Fabrication And Structure Regulation Of One-dimensional WO₃ Photo-anodes And Their Photoelectrocatalysis Performance

Photoelectrocatalysis water splitting?PEC?is considered to be one of themost promising sustainable methods for obtaining and storing solar energy to fuel.Tungsten trioxide?WO₃?has the advantages of good electron transport characteristics,abundant raw material reserves,and environmental friendliness.Compared with other semiconductor materials,the carrier diffusion distance of WO₃ is moderate??150 nm?,which can ensure a higher carrier separation efficiency,the lower valence band position of WO₃ also makes it suitable for oxygen evolution reaction.Meanwhile,One-dimensional?1D?nanomaterials facilitate the transport and separation of carriers,which makes the application of such morphologies to PEC applications a major concern.This work is carried out on the topic of the preparation of novel andefficient one-dimensional WO₃ photocatalytic photo-anode.The main experimental method is to prepare photo-anode by directly fabricating one-dimensional nanostructured WO₃ on the surface of Transparent conductive oxide?FTO?by electrospinning.Then through element doping,structure regulation and the construction of semiconductor heterostructure to achieve joint enhancement of PEC performance.?1?Using WCl₆ and FeCl₃·6H₂O as raw materials,by adjusting the ratioof WCl₆ and FeCl₃·6H₂O,WO₃ nanofibers with different Fe doping concentrations were prepared by electrospinning.Photoelectrocatalytic studies have shown that Fe doping can increase the absorption of visible light of WO₃,and the lower doping concentration facilitates the separation of carriers.Further more,WO₃ nanofiber photoanode with 0.32 at.%Fe doping concentration has the best photoelectrocatalytic performance of 34.3?A·cm^-2 at the bias of 1.23 V?vs.Ag/AgCl?.?2?By adjusting the ratio of different amounts of Polyvinylpyrrolidone?PVP?and Tea saponin,the controllable preparation of one-dimensional WO₃meaoporous nanobelts was achieved.Studies have shown that the incorporation of tea saponin as a foaming agent into the raw material enables in-situ pore formation on the surface and inside of the fiber,which in turn enables controlled preparation of fully mesoporous WO₃ nanobelts.Photoelectrocatalytic studies have shown that the photocurrent density of mesoporous WO₃ nanobelt photoanodes can reach 311?A·cm^-2?1.2 V vs.Ag/AgCl?,which is 2.3 times that of cylindrical nanofibers.The enhanced PEC performance can be mainly attributed to the enhanced charge transport and enhanced light absorption of mesoporous structures.?3?One-dimensional WO₃ nanofiber photoanode was soaked in N,N dimethylformamide?DMF?with equimolar ratio of bismuth nitrate pentahydrate?Bi?NO₃?₃·5H₂O?and vanadyl acetylacetonate?VO?acac?₂?,Annealing was performed to achieve 1D-WO₃/BiVO₄ core-shell heterojunction photo-anode.Photoelectrocatalytic studies have shown that the designed 1D-WO₃/BiVO₄heterojunction photoanode shows a maximum photocurrent density of 2.8mA·cm^-2 at 1.23 V vs.RHE,which is about 20 times that of the 1D-WO₃photoanode(0.15 mA·cm^-2),which is comparable to the best performance reported in the WO₃/BiVO₄ composite photoanode.The enhanced PEC activity is mainly attributed to the construction of WO₃/BiVO₄ heterojunctions,which can promote the separation and transfer of photogenerated carriers,thereby improving PEC performance.