Preparation And Properties Of Cu₂O-based Composite Photocatalysts By Soft Template Method

Cu₂O is widely used in hydrogenation of water and photodegradation of organic pollutants due to its green environment,cheap availability and visible light response.However,Cu₂O has defects such as small specific surface area and low quantum efficiency,which severely limits its photocatalytic activity.Cu₂O complex photocatalyst was prepared by soft template method to improve its morphology and structure,and graphite phase carbon nitride（g-C₃N₄）and AgBr were further introduced to optimize its band structure and increase its quantum efficiency.The composition,morphology,optical properties and photocatalytic degradation of organic dyes were studied.Cu₂O photocatalysts were prepared using a soft template system of ethanol/ethylene glycol/CTAB/coconut oil acylcreatine sodium.The effect of amount of sodium creatine in coconut oil,viscosity of solution medium and reaction time on the preparation of Cu₂O by soft template method was investigated.A single-factor comparison experiment determined that Cu₂O,prepared with 1m L coconut oil acylcreatine sodium,ethylene glycol as solvent,and 25 min reaction time,was a hollow porous microsphere with a large specific surface area(33.34m²g^-1)and a high electron cavity separation efficiency.Catalytic degradation of methyl orange by 60min of light resulted in a degradation rate of 81%,51.3 times higher than the formless preparation of Cu₂O.However,there was no significant degradation effect on Rhodamine B,indicating that Cu₂O photocatalyst was different for different dyes.The g-C₃N₄/Cu₂O composite photocatalyst was prepared by soft template method by adding g-C₃N₄synthesized by supramolecular polymerization to the precursor solution of Cu₂O.The effect of g-C₃N₄dosage on g-C₃N₄/Cu₂O composites was investigated.The results showed that the Cu₂O microspheres of g-C₃N₄/Cu₂O composite photocatalyst were observed on and between the layers of g-C₃N₄in SEM images.Compared with Cu₂O prepared by soft template method,the average particle size is reduced from 1.53μm to 0.52μm,and the specific surface area is reduced from33.34 m²g^-1increased to 45.1 m²g^-1;photoluminescence spectra（PL）indicated that the separation efficiency of photogenerated electrons and holes increased.When the amount of g-C₃N₄was 150 mg,the photocatalytic degradation of MO was the best,and the MO solution was decolorized by 91.2%within 60 min.After 5 cycles,g-C₃N₄/Cu₂O had a degradation rate of 80%.AgBr/Cu₂O composite semiconductor photocatalyst was prepared by chemical deposition method.The effect of AgNO₃dosage on photocatalytic activity was investigated.The analysis results show that Ag in the AgBr/Cu₂O composite material is mixed with Ag⁺and Ag⁰,the light absorption wavelength is red-shifted from 610nm to 640 nm,and the PL spectrum shows that the photogenerated electron-hole recombination rate decreases.When the dosage of AgNO₃is 4%,the photocatalytic activity of AgBr/Cu₂O is the best,and the decolorization of MO is 96.4%after 60 min of illumination;the AgBr/Cu₂O composite has good stability,and the AgBr/Cu₂O composite still maintains 89%degradation rate after 5 cycles.