Photoelectrocatalytic Characteristic And Preparation Of Nanoporous WO₃/W Thin Film

WO3is one kind of narrow band semiconductor (2.5-3.0eV) and hasa good response to the visible light of400-500nm. It has received muchresearch and attention due to the excellent photocatalytic activity. Anodicoxidation method is a simple, fast, and easy-to-control way to prepare thenanometer materials. Compared to the conventional technology, thenanoporous WO3/W thin film prepared by Anodic oxidation method hasa natural combination between the tungsten and thin film layer whichmake the WO3/W nanoporous thin film show good optoelectronictransmission performance. This thesis studied the preparation ognanoporous WO3/W thin film by anodization and tested thephotoelectrochemical performance. In order to improve the performanceof nanoporous WO3/W thin film, nanoporous WO3/W photoanodemodified with cobalt–phosphate (Co–Pi) catalyst was synthesized in thisstudy.In this thesis, we studied the main factors influencing thenanoporous WO3/W thin film in the process. Through the ScanningElectron Microscope (SEM) and Linear volt-ampere scanning curve (I-V),we found that the main factors include the electrolyte composition,anodizing voltage, anodizing time. The conditions for preparingnanoporous WO3/W thin film in aqueous solution are: electrolytecomposition of0.3wt%NaF,0.3%HF, anodizing voltage of60V, anodicoxidation time of60min. The pore diameter of nanoporous WO3/W thin film was at50-100nm with uniform distribution and well-definedstructure. When the applied voltage reaches1.0V, the photocurrent wasup to2.4mA, which indicated that nanoporous WO3/W thin film exhibitsexcellent catalytic performance.Herein, we present a photo-assisted electrodeposition of Co–Picatalyst on nanoporous WO3/W thin film for photoelectrochemical watersplitting and characterized the Co-Pi/WO3by linear sweep voltammetrycurves (I-V), light conversion efficiency, stability, UV-visible diffusereflectance spectroscopy (UV-vis) and X-ray photoelectron spectroscopy(XPS). The photocurrent density of Co-Pi/WO3was much higher thansingle nanoporous WO3/W. The light conversion efficiency of Co-Pi/WO3increased by15%compared with the nanoporous WO3/W thin film.Through the current-time curve, we found that Co-Pi/WO3was morestable than single nanoporous WO3/W thin film.