Study On The Fabrication Of Cuprous Oxide And Bismuth Vanadate Based Photoelelctrodes And Their Photoelectrochemical Properties For Water Splitting

With the rapid development of industrialization and population,human beings are facing the severe crisis of energy shortage and environmental deterioration.As a new energy,solar energy is clean,efficient and renewable.The photoelectrochemical technique can make full use of solar energy,however,the suitable semiconductor materials play an important role in the photoelectrochemistry.Among them,transition metal oxides based semiconductors are more common,such as Cu₂O and BiVO₄.As one of the most important photocathode materials,cuprous oxide?Cu₂O?has attracted much attention in photoelectrochemical?PEC?water splitting due to its advantages of suitable bandgap,well photoresponse and low cost.However,the practical application of Cu₂O photocathodes is confined by its poor stability due to its self-photocorrosion in electrolyte solutions.This paper adopted modification methods to enhance photostability and PEC performance of Cu₂O photocathodes.In addition,the porous BiVO₄ photoanode was also prepared.Finally,in order to improve the photoconversion efficiency,a tandem PEC device was designed using Cu₂O as photocathodes and BiVO₄ as photoanodes.The specific research work is as follows:?1?The Cu₂O nanowires?NWs?photocathode was prepared in situ by chemical bath deposition.The experimental results show that when the calcination temperature is 600? and the calcination time is 4 h,the photocurrent density of the prepared Cu/Cu₂O NWs photocathode is the highest,generating a photocurrent density of4.02mA/cm²at a potential of 0 V versus the reversible hydrogen electrode?RHE?under AM 1.5 illumination.?2?Cu₂O/Au,Cu₂O/Ti₃C₂T_x and Cu₂O/H-Ti₃C₂T_x composite photocathodes were prepared by modifying Au nanoparticles?NPs?,thin Ti₃C₂T_x flakes and hydrogen reduced thin Ti₃C₂T_x flakes?denoted as H-Ti₃C₂T_X?on Cu₂O NWs.Compared to the bare Cu₂O photocathodes,the photocurrent densities of Cu₂O/Au,Cu₂O/Ti₃C₂T_X and Cu₂O/H-Ti₃C₂T_X composite photocathodes were increased by 1.07,1.11 and 1.35times,respectively,and the stability of the composite photocathodes was also greatly improved.In addition,systematical characterizations of bare Cu₂O and its composite photocathodes,including XRD,SEM,TEM,XPS,etc.,were performed.?3?Nanporous BiVO₄ photoanodes were prepared on FTO conductive glass by electrochemical deposition.When the electrodeposition time was 5 min,the calcination temperature was 450?,and the calcination time was 2 h,the PEC performance of nanoporous BiVO₄ photoanode is the best.The highest photocurrent density can reach 1.73 mA/cm² at a bias potential of 1.23 V versus the RHE under AM 1.5 illumination.The BiVO₄ photoanode is also fully characterized.?4?A tantem PEC device was designed with the BiVO₄ as photoanode,Cu₂O or Cu₂O/H-Ti₃C₂T_X as photocathode,respectively,and the photoconversion efficiency was also investigated.