He Wenxue, Huang Li, Liu Chengyong, Wang Siyu, Long Zhixin, Hu Fengchun, Sun Zhihu
National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, P. R. China.
Nanoscale. 2021 Feb 4;13(4):2593-2600. doi: 10.1039/d0nr07880h.
Metal-oxide/hydroxide hybrid nanostructures provide an excellent platform to study the interfacial effects on tailoring the catalysis of metal catalysts. Herein, a hybrid nanostructure of Pt@Co(OH)2 supported on SiO2 was synthesized by incipient wetness impregnation of Co(OH)2 with the aid of H2O2 and successive urea-assisted deposition-precipitation of platinum nanoparticles. The Fenton-like reaction between Co2+ and H2O2 during the impregnation process facilitates the formation of active interfacial sites. This hybrid nanostructure exhibits much higher catalytic activity towards CO oxidation than Pt/SiO2 nanoparticles with a similar Pt loading and particle size. In situ diffuse reflectance infrared Fourier transform spectroscopy was used to track the CO adsorption processes and to identify the reaction intermediates during CO oxidation. It shows that the OH species at the Pt-OH-Co interfacial sites could readily react with CO adsorbed on neighboring Pt to yield CO2 by forming *COOH intermediates and oxygen vacancies. Under the CO + O2 oxidation conditions, O2 molecules are activated by the oxygen vacancy and react with the CO molecules adsorbed on Pt to generate CO2, via forming the highly active *OOH intermediates as observed by DRIFTS.
金属氧化物/氢氧化物杂化纳米结构为研究界面效应以定制金属催化剂的催化性能提供了一个极佳的平台。在此，通过借助过氧化氢对氢氧化钴进行初湿浸渍以及随后尿素辅助的铂纳米颗粒沉积沉淀法，合成了负载在二氧化硅上的Pt@Co(OH)₂杂化纳米结构。浸渍过程中钴离子与过氧化氢之间的类芬顿反应促进了活性界面位点的形成。与具有相似铂负载量和粒径的Pt/SiO₂纳米颗粒相比，这种杂化纳米结构对一氧化碳氧化表现出更高的催化活性。采用原位漫反射红外傅里叶变换光谱来追踪一氧化碳的吸附过程，并识别一氧化碳氧化过程中的反应中间体。结果表明，Pt-OH-Co界面位点处的羟基物种能够轻易地与吸附在相邻铂上的一氧化碳反应，通过形成COOH中间体和氧空位生成二氧化碳。在一氧化碳 + 氧气氧化条件下，氧气分子被氧空位激活，并与吸附在铂上的一氧化碳分子反应生成二氧化碳，如漫反射红外傅里叶变换光谱所观察到的，这是通过形成高活性的OOH中间体实现的。
