Preparation And Modification Of Photoanode Based On Tungsten Trioxide And Its Application In Photoelectric Catalysis

With the development of industrial society and the progress of human production,environmental pollution and energy shortage have gradually become two important factors that hinder the development progress,and the search and development of new environmentally friendly energy sources has become one of the hot topics at this stage.Photoelectrochemical(PEC)technology can effectively degrade environmental pollutants and has a wide range of applications in the field of new solar energy utilization,PEC technology can effectively separate photogenerated electrons from holes by means of applied bias,which can achieve rapid reaction with less solar energy.This has attracted the attention of researchers in the environmental and energy fields as it greatly enhances the efficiency of solar energy utilization.WO₃ is one of the most common photocatalytic anode materials and is a typical n-type semiconductor,which has a wide response range to sunlight and exhibits considerable light absorption capability in the visible range and a suitable band gap width of about 2.6 eV for photocatalytic reactions.However,there are still some limitations in the photocatalytic efficiency of WO₃,such as the difficulty of effective separation of photogenerated electrons and holes of the material,easy compounding,and low photocatalytic efficiency.In this thesis,the modification of WO₃ photoanodes by using surface polarization,structure optimization and surface kinetics optimization has greatly improved the photocatalytic performance of tungsten oxide photoanodes and systematically investigated its photocatalytic mechanism,the main research contents include.1.The WO₃/BFO core-shell composite electrode material was prepared by depositing bismuth ferrate BiFeO₃(BFO)with ferroelectric properties on the surface of WO₃ nanosheet electrode through a simple spin-coating method,and used as a photoanode to construct a PEC system to test its photocatalytic water decomposition performance,and the mechanism of the influence of the ferroelectric properties of BFO on the photocatalytic activity of WO₃ photoanode was systematically investigated.The results of XRD,XPS,SEM and TEM showed that the BFO could be uniformly deposited on the surface of WO₃ nanosheet photoanode by spin coating method and a BFO shell layer with a thickness of 20-30 nm was formed on the surface of WO₃ nanoplan.The photocurrent density appears significantly enhanced and the stability is improved to about 2.83 m A cm^-2 at an external voltage of0.6 V vs Ag/AgCl,which is about 244%higher than that of WO₃ under simulated solar illumination at AM 1.5.The results of Mott-Schottky tests,intensity modulated photoelectrochemical spectroscopy and transient photocurrent decay show that BFO ferroelectric nanoshell layer can significantly enhance the charge density of WO₃/BFO,enhance its charge transport efficiency and separation performance as well as prolong the charge lifetime,which may be the main reason for the enhanced photocatalytic decomposition of aquatic hydrogen and oxygen production activity of WO₃/BFO.2.Nickel-iron bimetallic hydroxide(NiFe-LDH)shell layer was deposited on the surface of WO₃ nanosheet photoanode material by electrodeposition,and a series of WO₃/LDH composite photoanodes were prepared by regulating the time of electrodeposition.The WO₃/LDH composite photoanode has a high photocurrent density at an external voltage of 0.6 V vs Ag/AgCl and exhibits good stability up to2.32 m A cm^-2,with approximately 114%enhancement over WO₃ under AM 1.5simulated solar illumination.The results of PL tests and UV analysis tests show that the NiFe-LDH shell layer can provide more reactive sites and can effectively reduce the electron-hole complex,which is the main reason for the greatly enhanced photoelectrochemical properties of WO₃/LDH composite photoanode.In summary,the modification of WO₃ photoanode can effectively improve the photoelectric conversion efficiency of the material while suppressing the compounding of photogenerated carriers in the system,thus significantly improving the efficiency of the whole PEC system.The modified deposition of WO₃semiconductor material as a substrate successfully promotes the charge separation and improves the efficiency of solar energy usage,which can effectively degrade organic matter and generate clean energy-hydrogen under visible light response.This work not only provides a way to solve the environmental pollution problem,but also presents a feasible and constructive idea to deal with the resource shortage problem.