Study On Performance Improvement Strategy And Application Of Bismuth Vanadate Photoanode

With the development of human society,the consumption of fossil energy is increasing fastly.The fossil energy is non-renewable and causes a lot of greenhouse gas and environmental pollution.As an environmental-friendly technology that can convert solar energy into chemical energy,semiconductor photoelectrochemical can split water to produce hydrogen,reduce nitrogen to produce ammonia,reduce carbon dioxide to produce high value-added chemicals and selective transform organic matter by using solar energy.It is regarded as an ideal method to solve the energy crisis and environmental pollution.The theoretical solar energy conversion efficiency of semiconductor photoelectrochemistry is as high as about 30%,which can meet the needs for clean energy in modern society.However,the current semiconductor photoelectrochemical solar energy conversion efficiency is still far from industrial application and the preparation cost is high.These factors greatly limit the application prospects of photoelectrochemical.However,the slow kinetic process of photoelectrochemical water splitting for oxygen production and the low value of oxygen limits the industrial application of photoelectrochemistry.Therefore,it is urgent to expand the types of semiconductor photoelectrochemical reactions to obtain more value-added products and improve the photoelectrochemical solar energy conversion efficiency.In order to improve the semiconductor photoelectrochemical solar energy conversion efficiency,we chose the BiVO4 photoanode with good visible light absorption,suitable band structure,high photoelectrochemical activity and stability as the main research object.Aiming at the solar spectral response range,carrier separation efficiency and catalytic reaction efficiency of the semiconductor photoelectrode,we use stress engineering strategy,surface cocatalyst loading,catalytic reaction active site design,surface plasmon resonance effect design and other means to prepare high-efficiency BiVO4 photoelectrode and apply them in photoelectrochemical water splitting,organic matter conversion,nitrogen reduction,to improve solar energy conversion efficiency.The specific research contents are as following:In chapter 1,the basic principles of semiconductor photoelectrochemistry and common types of photoelectrochemical reactions were described.Then,the important parameters,influencing factors and control strategies were introduced.Then the research progress of semiconductor photoelectrochemistry,the key scientific problems and the basic properties of BiVO4 were introduced.Finally,the significance and research content of this paper were clarified.In chapter 2,the stress was introduced into BiVO4 photoanode by stress engineering strategy and the stress was adjusted by changing the temperature to improve the carrier separation efficiency and surface photovoltage of BiVO4 photoanode,and then obtained excellent photoelectrochemical water splitting properties.Then,metastable high-pressure tetragonal phase T-BiVO4 nanomaterials were prepared by quenching process.The stress in TBiVO4 changed its energy banding structure and realized the photocatalytic water splitting to produce hydrogen and oxygen.In chapter 3,a new method of cocatalyst surface loading photoanode was designed by using the strong adhesion of polydopaminer and the characteristics of chelating metal ions.The carriers separation efficiency of BiVO4 photoanode is significantly improved,thereby improving the photoelectrochemical water splitting properties of the photoanode.The photoelectrochemical activity of photoelectrochemical 5-hydroxymethylfurfural oxidation was improved by using the cocatalysts as catalytically-active sites.Finally,the universality of this cocatalyst surface loading strategy was explored,and the photoelectrochemical water splitting properties was improved when it was extended to other semiconductor photoanode(TiO2,Fe2O3).In chapter 4,Au/KxMoO3 nanoarrays with localized surface plasmon resonance were applied for photoelectrochemical nitrogen reduction reaction.The ohmic contact between Au nanoparticles and KxMoO3 resulted in the effective transfer of hot electrons in KxMoO3 nanoarrays to Au nanoparticles.Au nanoparticles as catalytically-active site reduced the free energy of N2 adsorption and activation,and resulted in excellent photoelectrochemical nitrogen reduction performance.Then,we constructed a photovoltaic-photoelectrochemical coupling system to realize unbiased photoelectrochemical water oxidation to produce oxygen and nitrogen reduction to produce ammonia.In chapter 5,it summarized the main research contents and innovations of this paper.Then we analyzed the problems and deficiencies of this paper.Furtherly,we look forward to the future research directions according to these problems and deficiencies.