PS@Au核壳复合粒子的可控合成及粒径对催化性能的影响

Controllable Synthesis of PS@Au Core-Shell Composite Particles and the Effect of Diameter on Catalytic Performance

采用适当的化学镀工艺,通过对核层聚苯乙烯微球粒径的调制,可控合成了粒径连续可调的PS@Au核壳复合粒子,其球形度较高,无团聚,催化活性优良。利用SEM、XRD和UV-Vis,结合催化性能测试,研究了粒径对PS@Au核壳复合粒子催化性能的影响。结果表明:PS@Au核壳复合粒子较大的比表面积是其取得优良催化性能的物理本质,此外,粒径对其表面微观形貌、Au纳米粒子的生长方式及其催化性能都有显著影响。粒径较小时,核层曲率较大,Au纳米粒子呈发散式生长,表现出孤立的纳米颗粒状结构。此时,比表面积和表面能最大,催化活性最高。随着粒径增大,曲率逐渐减小,Au纳米颗粒表现出近似的薄膜状结构,比表面积和表面能逐渐降低,催化性能逐渐下降。核壳复合粒子的粒径达到400 nm时,Au纳米粒子的表面形貌开始由孤立的颗粒状结构向连续薄膜状过度。

PS@Au core-shell composite particles with excellent catalytic performance, high sphericity and no agglomeration were eontrollably synthesized by a suitable electroless plating process. The diameter of PS@Au composite particles could be adjusted continuously through tuning diameter of polystyrene microspheres. The influence of diameter on catalytic performance of PS@Au composite particles was investigated by SEM, XRD, UV-Vis spectrometer, and the detection of catalytic performance. The results indicate that the high specific surface area is responsible for the improvement of degradation rate of methylene blue chromophore and the excellent catalytic performance of PS@Au core-shell composite particles. Moreover, the diameter has a significant effect on both surface morphology and growth mode of Au nanoparticles, and the catalytic performance of the composite particles. When the diameter of core-shell structure is small, the curvature of the polystyrene microspheres is huge. Au nanoparticles exhibit isolated and granular structure because the orientation distribution of Au nanoparticles is diffused. In this case, PS@Au composite particles show the superior catalytic performance due to the higher specific surface area and surface energy. On the contrary, with the diameter of core-shell structure increasing, the curvature decreases. Au nanoparticles with close orientation merge and grow up rapidly, which is a film-like material. As a result, specific surface area and surface energy are decreased as the diameter rises and their catalytic performance also declines. In this study, the microstructure of Au nanoparticles begins to change from granular structure to continuous film-like structure, when the diameter of PS@Au core-shell composite particles is up to 400 nm.