Synthesis Of BiVO₄-based Photoanode Materials And Research On Their Photoelectrochemical Water Splitting Performances

Bismuth vanadate?BiVO₄?,as a semiconductor photocatalyst,with its suitable band gap,conduction band,valence band position and good chemical stability,is widely used in the fields of photocatalysis and photoelectrocatalysis.However,BiVO₄ has a limited optical activity due to its low photo-generated charge transfer efficiency and high photo-generated electron-hole recombination rate.Therefore,in this paper,we studied about the improvemnet of the defects of BiVO₄ photoanode materials.The g-C₃N₄/Mo:BiVO₄ and NiOOH/PANI/BiVO₄ photoanode materials were prepared on the FTO substrate,which enhanced the photoelectrochemical?PEC?water splitting performance of BiVO₄.The main contents are as follows:?1?g-C₃N₄ was successfully loaded on the surface of Mo:BiVO₄ to structure an integrated CMB photoanode via a facile impregnation method.The remarkable water oxidation photocurrent of CMB photoanode achieved 3.11 mA cm^-2 at 1.23 V vs.RHE under AM 1.5G solar light irradiation,the maximal incident photon-to-current conversion efficiency?IPCE?achieved 45.5%at 430 nm and the maximal applied bias photo-to-current efficiency?ABPE?reached 0.74%at 0.80 V vs.RHE.Moreover,the photocurrent of the CMB photoanode only decreased slightly by 0.18 mA cm^-22 after 1hour of continuous water splitting,confirming the great stability of CMB photoanode.These enhanced PEC water splitting performances were mainly attributable to the Mo doping increased the carrier concentration of BiVO₄ and improved the electron-hole separation efficiency.On the other hand,the formation of g-C₃N₄/Mo:BiVO₄heterojunction accelerated the separation of electrons and holes and effectively inhibited the recombination of carriers.The photoanode materials designed in this work would have a high application prospect for the design and development of new type of photoanode in the future.?2?Polyaniline?PANI?hole-transporting layer was successfully inlaid between the BiVO₄ core and the NiOOH shell to structure an integrated NPB photoanode via a facile photoelectrodeposition method.The remarkable water oxidation photocurrent of NPB photoanode achieved 3.31 mA cm^-2 at 1.23 V vs.RHE under AM 1.5G solar light irradiation,which was greatly increased compared with that of pristine BiVO₄(0.89mA cm^-2 under the same condition).The maximal IPCE achieved 83.3%at 430 nm at1.23 V vs.RHE and the maximal ABPE reached 1.20%at 0.68 V vs.RHE,which were nearly five and ten times higher than that of pristine BiVO₄ photoanode,respectively.This NPB photoanode exhibited excellent stability with about 97.22%Faraday efficiency after PEC water splitting for 3 h.The exciting results demonstrated that PANI showed great potential as a hole-transporting layer for photoanode and NPB was an efficient and stable photoanode material with a great potential application in PEC water splitting.Overall,this work provided an excellent reference on designing and fabricating photoanode materials for the future.