采用水热法制备粒径为1～2 μm的BiVO4微米片,然后在微米片表面沉积不同含量的Ag2CO3颗粒,制备Ag2CO3/BiVO4复合微米片光催化剂.利用X射线粉末衍射(XRD)、扫描电镜(SEM)、红外光谱(FTIR)、紫外-可见漫反射光谱(UV-Vis DRS)、光致发光(PL)光谱、瞬态光电流-时间响应对催化剂进行表征.以可见光为光源,罗丹明B为降解对象进行光催化活性测试.结果表明,复合适量Ag2CO3有利于提高光催化剂的比表面积,改善催化剂的表面性能.活性测试结果表明,当复合10％(w/w)Ag2CO3时,Ag2CO3/BiVO4光催化活性最佳,比纯BiVO4提高4.4倍.光致发光(PL)光谱、瞬态光电流-时间响应测试结果表明,复合Ag2CO3能有效抑制光生电子与空穴的复合.自由基捕获实验结果表明,该体系的活性氧物质为空穴和羟基自由基.Ag2CO3/BiVO4复合光催化剂活性提高的原因,是较宽带隙的Ag2CO3与较窄带隙的BiVO4形成的异质结有效抑制了光生电子与空穴的复合,同时两者适宜的能带结构保证产生更多的空穴,从而具有更强的氧化能力.%BiVO4 microsheets with particle size of 1 ～2 μm were fabricated by hydrothermal method.Then,Ag2CO3/BiVO4 composite microsheet photocatalysts with different contents of Ag2CO3 were synthesized via precipitation method.The products were characterized by powder X-ray diffraction (XRD),scanning electron microscopy (SEM),Fourier transform-infrared (FTIR) spectroscopy,UV-Vis diffuse reflectance spectroscopy (DRS),photoluminescence (PL) emission spectroscopy,transient photocurrent-time response.The photocatalytic activity of the samples were evaluated by photocatalytic degradation of rhodamine B under visible light irradiation.The results showed that loading of Ag2CO3 was beneficial to improve the specific surface area and surface properties of the catalyst.Activity test indicated that BiVO4 loaded with optimal l0％(w/w)Ag2CO3 resulted in 4.4 times increase in activity with respect to BiVO4 under visible light illumination.The results of photoluminescence (PL) emission spectroscopy and transient photocurrent-time response showed that the coupled Ag2CO3 can effectively inhibit the recombination of photogenerated electrons and holes.Active radicals trapping experiments indicated that hole and hydroxyl radicals were the reactive oxygen species in this Ag2CO3/BiVO4 system.The enhancement in activity of Ag2CO3/BiVO4 could be attributed to the heterojunction structure formed by Ag2CO3 with wider band gap and BiVO4 with narrower band gap.This heterojunction effectively restrained the recombination of photogenerated electrons and holes.Moreover,the suitable energy band structure brought about strong oxidation ability due to more holes were produced.
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