Studies On The Performance And Mechanism Of Bismuth Vanadate Photoanode For Photoelectrochemical Water Splitting

As the development of photoanode material,bismuth vanadate?BiVO₄?is expected to be a plausible avenue for achieving highly efficient solar-assisted water splitting.At the same time,it also has some problems such as serious carrier recombination,slow oxygen evolution kinetics,and insufficient optical utilization.Here,we have implemented a series of strategies such as hole transporting adjustment,noble metal modification,heavy metal doping,and oxygen evolution additives to overcome the drawbacks,which significantly improves the hydrolytic activitive performance of BiVO₄-based photoanode materials.The research including:1.An ultra-thin g-C₃N₄,inserted between the oxygen evolution co-catalyst?OEC?and nano-BiVO₄electrode can improve the photoelectr-ochemical?PEC?performance.in turn,the photoanode can suppress carrier recombination for the hole transport performance of ultra-thin g-C₃N₄.A photocurrent density and the applied bias photoelectric conversion efficiency?ABPE?at lower bias voltages of 4.20 m A cm^-2?1.23 Vvs.RHE?and 1.65%?0.62 e V?is achieved by the CoOOH/g-C₃N₄/BiVO₄ photoanode,which were 4.29 and 10.31 times of BiVO₄(0.98 m A cm^-2 and 0.16%).It is found that the intrinsic ultra-thin g-C₃N₄ can boost hole extraction from BiVO₄and prolong holes trapping lifetime on BiVO₄surface.This work suggests a promising nexus between semiconductors and electrocatalyst.2.The photoreduction method was used to construct a CoOOH/Ag/BiVO₄photoanode.In this section,Ag nanoparticles are uniformly dispersed on the surface of BiVO₄,which would form the surface plasmon resonance effect?LSPR?,increasing the light absorption and hole transport efficiency of the substrate BiVO₄.CoOOH nanoparticles as an OEC can effectively increase the reactive sites for surface O₂ produce,and accelerate the generation of O₂.As the result,the photocurrent density and the ABPE of 3.28 m A cm^-2 and 0.82%were achieved by the CoOOH/Ag/BiVO₄ photoanode,which were much larger than BiVO₄.3.We herein demonstrate the electronic energy level adjustment via molybdenum?Mo?doping significantly increase the carrier concentration of CoOOH/Ag/BiVO₄PEC cells.Under multiple control,the water oxidation photocurrent and the relatively low bias ABPE of CoOOH/Ag/Mo:BiVO₄ reached impressive values:4.02 m A cm^-2?1.23 Vvs.RHE?and 1.12%?0.74 e V?,which is 4.27 times and 7.47 times higher than BiVO₄(0.94 m A cm^-2,0.15%).This work sheds light on the design of BiVO₄ based devices for application in solar to fuel conversion.