Study On The Photocatalytic Activity Of Cu₂O Composites And Its Photo-corrosion Resistance

At present,antibiotic wastewater is one of the important water pollutants,which has the characteristics of wide pollution range and high biological toxicity.The problem of antibiotic wastewater pollution control is imminent.As an environmentally friendly water treatment technology,photocatalysis has attracted extensive attention.The stability of photocatalysts is one of the factors to the application research of photocatalysis technology.Among many photocatalysts,copper oxide（Cu₂O）has been paid attention to in the field of photocatalysis due to its narrow band gap and ability to be excited under visible light.However,due to the shortcomings of low-valent metal oxides that are easily oxidized and corroded,their application in practical processes is limited.Therefore,study how to improve the stability of photocatalysts is very important.In this paper,the liquid phase reduction method was used to prepare Cu₂O,and its photocatalytic performance and stability were studied.From two ways of constructing heterojunction materials and composite electron transport conductor materials,Combined Cu₂O with Ti O₂,polypyrrole（PPy）and graphene oxide（GO）.the photocatalytic performance and stability of Cu₂O was studied by simulating antibiotic wastewater.In this paper,X-ray diffraction（XRD）,Scanning electron microscope（SEM）,Ultraviolet-visible diffuse reflectance analysis（UV-vis）,Photoluminescence Spectroscopy（PL）analysis,electrochemical impedance spectroscopy（EIS）analysis and other characterization methods were used to study the Elemental composition,chemical form and morphological particle size,and the photo-catalytic degradation of tetracycline hydrochloride was studied to study its cycle stability.The specific research content is as follows:（1）Cu₂O powder was prepared by liquid phase reduction method and used for photocatalytic degradation of tetracycline hydrochloride to investigate its photocatalytic performance and stability.The results show that when Cu₂O is used alone as a photocatalyst,it has a better treatment effect on 50 mg/L tetracycline hydrochloride,but the copper dissolution is higher,the stability is poor and causing secondary pollution.The main active species is·O₂^-.（2）A series of Cu₂O/TiO₂ heterojunctions with different ratios were prepared by the liquid phase reduction method.The composite materials can accelerate the transfer of electrons,inhibit the recombination of photo-generated electron holes,and significantly improve the photocatalysis and photo-corrosion resistance of Cu₂O.The degradation efficiency of tetracycline hydrochloride was increased to 96.93%,and the dissolution of copper was significantly suppressed;PL spectra and EIS analysis were performed to further explain that the constructed heterojunction promotes the electron transfer process,avoids the recombination of electrons and holes,and the accumulation of electrons,and reduces photo-corrosion induced by electrons and holes.Also explored the mechanism of photocatalytic reaction.（3）The chemical polymerization method was used to synthesize PPy powder.PPy/Cu₂O and GO/Cu₂O composite materials were prepared by adding proper amount of electron transfer conductors PPy and GO during the preparation of Cu₂O.The results show that when the amount of PPy is 5%and the amount of GO is 0.4%,the removal rate of tetracycline hydrochloride is highest,and reduced the dissolution of copper;with the increase of p H,the ability of photocatalytic degradation of tetracycline hydrochloride was enhanced.The kinetic analysis of the reaction process,the correlation coefficients are all higher than 0.9,complying with the first-order reaction kinetic equation,and exploring the reaction mechanism,it is confirmed that superoxide radicals play a major role in the photocatalytic degradation of tetracycline hydrochloride.