摘要
采用简单的沉淀法制得Ag@AgCl纳米颗粒表面修饰三维花状Bi_2WO_6复合光催化剂(Ag@AgCl/Bi_2WO_6),利用XRD、UV-Vis、SEM、TEM、EDX、SAED及光电测试等对光催化剂的结构性能进行了表征,并考察了复合材料在可见光下对罗丹明B(RhB)降解反应的催化性能。研究表明:Ag@AgCl纳米颗粒平均粒径在50 nm左右,均匀地分散在Bi_2WO_6的表面上;贵金属Ag粒子的等离子共振效应极大地增强了复合材料对可见光的吸收利用;Ag@AgCl纳米粒子的引入可有效促进光生电荷的分离,实现复合材料光催化性能的提高。活性测试表明,0.25 g Ag@AgCl(20%,质量分数)/Bi_2WO_6光催化剂存在下,250 mL、10 mg/L的RhB溶液经可见光照射后降解率高达95%。另外,淬灭实验表明光催化降解过程中,·O_2~-、h~+和·OH充当了主要的活性物种。本工作还结合表征结果及实验数据对复合光催化剂的作用机理进行了分析。
Three-dimensional composites of flower-like Bi_2WO_6 decorated with Ag@AgCl nanoparticles(designated Ag@AgCl/Bi_2WO_6) were prepared via a simple precipitation method, and were subsequently characterized for structure and performance evalutation by using XRD, UV-Vis, SEM, TEM, EDX, SAED, and photoelectric test. Moreover, the products' photocatalytic activity was investigated by the degradation reaction of Rhodamine B(RhB) under visible light irradiation. The experimental results confirmed the uniform distribution of Ag@AgCl nanoparticles, with an average particle size of 50 nm, on the surface of Bi_2WO_6. The Ag@AgCl/Bi_2WO_6 composites exhibit excellent UV-vis absorption due to the surface plasmonic resonance(SPR) of Ag nanoparticles. Meanwhile, the introduction of Ag@AgCl nanoparticles can greatly accelerate the separation of photogenerated carriers, thus improving the photocatalytic activity of the resultant composite materials. In the photocatalysis test achieved a degradation rate as high as 95% of RhB(250 mL, 10 mg/L) with the presence of 0.25 g Ag@AgCl(20 wt%)/Bi_2WO_6 photocatalyst under visible light irradiation. In addition, it was determined by quenching test that the O_2~-, h~+ and ·OH acts as main active species during the photocatalytic degradation process. Based on the experimental and theoretical results, the possible photocatalytic mechanism was proposed.
引文
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