Preparation Of High Efficient Bismuth Vanadate Photoanodes And Study On The Photoelectrochemical Water Splitting Performance

With the continuous development of China's economy,energy consumption is increasing day by day,and seriou environmental pollution is accompanying with it.Therefore,it is urgent to find a new green clean energy that can replace traditional fossil fuels.Because of its high energy density,hydrogen energy has zero pollution to the environment due to direct combustion of water,and is considered as a new type of clean energy with the greatest development potential.Photoelectrocatalytic decomposition of water to produce hydrogen is an effective way by using solar energy to convert chemical energy to crack water into oxygen and hydrogen.Since only sunlight and water are needed in this process,and no pollution is generated,photocatalytic water decomposition has received widespread attention in the international community in recent years.The conversion efficiency of photocatalytic water decomposition is mainly determined by the absorption of anode light,the separation of internal carriers,and the transport of interfacial carriers.Improving the efficiency of interfacial carrier transport can be achieved by loading an effective catalyst on the surface of the anode material.The absorption of light can be effectively increased by increasing the thickness of the anode material.However,increasing the thickness of photoanode,the internal separation efficiency will decrease due to the poor transport resulted from the short diffusion length of charge in photoanode.Therefore,how to further improve the efficiency of these two has become the key issue of the current photoelectrochemical decomposition of water conversion efficiency,and it is also the focus of the next research of photoelectrochemical decomposition of water to produce hydrogen.Aiming at the above problems and the basic principles of photocatalysis,we mainly improve the internal photoelectric transmission efficiency by doping the anode material internally,loading an effective catalyst,and constructing a new composite structure to improve the internal photovoltaic conversion efficiency.The specific research content is as follows:In the first chapter,in order to understand the theoretical knowledge of the catalysis and the basic operation of the experiment,we did some basic electrochemical work to prepare for the study of photocatalysis,that is,for the study of the electrocatalytic performance of WP,the integrated WP₂ nanosheets array on W foil?WP₂ NSs/W?electrode is synthesized via an in situ two-step growth strategy.We successfully synthesized WP petal-shaped nanosheets on W foil for the first time.With the exposure of high-density active sites,WP₂ NSs/W showed excellent HER activity.When the current density was 10 m A/cm² in alkaline.The low starting point potential is approximately 0 V and the overpotential is only 90 m V.In Chapter 2,we synthesized a petal-shaped bismuth vanadate?BVO?enriched with oxygen defects on FTO conductive glass by a new CVD synthesis method for the first time after learning some catalytic theory and experimental operations.It has been proved that the internal transmission efficiency of photo-generated carriers can be effectively improved.Its photocurrent density is 3.25 m A/cm²,and the IPCE is close to 90%.In Chapter 3,we use P-type graphene as a hole extraction layer to provide a high-density state at the interface of the insulator without reducing light absorption.Construct FTO/BVO/Ti O₂/Graphene/Ni to effectively improve.The hole tunneling efficiency of bismuth vanadate MIS devices is presented.Compared with other bismuth vanadate photoanodes reported in the literature,this photoanode composite structure shows the highest PEC activity and stability in a strong alkaline?KOH solution?electrolyte,with a photocurrent density of about 2.72 m A/cm² and no significant attenuation of current after 30 hours.