砚状ZnO/石墨烯复合物的制备及其光催化性能

Synthesis and Photocatalytic Performance of Ink Slab-Like ZnO/Graphene Composites

采用一步溶液法制备了具有砚状形貌的ZnO/石墨烯复合材料。利用扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)等研究不同制备条件下ZnO形貌、石墨烯的复合状态和砚状ZnO的生长机理;通过测试300W氙灯对甲基蓝溶液(MB)的光催化效率,研究制备条件、形貌结构对复合物的光催化性能的影响;通过对复合物光致发光(PL)光谱以及紫外-可见光谱测试,研究石墨烯复合物对光生电子-空穴对的复合以及光吸收效率的影响。研究结果表明,砚状ZnO的生长机理为"掏蚀机理";复合石墨烯增强了这种ZnO的光吸收效率、降低了ZnO的带隙,并且降低了光生电子-空穴对复合几率,有利于提高光催化性能;砚状ZnO的砚底上表面粗糙,有利于反应面积的增加,砚底的厚度较薄,有利于光生电子-空穴对在较强的内建电场下迅速向相反方向分离,降低其复合几率,从而使其具有优异的光催化性能。

A special ZnO/graphene composite with an ink slab-like shape was synthesized by a facile one-step solution method. The morphology of the ink slab-like ZnO/graphene composites produced under different reaction conditions was studied by scanning electron microscopy （SEM）, field emission SEM （FESEM）, and high resolution transmission electron microscopy （HRTEM）. The photocatalytic properties of the products obtained under different reaction conditions were evaluated to determine the effect of reaction conditions and morphology. Photoluminescence （PL） and UV-visible spectra were measured to study the recombination of electron-hole pairs and absorption of UV-visible light. The results showed that the growth process of the ink slab-like ZnO involves the ＇corrosion mechanism＇. The combination of graphene greatly enhanced the photocatalytic performance by enhancing light absorption, decreasing the band gap, and reducing the recombination probability of electron-hole pairs. Moreover, the bottom of the ink slab-like ZnO with a rough surface can greatly increase the reaction area. The extremely thin bottom of the ink slab offers a considerable build-in internal electric field that accelerates the separation of electron-hole pairs, thus decreasing the recombination probability and enhancing the photocatalytic performance.