Preparation And Properties Of Visible Light Response Of Cu₂O/ZnO Catalyst

Zinc oxide（ZnO）, an intrinsic n-type semiconductor with a direct band gap of 3.37 e V, is considered to be a promising partner with Cu₂ O. Cuprous oxide（Cu₂O）, with a direct band gap of 2.1e V, is a natural p-type semiconductor owning a high absorption coefficient in the visible light region, and theoretical photoelectric conversion efficiency is 20%. Cu₂O/ZnO has shown great potential in photovoltaic, photocatalysis, and photochemical catalysis applications due to the low-cost, nontoxicity,abundance and variety of preparation methods. Cu₂O/ZnO semiconductor has broad application prospects in the light catalysis. In this paper, methyl orange was using as pollutant and composite catalyst Cu₂O/ZnO responding to visible was constructed for degradation of methyl orange dye wastewater via Cu₂ O, ZnO physical binding. The prepared Cu₂O/ZnO samples were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, UV–vis diffuse reflectance spectrometer energy-dispersive spectrometer, X-ray photoelectron spectroscopy（XPS） and photochemical reaction instrument to analyses the physical structure and photocatalytic properties. The results show:1 Hydrazine hydrate as reductan preparing Cu₂O/ZnO by chemical bath precipitation method（1） Cu₂ O is nanoparticle and ZnO is nanoparticle. Cu₂O/ZnO catalyst have a strong visible light response properties without other impurities, high degree of crystallinity, responding to visible wavelengths is 640 nm, the band gap is 1.9 e V.（2） By contrast ZnO, Cu₂ O and Cu₂O/ZnO on performance, we can see that as the increases of reaction Cu₂₊ concentration, photocatalytic degradation of MO effect appeared after the first increased to decreased with Cu₂O/ZnO, when concentration of Cu₂₊ is 0.0375 mol/L, Cu₂O/ZnO composite catalyst appeared the best photocatalytic performance.（3） photocatalytic reaction factors showed that the concentration of MO is too large, too heavy and thus affect the color of the solution transmittance, with an initial concentration from 50 mg/L to 300 mg/L, the degradation rate of light gradually decreases. With increasing amounts of catalyst addition, the effect of light degradation of MO showed an increasing trend. When the catalyst is added in an amount 0.1 g, photocatalytic degradation of 100 mg/L of MO reaction 4 h, with the value of p H 3.8 MO photocatalytic effect amount to 75%.2 Glucose as a reducing agent preparing Cu₂O/ZnO by chemical precipitation water bath（1） Cu₂ O is nanoball and ZnO is nanoparticle. Cu₂O/ZnO catalyst have a strong visible light response properties without other impurities, high degree of crystallinity, responding to visible wavelengths is 680 nm, the band gap is 1.82 e V.（2） By contrast ZnO, Cu₂ O and Cu₂O/ZnO on performance, we can see that as the increases of reaction Cu₂₊ concentration, photocatalytic degradation of MO effect appeared after the first increased to decreased with Cu₂O/ZnO, when concentration of Cu₂₊ is 0.056 mol/L, Cu₂O/ZnO composite catalyst appeared the best photocatalytic performance.（3） photocatalytic reaction factors showed that the concentration of MO is too large, too heavy and thus affect the color of the solution transmittance, with an initial concentration from 50 mg/L to 300 mg/L, the degradation rate of light gradually decreases. With increasing amounts of catalyst addition, the effect of light degradation of MO showed an increasing trend. When the catalyst is added in an amount 0.1 g, photocatalytic degradation of 100 mg/L of MO reaction 4 h, with the value of p H 3.8 MO photocatalytic effect amount to 98%.3 Cu₂O/ZnO catalytic mechanism study showed that photo-generated holes and ·OH radical is the main active substance.