carriers,thereby boosting the photocatalytic CO_(2) reduction to CH 4.This work highlights the essential role of oxygen vacancies in tuning the selectivity of photocatalytic reduction of CO_(2) into valuable chemicals.

Visible-light deposition of CrO_(x) cocatalyst on TiO_(2):Cr valence regulation for superior photocatalytic CO_(2)reduction to CH_(4)

Photodeposition is widely adopted for implanting metal/metal oxide cocatalysts on semiconductors.However,it is prerequisite that the photon energy should be sufficient to excite the host semiconductor.Here,we report a lower-energy irradiation powered deposition strategy for implanting CrO_(x) cocatalyst on TiO_(2).Excitingly,CrO_(x)-400 implanted under visible-light irradiation significantly promotes the CH4 evolution rate on TiO_(2)to 8.4μmolg·^(-1)h^(-1) with selectivity of98%from photocatalytic CO_(2)reduction,which is 15 times of that on CrO_(x)-200 implanted under UV-visible-light irradiation.Moreover,CrO_(x)-400 is identified to be composed of higher valence Cr species compared to CrO_(x)-200.This valence states regulation of Cr species is indicated to provide more active sites for CO_(2) adsorption/activation and to modulate the reaction mechanism from single Cr site to Cr-Cr dual sites,thus endowing the superior CH_(4)production.This work demonstrates an alternative strategy for constructing efficient metal oxides cocatalysts on wide bandgap semiconductor.

Regulation of excitation energy transfer in Sb-alloyed Cs_(4)MnBi_(2)Cl_(12) perovskites for efficient CO_(2) photoreduction to CO and water oxidation toward H_(2)O_(2)

Lead(Pb)-free halide perovskites have recently attracted increasing attention as potential catalysts for CO_(2) photoreduction to CO due to their potential to capture solar energy and drive catalytic reaction.However,issues of the poor charge transfer still remain one of the main obstacles limiting their performance due to the overwhelming radiative and nonradiative charge-carrier recombination losses.Herein,Pb-free Sb-alloyed all-inorganic quadruple perovskite Cs_(4)Mn(Bi_(1-x)Sb_(x))_(2)Cl_(12)(0≤x≤1)is synthesized as efficient photocatalyst.By Sb alloying,the undesired relaxation of photogenerated electrons from conduction band to emission centers of[MnCl6]^(4-)is greatly suppressed,resulting in a weakened PL emission and enhanced charge transfer for photocatalyst.The ensuing Cs_(4)Mn(Bi_(1-x)Sb_(x))_(2)Cl_(12) photocatalyst accomplishes efficient conversion of CO_(2)into CO,accompanied by a surprising production of H_(2)O_(2),a high valueadded product associated with water oxidation.By optimizing Sb^(3+) concentration,a high CO evolution rate of 35.1μmol g^(-1)h^(-1)is achieved,superior to most other Pb and Pb-free halide perovskites.Our findings provide new insights into the mixed-cation alloying strategies for improved photocatalytic performance of Pb-free perovskites and shed light on the rational design of robust band structure toward efficient energy transfer.

The photo-decomposition and self-restructuring dynamic equilibrium mechanism of Cu_(2)(OH)_(2)CO_(3)for stable photocatalytic CO_(2)reduction

Developing suitable photocatalysts and understanding their intrinsic catalytic mechanism remain key challenges in the pursuit of highly active,good selective,and long-term stable photocatalytic CO_(2)reduction(PCO_(2)R)systems.Herein,monoclinic Cu_(2)(OH)_(2)CO_(3)is firstly proven to be a new class of photocatalyst,which has excellent catalytic stability and selectivity for PCO_(2)R in the absence of any sacrificial agent and cocatalysts.Based on a Cu_(2)(OH)_(2)^(13)CO_(3)photocatalyst and 13CO_(2)two-sided^(13)C isotopic tracer strategy,and combined with in situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS)analysis and density functional theory(DFT)calculations,two main CO_(2)transformation routes,and the photo-decomposition and self-restructuring dynamic equilibrium mechanism of Cu_(2)(OH)_(2)CO_(3)are definitely revealed.The PCO_(2)R activity of Cu_(2)(OH)_(2)CO_(3)is comparable to some of state-of-the-art novel photocatalysts.Significantly,the PCO_(2)R properties can be further greatly enhanced by simply combining Cu_(2)(OH)_(2)CO_(3)with typical TiO_(2)to construct composites photocatalyst.The highest CO_(2)and CH_(4)production rates by 7.5 wt%Cu_(2)(OH)_(2)CO_(3)-TiO_(2)reach 16.4μmol g^(-1)h^(-1)and 116.0μmol g^(-1)h^(-1),respectively,which are even higher than that of some of PCO_(2)R systems containing sacrificial agents or precious metals modified photocatalysts.This work provides a better understanding for the PCO_(2)R mechanism at the atomic levels,and also indicates that basic carbonate photocatalysts have broad application potential in the future.

C-doped BiOCl/Bi_(2)S_(3) heterojunction for highly efficient photoelectrochemical detection and photocatalytic reduction of Cr(VI)

Novel C-BiOCl/Bi_(2)S_(3) composites are prepared by hydrothermal C doping in BiOCl and in-situ growth of Bi_(2)S_(3) on C-BiOCl.Compared with BiOCl,C-BiOCl has a larger exposed surface area and can effectively absorb visible light.The construction of a heterojunction in C-BiOCl/Bi_(2)S_(3) further promotes the separation and transfer of photogenerated carriers.With improved photoelectric properties,the optimized 5C-BiOCl/5Bi_(2)S_(3) is applied as a dual-functional composite for photoelectrochemical(PEC)detection and photocatalytic(PC)reduction of Cr(VI).The 5C-BiOCl/5Bi_(2)S_(3) shows a linear range of 0.02-80μM for PEC cathodic detection of Cr(VI)with a detection limit of 0.01628μM.Additionally,99.5%of Cr(VI)can be removed via absorption and PC reduction by 5C-BiOCl/5Bi_(2)S_(3),with the reduction rate constant(k)336 times higher than that of BiOCl.

Construction of ZnO@CDs@Co_(3)O_(4) sandwich heterostructure with multi-interfacial electron-transfer toward enhanced photocatalytic CO_(2) reduction

Photocatalytic conversion of CO_(2) into small-molecule chemical feedstocks can meet the growing demand for energy and alleviate the global warming. Herein, a p-n ZnO@CDs@Co_(3)O_(4) heterojunction with sandwich structure was constructed by calcination method of self-assembled ZIF-8@CDs@ZIF-67. The ZnO@CDs@Co_(3)O_(4) with well-defined interfacial structure exhibited the significantly enhanced photocatalytic CO_(2) reduction activity, and the optimal catalyst indicated the(CO + CH_(4)) evolution rate of 214.53μmol g^(-1)h^(-1) under simulated solar light, which was superior to ZnO, Co_(3)O_(4) and binary ZnO@Co_(3)O_(4).The internal cavity, exposed active sites, multiple interfaces and constructed p-n heterojunction can facilitate the light harvesting and photoexcited electron transfer. Besides, after introduction of CDs placed in the middle layer between ZnO and Co_(3)O_(4), CDs with excellent photoelectric property further promoted charge separation and migration. This work represents an appealing strategy to construct well-defined photocatalysts for boosting CO_(2) photoreduction.

Evaluation of the plasmonic effect of Au and Ag on Ti-based photocatalysts in the reduction of CO2 to CH4

Crystalline TiO_2(P25) and isolated titanate species in a ZSM-5 structure(TS-1) were modified with Au and Ag, respectively, and tested in the gas-phase photocatalytic CO_2 reduction under high purity conditions. The noble metal modification was performed by photodeposition. Light absorbance properties of the catalysts are examined with UV–Vis spectroscopy before and after the activity test. In the gas-phase photocatalytic CO_2 reduction, it was observed that the catalysts with Ag nanostructures are more active than those with Au nanostructures. It is thus found that the energetic difference between the band gap energy of the semiconductor and the position of the plasmon is influencing the photocatalytic activity.Potentially, plasmon excitation due to visible light absorption results in plasmon resonance energy, which affects the excitation of the semiconductor positively. Therefore, an overlap between band gap energy of the semiconductor and metal plasmon is needed.

Self-template-oriented synthesis of lead-free perovskite Cs_(3)Bi_(2)I_(9) nanosheets for boosting photocatalysis of CO_(2) reduction over Z-scheme heterojunction Cs_(3)Bi_(2)I_(9)/CeO_(2)

Lead halide perovskite (LHP) nanocrystals have been intensely studied as photocatalysts for artificial photosynthesis in recent years.However,the toxicity of lead in LHP seriously limits their potential for widespread applications.Herein,we first present the synthesis of 2D lead-free halide perovskite (Cs_(3)Bi_(2)I_(9)) nanosheets with self-template-oriented method,in which BiOI/Bi_(2)O_(2) nanosheets were used as the template and Bi ion source simultaneously.Through facile electrostatic self-assembly strategy,a Z-scheme heterojunction composed of Cs_(3)Bi_(2)I_(9)nanosheets and CeO_(2) nanosheets (Cs_(3)Bi_(2)I_(9)/CeO_(2)-3:1) was constructed as photocatalyst for the photo-reduction of CO_(2) coupled with the oxidation of H_(2)O.Due to the matching energy levels and the close interfacial contact between Cs_(3)Bi_(2)I_(9)and CeO_(2) nanosheets,the separation efficiency of the photogenerated carriers in Cs_(3)Bi_(2)I_(9)/CeO_(2)-3:1 composite was significantly improved.Consequently,the environment-friendly halide perovskite heterojunction Cs_(3)Bi_(2)I_(9)/CeO_(2)-3:1presents impressive photocatalytic activity for the reduction of CO_(2)to CH_(4)and CO with an electron consumption yield of 877.04μmol g^(-1),which is over 7 and 15 times higher than those of pristine Cs_(3)Bi_(2)I_(9)and CeO_(2)nanosheets,exceeding the yield of other reported bismuth-based perovskite for photocatalytic CO_(2)reduction.

Regulating^(*)COOH intermediate via amino alkylation engineering for exceptionally effective photocatalytic CO_(2) reduction

Photocatalytic reduction of CO_(2) into fuel represents a promising approach for achieving carbon neutrality,while realizing high selectivity in this process is challenging due to uncontrollable reaction intermediate and retarded desorption of target products.Engineering the interface microenvironment of catalysts has been proposed as a strategy to exert a significant influence on reaction outcomes,yet it remains a significant challenge.In this study,amino alkylation was successfully integrated into the melem unit of polymeric carbon nitrides(PCN),which could efficiently drive the photocatalytic CO_(2) reduction.Experimental characterization and theoretical calculations revealed that the introduction of amino alkylation lowers the energy barrier for CO_(2) reduction into^(*)COOH intermediate,transforming the adsorption of^(*)COOH intermediate from the endothermic to an exothermic process.Notably,the as-prepared materials demonstrated outstanding performance in photocatalytic CO_(2) reduction,yielding CO_(2)at a rate of 152.8μmol h^(-1) with a high selectivity of 95.4%and a quantum efficiency of 6.6%.

Effects of surface chlorine atoms on charge distribution and reaction barriers for photocatalytic CO_(2)reduction

Photocatalytic CO_(2)reduction to produce high value-added carbon-based fuel has been proposed as a promising approach to mitigate global warming issues.However,the conversion efficiency and product selectivity are still low due to the sluggish dynamics of transfer processes involved in proton-assisted multi-electron reactions.Lowering the formation energy barriers of intermediate products is an effective method to enhance the selectivity and productivity of final products.In this study,we aim to regulate the surface electronic structure of Bi_(2)WO_(6)by doping surface chlorine atoms to achieve effective photocatalytic CO_(2)reduction.Surface Cl atoms can enhance the absorption ability of light,affect its energy band structure and promote charge separation.Combined with DFT calculations,it is revealed that surface Cl atoms can not only change the surface charge distribution which affects the competitive adsorption of H_(2)O and CO_(2),but also lower the formation energy barrier of intermediate products to generate more intermediate*COOH,thus facilitating CO production.Overall,this study demonstrates a promising surface halogenation strategy to enhance the photocatalytic CO_(2)reduction activity of a layered structure Bi-based catalyst.

Highly selective photocatalytic CO_(2) reduction to ethylene in pure water by Nb_(2)O_(5) nanoparticles with enriched surface –OH groups under simulated solar illumination

Photocatalytic CO_(2) reduction to valuable chemical compounds could be a promising approach for carbon-neutral practice.In this work,a simple and robust thermal decomposition process was developed with ammonium carbonate((NH4)2CO3)as both precipitation agent and sacrificial template to produce fine Nb_(2)O_(5) nanoparticles with the rich existence of surface hydroxyl(–OH)groups.It was found by density functional theory(DFT)calculations and experiments that the rich existence of the surface–OH groups enhanced the adsorption of both reactants(CO_(2) and H_(2)O molecules)for the photocatalytic CO_(2) reduction on these fine Nb_(2)O_(5) nanoparticles,and the highly selective conversion of CO_(2) to the high-value chemical compound of ethylene(C_(2)H_(4),~68μmol·g^(−1)·h^(−1) with~100%product selectivity)was achieved under simulated solar illumination without usage of any sacrificial agents or noble metal cocatalysts.This synthesis process may also be readily applied as a surface engineering method to enrich the existence of the surface–OH groups on various metal oxide-based photocatalysts for a broad range of technical applications.

Accelerating solar driven CO_(2) reduction via sulfur-doping boosted water dissociation and proton transfer

Exploring efficient photocatalysts for solar driven CO_(2) reduction with water(H_(2)O)as a proton donor is highly imperative but remains a great challenge because the synchronous enhancement of CO_(2) activation,H_(2)O dissociation and proton transfer is hardly achieved on a photocatalyst.Particularly,the sluggish H_(2)O dissociation impedes the photocatalytic CO_(2) reduction reaction involving multiple proton–electron coupling transfer processes.Herein,a sulfur-doped BiOCl(S-BiOCl)photocatalyst with abundant oxygen vacancies(OV)is developed,which exhibits broadband-light harvesting across solar spectrum and distinct photothermal effect due to photochromism.For photocatalytic CO_(2) reduction with H_(2)O in a gas–solid system,the high CO yield of 49.76μmol·g_(cat)^(-1)·h^(-1) with 100%selectivity is achieved over the S-BiOCl catalyst under a simulated sunlight.The H_(2)O-assisted CO_(2) reduction reaction on S-BiOCl catalyst is triggered by photocatalysis and the photothermal heating further enhances the reaction rate.The kinetic isotope experiments indicate that the sluggish H_(2)O dissociation affects the whole photocatalytic CO_(2) reduction process.The presence of oxygen vacancies promotes the adsorption and activation of H_(2)O and CO_(2),and the doped S sites play a crucial role in boosting H_(2)O dissociation and accelerating the dynamic migration of hydrogen species.As a result,the ingenious integration of OV defects,S sites and photothermal effect in S-BiOCl catalyst conjointly contributes to the significant improvement in photocatalytic CO_(2) reduction performance.