Structure Regulation And Properties Of CuO_x Nanowire Array Photoelectrodes

Looking back on the whole process of human social development,energy transformation has been closely linked to social progress and development.Photoelectrochemical water splitting device can convert solar energy into clean and sustainable hydrogen fuel to solve the current energy shortage.It is an efficient green energy system that integrates solar energy conversion and storage.However,the most important thing in this system is to prepare highly efficient and stable electrode materials.Up to now,N-type metal oxide photoanodes such as TiO₂,WO₃,Fe₂O₃,BiVO₄ have been extensively studied,but the research on P-type metal oxide is still superficial and needs further development and research.This thesis mainly discusses the regulation,preparation,characterization and application in photoelectrochemical water splitting of photocathode micro/nano structure based on copper oxide:CuO nanowire and Cu₂O/TiO₂ heterojunction.The first part focuses on the development of high-efficiency CuO nanowire photocathodes.High activity photocathode with micro-nano structure was prepared by a simple electrochemical anodic oxidation method and by adjusting and controlling the CuO nanowires based on copper.In the second part,TiO₂ was deposited on Cu₂O nanowires by different deposition methods,and Cu₂O/TiO₂ heterojunction was discussed as a visible light responsive photocatalyst.The specific contents and results are as follows:1.CuO nanowire photocathodes are regulated and controlled by micro-nano structures so that internal charges can be effectively separated to improve photoelectric conversion efficiency.Cu?OH?₂ nanowire arrays were prepared by a simple and efficient anodic oxidation method and then converted into CuO nanowire arrays by air thermal oxidation.The nucleation and growth process of Cu?OH?₂ nanowire arrays is a typical LaMer Burst model.The density,length and width of CuO nanowires are controlled by changing the anodization parameters and the ratio of anodizing electrolyte.The preparation and control method can effectively improve the charge separation and transmission capability of CuO nanowires,and has higher photoelectrochemical properties,namely,the internal quantum efficiency of CuO nanowires is higher than 57.0%?455nm?in the presence of sacrificial agents.2.Cu?OH?₂ prepared by the electrochemical anodic oxidation method is calcined in N₂ to form a Cu₂O nanowire array,and then different electrochemical deposition TiO2 is adopted on the Cu₂O nanowire array to form a Cu₂O/TiO₂ heterojunction.The structure of nanowires can overcome the defects of short carrier diffusion distance and long light absorption path of Cu₂O itself.At the same time,TiO₂ is successfully electrodeposited in electrolyte containing near neutral titanium source for the first time,reducing the corrosion of nanowire morphology and forming good Cu₂O/TiO₂ heterojunction.Photoelectric test results show that the initial potential and stability of the Cu₂O/TiO₂ photocathode are obviously improved.3.The Cu₂O nanowires array prepared above was used as the substrate,and then TiO₂was deposited on Cu₂O by different physical deposition methods to form a Cu₂O/TiO₂heterojunction.Further photoelectric catalytic test showed that in situ deposition of TiO₂,whether as heterojunction or protective layer,the initial potential and stability of the photoelectric performance were significantly improved.