Study On Preparation And Photocatalytic Performance Of Several Kinds Of Visible-light Responsive Cu-based Photocatalysts

Photocatalytic technology, a new type of waste water treatment and airpurification technology, has the advantages of efficient, stable and green, and thus haspotential application prospect in control environmental pollution. Compared with titaniumdioxide, cuprous oxide has narrower band gap (~2.0eV), can be excitated by visible light.Since it was reported to be able to split water to generate hydrogen under visible light,Cu2O has been considered having good application prospect in semiconductorphotocatalytic technology, thus caused broad attention of researchers. However, there alsohave many problems in the preparation process of cuprous oxide and its practicalapplication, such as the preparation process is complex and low efficiency and the Cu2Ophotocatalyst is difficult to be separated from the reactants and recycled and also lowefficiency in the application of photocatalytic and so on. This paper is based on thepredecessors’ research, aiming at improving and optimizing the existing shortcomings inthe course of preparation of cuprous oxide. Making the operation more convenient, energyconservation and green. In addtion, in order to facilitate the Cu2O photocatalyst to beseparated from the reactants and recycled and improve its photocatalytic performance, wemodified it using simple and efficient methods by the means of loading or the preparationof heterojunction. The main research contents and results are as follows:1. Preparation of nanocrystalline Cu2O by a modified solid-state reaction methodand its photocatalytic activity. The nanocrystalline Cu2O was successfully prepared bycalcining the precursor synthesized by a ball-milling step using Cu2(OH)2CO3andH2C2O4·2H2O as initial reactants without any other additives. The as-synthesized precursorand the resulting calcined product are characterized by XRD and TG/DTA. The resultshows that the reaction between Cu2(OH)2CO3and H2C2O4·2H2O is complete after15minof milling. The Cu2O is obtained with crystallite sizes of15-21nm after the ball-milledprecursors is calcined at310℃for a certain time. The XRD also shows that theball-milling time and the calcining time influence the crystallite sizes of the products to acertain extent. The average crystallite sizes of Cu2O decreases gradually with the increaseof ball milling time, while they increase gradually with the increase of calcining time. In addition, the prepared Cu2O exhibits a high catalytic activity for the photodegradation ofmethyl orange under visible light irradiation, and the photocatalytic degradation ratio ofmethyl orange reaches to88.7%after2h of irradiation.2. A facile one-pot green synthesis of nano-Cu2O/Ca(OH)2composite by ainterface reduction method. Nano-Cu2O/Ca(OH)2composites are successfullysynthesized via interface reduction method from the reaction mixture of copper chlorideand calcium hydroxide using glucose as reducing agent. The synthesized samples havebeen characterized by X-ray diffraction. The results show that the synthesized samples arecubic nanocrystalline Cu2O/Ca(OH)2composites with a Cu2O crystalline size distributionin a narrow range, and Ca(OH)2powders serve as both reactant for the formation ofCu(OH)2precursors and as carrier controlling the size of the resulting Cu2O crystallines. Inaddition, the effects of reaction temperature, reaction time and copper ion concentration onthe crystallinity and crystal size of Cu2O have been explored as well.3. Preparation of Cu2O/AC photocatalyst and its photocatalytic activity.Cu2O/AC photocatalyst has been succesfully synthesized using a facile one-pot routethrough reflux forced hydrolysis and reduction of solvent method. Activated carbon wasused as the carrier, copper acetate acted as copper source and the mixture of ethyleneglycol and water was used as solvent. The as-prepared samples were characterized by XRDand SEM techniques. The results showed that the Cu2O was at nanoscale and it evenlydispersed on the surface of the carrier. Choose dimethyl phthalate as degradation material,detailed research of the photocatalytic performance of Cu2O/AC has been developed.4. Synthesis of visible light-responsive Cu2O/ZnO nanocomposite via a facileone-pot route. A facile one-pot route for preparing the visible-light-driven Cu2O/ZnOnanocomposites photocatalysis has been developed in our work. The as-synthesizedsamples are characterized by X-ray diffraction (XRD). The results show that their phasecomposition, crystallinity and the crystal size are affected by the reaction temperature, thereaction time and the initial Cu2+concentration. The UV-vis absorption spectroscopymeasurement shows that the optical activity of the as-synthesized Cu2O/ZnOnanocomposite is changed compared with that of pure ZnO, exhibiting enhancedabsorption in the visible light range, which would be hopeful for more practicalapplications in future photocatalysis.5. Preparation of Cu2O/Bi2O3nanocomposite by low-temperature solid-state reaction its photocatalytic activity. Cu2O/Bi2O3nanocomposite with good crystallizationhas been successfully prepared via low-temperature solid-state reaction using CuCl,Bi(NO3)3·5H2O and NaOH as raw materials. The as-prepared products were characterizedby X-ray diffraction(XRD). The results show that the ball milling time andCuCl/Bi(NO3)3·5H2O molar ratio influence the crystallinity and the crystal sizes of theproducts to a certain extent. And, we have found that the formation of Cu2O/Bi2O3nanocomposite is a mutual promotion process. In addition, the prepared Cu2O/Bi2O3nanocomposite shows high catalytic activity for the photodegradation of the pollutantrhodamine B under simulated visible light irradiation, and the photocatalytic degradationratio of rhodamine B reaches to94.5%after70min of irradiation.