Interface Engineering On B_iVO₄ Based Photoanodes For Photoelectrochemical Water Splitting

Hydrogen has a series of advantages,such as high energy density,storage and mobility,easy reformation and conversion,combustion without pollution.It is considered as an ideal carrier of green energy,which can solve the increasingly serious energy crisis and environmental pollution of human society.Based on the strategic significance of energy development,China has included the hydrogen industry into the key development plan since the 13th five year plan,and written it into the government work report in 2019.A series of hydrogen industry bases have emerged one after another,and the industrial chain and market benefits have gradually emerged.In the current hydrogen production technology,the photo-electrochemical?PEC?cell water splitting technology generates high-purity hydrogen through a renewable solar-driven hydrolysis reaction,which is a safe,green,and sustainable process.However,the efficiency of PEC water splitting is still handled at a low level,which seriously restricts the industrialization process.water oxidation dominated by hole carriers excited in the photoanode is a critical bottleneck that hampers PEC overall efficiency due to sluggish hole transfers and surface reaction kinetics for most semiconductors.N-type bismuth vanadate?BiVO₄,BVO?semiconductor emerging as a promising photoanode material,has been attracting considerable attention owing to its suitable energy band structure with dual licenses for visible light harvesting and water splitting.Up to now,three-dimensional?3D?porous BVO can indeed minimize bulk charge recombination to yield high separation efficiency,unfortunately,although hot carriers have the opportunity to separate and migrate to the solid/liquid interface,the sluggish interface reaction dynamics still limit the improvement of the overall efficiency and become a critical step.There fore,in this paper,three-dimensional porous BVO is used as the model photoanode,we focus on implementation of interface reconstruction project and optimize water oxidation reaction?W0R?of solid/liquid interface activity.The aim is to improve the extraction and injection kinetics of hole carriers at the same time,to obtain significantly improved photoelectrochemical water splitting ef ficiency,and provides a useful scheme for the design of high activity photoelectric materials.The details are as follows:1.We introduce p-type Co₃O₄ NPs and amorphous CoFe-LDH NSs over the porous BVO photoanode,dual interface layers including a buried p-n junction layer and catalyst layer to synergistically accelerate hole extraction and W0R.As a result,Compared with the bare BVO photoanode,the resultant CoFe-LDH/Co₃O₄/BVO photoanode yields a near fourfold enhanced photocurrent density of 3.9 mA cm2 at 1.23 VRHE with a cathodic shift of 410 mV at onset potential under AM 1.5G illumination.Furthermore,the decoupled dynamics analysis determines that the designed dual interfaces contribute to both hole extraction efficiency of up to 90%and a surface injection efficiency of up to 71%.T his work introduces a coordinated multi-interface engineering strategy that provides innovative ideas for designing high-efficiency solar fuel PEC cells.2.We herein apply an ionized argon plasma technology on three-dimensional?3D?porous BVO to controllably generate surface local oxygen vacancies,experiments found that these surface oxygen vacancies have very vibrant W0R catalytic activity.Therefore,we propose that directly exploiting the intrinsic catalytic sites on semiconductor surface may be more conducive to the coupling of the photoactivity and surface reactivity of the photoelectrode,which is different from the traditional artificial integration of loading co-catalysts on the photosensitive semiconductor.As a result,An optimized BVO photoanode with surface oxygen vacancies exhibits a remarkable photocurrent density of 4.32 mA cm-2 at 1.23 VRHE under 1 sun illumination?A M 1.5G,100 mW cm-2?,which is over 2-fold higher than that of pristine BVO counterpart,comparable to most of BVO photoanodes with various advanced co-catalysts reported recently.This study provides an solution to address the sluggish catalytic reactivity on most metal oxides,and it can be used as a reference for the design of various solar fuel PEC cells.