CeO2/石墨烯的合成及其在光催化制氢中的应用

采用具有丰富分级多孔结构的豆芽为模板，经水热法合成仿生形态的纳米CeO₂/石墨烯催化剂。使用XRD、拉曼光谱（Raman）、TEM、场发射扫描电子显微镜（FESEM）、紫外-可见漫反射光谱（UV-Vis/DRS）、N₂吸附-脱附仪和光解水制氢系统等分析表征手段对CeO₂/石墨烯催化剂的结构、形貌及光催化性能进行分析。结果表明，所制备的CeO₂/石墨烯光催化剂不仅继承了豆芽模板高孔隙率和大比表面积的特点，而且保持了豆芽的形态和微观特征。该催化剂是由约5.6 nm CeO₂纳米晶与具有生物形态的仿生石墨烯片层结构结合而成。制得的CeO₂/石墨烯复合材料内部存在大量由CeO₂/石墨烯催化剂纳米颗粒堆积而成的纳米孔，其孔径集中分布于15~45 nm左右，这种微观结构使CeO₂/石墨烯催化剂具有超大的比表面积，提高了催化剂对光生电子空穴对的捕获能力。由紫外-可见漫反射吸收光谱可知，CeO₂/石墨烯复合材料的可见光利用率显著增强，光解水制氢效率6 h后可达到671 μmol（h · g）^-1，远高于标样CeO₂的51.67 μmol（h · g）^-1。

Synthesis of CeO2/graphene and its application in photocatalytic hydrogen production

The nano-sized CeO₂/graphene catalyst was synthesized by hydrothermal method using bean sprouts with rich and graded porous structure as template. XRD, Raman spectroscopy, TEM, field emission scanning electron microscopy (FESEM), UV-Vis diffuse reflectance spectroscopy (UV-Vis/DRS) were adopted to characterize the structure and morphology of CeO₂/graphene catalyst, as well as the photocatalytic performance. The results show that the prepared CeO₂/graphene photocatalyst not only inherits the characteristics of high porosity and large specific surface area of bean sprouts, but also maintains the morphological and microscopic characteristics of bean sprouts. The catalyst is composed of about 5.6 nm CeO₂ nanocrystals combined with a biologically morphic bionic graphene sheet structure. The as-prepared CeO₂/graphene composite possesses a large number of nanopores formed by the accumulation of catalyst nanoparticles, and their pore sizes distribute at about 15-45 nm, which makes the CeO₂/graphene catalyst have large specific surface area and improves the capture of the photo-generated electron-hole pairs ability. The visible light utilization efficiency of CeO₂/graphene composites is significantly enhanced by the UV-visible diffuse reflectance spectrum, and 671 μmol(h·g)^-1 is obtained after 6 h of photolytic water, which is much higher than that of the standard CeO₂ of 51.67 μmol(h·g)^-1.