Study On Photoelectrochemical Water Splitting Performance Of Molecular Co-catalyst Coupled With Bismuth Vanadate Composite Photoanode

With the speedy development of industries and the elevation of quality for people’s life,it leads to an increasing demand for energy and a promotional awareness for environmental protection.These factors have prompted us to accelerate the process of developing clean and renewable energy.In production and life,many pollution-free energy sources have been used and they have shown advantages over fossil fuels.At present,photoelectrochemical water splitting technology is the brightest method,providing pathway for hydrogen and oxygen production,which uses semiconductor electrodes to convert solar energy into green energy resource.Among them,the oxygen production process of photoanode is the bottleneck in the scientific research of photoelectrochemical water splitting.In recent years,various of semiconductors have been extensively researched in photoelectrochemical water splitting,including TiO₂,Bi VO4,Fe2O3,WO3 and Ta3N5.However,they also have many inherent problems such as serious photocorrosion,fast recombination of photogenerated holes and electrons,slow surface and interface catalytic reactions,and inferior materials’efficiency and stability.In this thesis,the photoanode based on Bi VO₄ is taken as the research object,and some simple modification strategies are adopted to prepare composite photoanode.The water splitting performance of the as-prepared photoanodes are investigated and the specific contents are as follows:1.The nanoporous bismuth vanadate was prepared by electrodeposition of BiOI and calcination.Then,a simple impregnation with polyoxometalate solution strategy was adopted to prepare composite photoanode.The Ni₃POM/Fe OOH/Bi VO₄ composite photoelectrode could provide current value of 5.2 m A/cm~2 at 1.23 V vs.RHE.In this system,polyoxometalates and iron oxyhydroxide synergistically improve the photoelectrochemical performance of bismuth vanadate photoanode,in which Fe OOH is the main substance to improve the photoelectrochemical water oxidation activity,and polyoxometalate is the main part to improve the stability of photoanode materials.2.By preparing graphene oxide and synthesizing the molecular metal copper porphyrin,we effectively constructed the Cu TCPP/GO/Bi VO₄ composite photoanode by impregnation method.In the experimental study,we found that the photocurrent density of the Cu TCPP/GO/Bi VO₄ composite photoanode could up to 5.0 m A/cm~2（1.23V vs.RHE）,which is about four times that of the blank bismuth vanadate photoanode.We also used SEM,TEM and XPS physical characterization methods to analyze the experimental data.It is confirmed that Cu TCPP as a molecular catalyst provides more active sites in the system.At the same time,GO and Cu TCPP could form a strong conjugation effect system,effectively inhibiting the recombination of photogenerated electrons and holes,so the composite materials performed good water oxidation activity in photoelectrocatalytic water splitting.