Preparation And Photoelectrochemical Properties Of Oxide Photoelectrodes

In the past,for the sustainable development of the Earth,a large amount of research has been conducted on the utilization of renewable energy and the development of clean and green energy.So far,we have preliminarily studied several strategies for utilizing renewable energy,and photoelectrochemical（PEC）water decomposition is one of them.It has good development prospects and is both a new opportunity and a new challenge in the future world development process.With the continuous development of society and economy,the PEC water decomposition technology has received more and more attention,and a large amount of research has been conducted to achieve high solar hydrogen production efficiency.In order to meet the efficiency of industrial hydrogen production and increase the competitive advantage with other hydrogen production methods in commerce,solving the performance of semiconductor materials is the most critical challenge.The selection of semiconductor materials directly affects the yield of hydrogen evolution from PEC decomposition water.It is necessary to choose semiconductor materials that increase the separation of photo generated charge carriers（electron holes）,reduce the recombination between photo generated charge carriers（electron holes）,and improve the survival time of charge carriers;We also need to choose semiconductor materials with suitable bandgaps to facilitate the redox reaction of water decomposition;In addition,stable photo electrodes with high resistance to photo corrosion should also be selected.Of course,in addition to meeting the physical characteristics of semiconductors mentioned above,developing economical and practical semiconductor materials is an important prerequisite for achieving PEC water decomposition.In recent years,considerable progress has been made in PEC systems by improving the light absorption and charge separation/transfer of PEC semiconductor materials,and the construction of heterojunctions in semiconductor photoanodes has been shown to be an effective strategy for significantly improving solar-fuel conversion efficiency.This article improves the existing photoanode material by loading a passivation layer and constructing a heterojunction to enhance the PEC performance of the original photoelectrode.We studied iron oxide（Fe₂O₃）and zinc oxide（ZnO）with excellent PEC water decomposition performance,tested the phase and band structure of the samples,optimized the preparation of the samples,and modified the electrode surface to improve the electron transfer characteristics of the working electrode and the PEC performance of the photoanode.Finally,we analyzed the charge transfer mechanism of PEC water decomposition at the working electrode.Based on the characteristics of the sample itself,heterojunctions and loaded co catalysts are constructed using the characteristics of semiconductors,significantly improving the efficiency of incident monochromatic photon electron conversion.The specific research content is as follows:1.Fe₂O₃/MoO₃ nanorods photoanode was prepared.In this paper,the composite photoanode of Fe₂O₃/MoO₃ nanorods was prepared by hydrothermal method and impregnation method,and the PEC performance was analyzed by different calcination temperature.The photocurrent density of Fe₂O₃/MoO₃-350 working electrode reaches 0.81 m A·cm^-2,which is 3.2 times of that of Fe₂O₃ working electrode.MoO₃ passivation layer can effectively inhibit photogenerated carrier recombination.The incident photoconversion efficiency（IPCE）of Fe₂O₃/MoO₃-350 photoanode at 365 nm is 33.97%,which is 3 times higher than that of Fe₂O₃ photoanode.The main purpose of our research is to provide an effective strategy for solar energy conversion to prepare efficient PEC photoanode materials.2.ZnO/Co₃O₄ has p-n heterojunction photoanode.ZnO/Co₃O₄ heterojunction photoanodes with p-n type structure were synthesized by hydrothermal method,electrophoretic deposition and impregnation.By changing the impregnation time,the Co₃O₄ loading capacity in ZnO/Co₃O₄photoanode was controlled,and the PEC performance of composite samples with different Co₃O₄loading capacities was analyzed.The results show that the carrier transport capacity of ZnO/Co₃O₄ is obviously enhanced.The photocurrent density of ZnO/Co₃O₄-10 photoanode is 2.4 times that of pure ZnO photoanode.At 420 nm,the IPCE of ZnO/Co₃O₄-10 photoanode is 1.9 times that of pure ZnO photoanode.