Preparation And Photo(-electro)catalytic Water Snlitting Study Of Perovskite Oxynitrides

Nowadays,photocatalytic water splitting under solar irradiation have attracted lots of attention due to the low energy cost,recyclability,and environmental friendliness.It is considered to be one of the most effective ways to solve energy shortage and environmental pollution.In the field of solar utilization and conversion,traditional oxide semiconductors have low theoretical solar-to-hydrogen?STH?efficiency due to the large band gap,which limits the application in the field of photocatalytic water splitting.Perovskite-type oxynitrides have adjustable structure,narrower bandgap,and suitable band-edge position for water splitting,and thus show a great potential in photo?-electro?catalytic water splitting.This paper focuses on the preparation of perovskite-type oxynitrides with high crystallinity.Their photocatalytic or photoelectrocatalytic performance for water splitting were also studied.The main work is as follows:1.The perovskite SrNbO₂N photoanode with high photocurrent was prepared by flux-assisted nitridation.Inert atmosphere?Ar?was used to suppress the formation of surface anion defects.Meanwhile,Co3O4 nanoparticles were deposited on the photoanode to as cocatalyst to improve the efficiency of photo-generated carriers.The effects of nitridation temperature,molten salt composition and annealing process on crystallinity,photoelectric properties and surface defects were studied.XPS was applied to analyze the surface anion defects and explain the reason for the improved photoelectrochemical activities.2.We prepared LaTaON₂ by nitridation of oxide precursor obtained by a polymerizable complex method.The effect of different cocatalysts?Fy-NiOx and Co3O4?and thickness of photoanode on the photocurrent enhancement of LaTaON₂ photoanode was investigated.It is pointed out that the Co₃O₄ as cocatalyst and the relatively thin thickness of photoanode play an important role in the carrier separation of LaTaON₂photoanode.In the suspension photocatalytic system,the stability of hydrogen production was improved in the argon atmosphere.Then,XPS was carried out to explain the instability of the photocatalytic performance of oxynitrides.