Study On Optimization Of Z-Scheme Catalyst La₂O₃/ZnIn₂S₄/RGO/BiVO₄ And Its Performance Of Photocatalytic Hydrogen Production

With the development of social economy,energy and environmental issues have become increasingly prominent.Therefore,the development of new clean renewable energy is becoming increasingl y urgent.In recent years,photocatalytic hydrogen production technology has received the close attention by the majority of researchers,and it is one of the most promising methods to solve these problems effectively.How to produce highly efficient,strong visible light absorption and good stability of the photocatalyst has become the key to the use of solar photocatalytic decomposition of water for hydrogen production.In recent years,Z-Scheme catalyst is a new type of composite photocatalyst has been developed rapidly,Z-Scheme catalyst has the advantages of high utilization efficiency of visible light,good stability of catalyst and so on.This article studies on the optimization of Z-Scheme catalyst La2O3/Zn In2S4/RGO/Bi VO4 has been constructed based on the previous research results of the group,and study its performance of photocatalytic hydrogen production and degradation of pollutants.The morphology of Bi VO4 in the Z-Scheme catalyst was optimized.The Bi VO4 catalyst of different morphologies were synthesized by hydrothermal method and the corresponding Z-Scheme catalysts were synthesized,characterized by various analytical techniques,such as XRD,SEM,BET,Raman,UV-vis and so on.The results show that the morphology of Bi VO4 has a significant influence on the graphene loading,and the specific surface area and the total pore volume of the Z-Scheme catalyst.In the prepared of six morphologies,the acicular Bi VO4 has the best effect on the graphene loading,and the prepared Z catalyst has the largest specific surface area.The photocatalytic hydrogen production rate of Z-Scheme catalyst prepared by Bi VO4 of aciclar was the maximum,which was 563.3 μmol/(g·h).Optimization of the electron mediated graphene with different loadings and the types of oxidation/reduction cocatalyst in the Z-Scheme catalyst.The catalysts with different graphite content were prepared by evaporation and photo reduction method.The catalyst were characterized by various analytical techniques,such as XRD,SEM,Raman,BET,PL,UV-vis and so on.With the increase of graphene loading,the specific surface area and total pore volume of Z-Scheme catalysts increased firstly and then decreas ed,and the Bi VO4 crystal was affected by the graphene loading.The photocatalytic activity of the experimental results show that the photocatalytic hydrogen production rate increased firstly and then decreased with the increase of the graphene loading.When the graphene loading is 2.0wt%,the photocatalytic activity was the highest,which was 649.4 μmol/(g·h).The oxidation cocatalyst are loaded on the Bi VO4 surface by impregnation calcination method.The reduction cocatalyst are loaded on the Z-Scheme catalyst for light deposition method.The experimental results show that the activity order of the oxidation cocatalyst is Ni O > Ru O2 > Mn O2 > Ir O2 > Cu O > Co O,and the activity sequence of the reduction cocatalyst is Pt > Pd > Au > Ag.When the oxidation cocatalyst is Ni O,the reduction cocatalyst is Pt,the hydrogen production rate is the maximum,whi ch is 726.3 μmol/(g·h).The performance of the best Z-Scheme catalyst had been studied for photocatalytic hydrogen production from degradation pollutants.The photocatalytic hydrogen production rate reached a maximum when the formaldehyde as organic pollutants,and its concentration of 1 mol/L,the catalyst dosage of 1.5 g/L and the p H value of solution is 13,which is 1804.1μmol/(g·h).The trend of formaldehyde degradation after photocatalytic of 3 h was basically consistent with the trend of photocatalytic hydrogen production rate.When the formaldehyde concentration is 1 mol/L,the formaldehyde degradation amount reached the maximum is 86.0 mmol/g.The hydrogen production rate can be increased 15% compared to the air condition by increasing the oxygen concentration in the reaction system,which is 2066.6 μmol/(g·h).The photocatalytic stability of Z-Scheme catalyst was good.The Z-Scheme after optimization has been improved 70% compared to the previous,and have a high level in the study of Z-Scheme photocatalytic hydrogen production under visible light in has been reported works.