Interfacial sites in platinum-hydroxide-cobalt hybrid nanostructure for promoting CO oxidation activity
Interfacial sites in platinum-hydroxide-cobalt hybrid nanostructure for promoting CO oxidation activity
复制标题
铂-氢氧化物-钴杂化纳米结构中促进CO氧化活性的界面位点
DOI：
10.1039/d0nr07880h
复制
发表时间：
2021
期刊：
影响因子：
6.7
通讯作者：
Sun Zhihu
中科院分区：
文献类型：
--
作者：
He Wenxue;Huang Li;Liu Chengyong;Wang Siyu;Long Zhixin;Hu FengChun;Sun Zhihu
金属-氧化物/氢氧化物杂化纳米结构为研究界面效应对金属催化剂催化性能的影响提供了一个很好的平台。本文采用H_2O_2浸渍Co(OH)_2和尿素辅助沉积−沉淀铂纳米颗粒相结合的方法，制备了负载在SiO_2上的铂@Co(OH)_2杂化纳米结构。浸渍过程中Co~(2+)与H_2O_2之间的类Fenton反应促进了活性界面中心的形成。这种杂化纳米结构对CO氧化的催化活性远高于铂负载量和颗粒尺寸相近的铂/二氧化硅纳米颗粒。利用原位漫反射红外傅里叶变换光谱跟踪了CO的吸附过程，确定了CO氧化过程中的反应中间产物。结果表明，在铂-氢-钴界面处的羟基物种很容易与吸附在相邻铂上的CO反应生成CO_2，形成*COOH中间体和氧空位。在CO+O2氧化条件下，O2分子被氧空位激活，并与吸附在铂上的CO分子反应生成CO2，通过DRIFTS观察到高活性的*OOH中间体。
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.