Modification And Structural Characterization Of Bismuth Vanadate Photoanode And Its Photocatalytic Hydrogen Production From Wate

With the development of natural science and world economy,energy technology has been incorporated into the development of many countries in the world.However,over the past 100years the energy consumption of countries has been dominated by fossil fuels,and scientists predict that global electricity consumption will double by 2050.The massive use of non-renewable energy will cause serious environmental problems and ecological crisis.Therefore,the development of efficient renewable energy alternatives to fossil fuels has aroused people’s attention.Among many solutions,the technology of photochemical（PEC）water decomposition to produce hydrogen has become one of the most promising solutions.Semiconductor materials play a key role in the technology center of photochemistry（PEC）,so it is very important to design and develop semiconductor photoelectrodes with excellent performance.Among many photoelectrode materials,Bismuth vanadate（BiVO₄）is considered to be the most promising photoanode semiconductor material due to its strong catalytic ability of oxygen generation due to the overlap of Bi 6p orbital and V 3d-O 2p orbital.Unfortunately,the rapid recombination and poor stability of photogenerated electron-hole pairs limit the PEC performance.To solve these problems,doping,heterojunction construction,oxygen evolution catalyst support and other methods were used to modify the photochemical water decomposition performance to improve.It provides theoretical basis and experimental basis for the preparation of efficient and stable PEC water decomposition photoelectrode for hydrogen production.（1）The impurity element Fe was introduced into BiVO₄ by a simple method,and the incorporation amount of the impurity element Fe was optimized through experiments,and the optimal doping amount of 1%was finally determined.Fe-BiVO₄/Co O_X X-ray anode was prepared by loading Co O_X cocatalyst on the surface of Fe-BiVO₄ photoanode.The photocurrent density of the photoanode reached 4.0 m A cm^-2 at 1.23 V vs.RHE under the irradiation of an AM 1.5G solar simulator.In addition,the photoanode showed excellent stability for 10 h in the stability test.The experimental results show that the introduction of Fe and Co O_X load effectively improve the charge transfer and charge separation of BiVO₄ photoanode,inhibit the surface recombination of photogenerated electron-hole,and reduce the charge transfer resistance between the semiconductor and electrolyte interface.In addition,Co O_X load can not only effectively protect the electrode to reduce VO₄³⁺ionic dissolution caused by photocorrosion,but also provide more active sites for water oxidation reaction,making Fe-BiVO₄/Co O_X X-ray anode show excellent PEC water oxidation performance.（2）Fe OCl/BiVO₄ type-Ⅱheterojunction was constructed by chemical bath deposition and annealing treatment,and then Fe Ni O_X bimetallic oxygen evolution cocatalyst was electrodeposited to prepare high performance Fe Ni O_X/Fe OCl/BiVO₄ photoanode.The Fe Ni O_X/Fe OCl/BiVO₄ photoanode showed excellent photochemical performance at 1.23 V vs.RHE under AM 1.5G illumination,and the photocurrent density reached 6.7 m A cm^-2,3.4 times higher than the original BiVO₄ photocurrent density.In addition,the stability of the Fe Ni O_X/Fe OCl/BiVO₄ photoanode was tested without the addition of any other component boric acid buffer solution.The Fe Ni O_X/Fe OCl/BiVO₄ photoanode showed excellent stability for up to 80 h at 0.8 V vs.RHE external bias.The experimental results show that Fe OCl type-n semiconductors have a thermodynamic matching band structure with BiVO₄,and the two semiconductors contact to form type-Ⅱheterojunction,which effectively improves the transfer efficiency and separation efficiency of photogenerated electrons in BiVO₄-based photoanode.Electrodeposition of amorphous Fe Ni O_X can not only rapidly extract the accumulated holes on the photoanode surface,but also increase the adsorption of OH^-on the photoanode,providing more reaction sites for the reaction and accelerating the water oxidation reaction.In addition,Fe Ni O_X can fully protect the photoanode,reduce the impact of photocorrosion on the photoanode,and enhance the stability of the photoanode.