用于 CO 氧化的 Pd-Au 双金属纳米催化剂中活性位的原位形成：NAP（近环境压力）XPS 和 MS 研究。

In situ formation of the active sites in Pd-Au bimetallic nanocatalysts for CO oxidation: NAP (near ambient pressure) XPS and MS study.

机构信息

Boreskov Institute of Catalysis, SB RAS, Lavrentieva Ave. 5, Novosibirsk, 630090, Russia.

出版信息

Faraday Discuss. 2018 Sep 3;208(0):255-268. doi: 10.1039/c7fd00219j.

Abstract

Model bimetallic Pd-Au/HOPG catalysts have been investigated in the CO oxidation reaction using a combination of NAP XPS and MS techniques. The samples have shown catalytic activity at temperatures above 150 °C. The redistribution of Au and Pd on the surface depending on the reaction conditions has been demonstrated using NAP XPS. The Pd enrichment of the bimetallic particles' surface under reaction gas mixture has been shown. Apparently, CO adsorption induces Pd segregation on the surface. Heating the sample under reaction conditions above 150 °C decomposes the Pd-CO state due to CO desorption and reaction and simultaneous Pd-Au alloy formation on the surface takes place. Cooling back down to RT results in reversible Pd segregation due to Pd-CO formation and the sample becomes inactive. It has been shown that in situ studies are necessary for investigation of the active sites in Pd-Au bimetallic systems.

摘要

采用 NAP XPS 和 MS 技术相结合的方法研究了 CO 氧化反应中模型双金属 Pd-Au/HOPG 催化剂。在 150°C 以上的温度下，样品表现出催化活性。NAP XPS 表明，表面上的 Au 和 Pd 会根据反应条件重新分布。反应气体混合物下的双金属颗粒表面 Pd 富集现象得到证实。显然，CO 吸附会导致 Pd 在表面上的偏析。在 150°C 以上的反应条件下加热样品，由于 CO 脱附和反应，Pd-CO 状态会分解，同时在表面上形成 Pd-Au 合金。冷却回室温会导致由于 Pd-CO 的形成而发生可逆的 Pd 偏析，从而使样品失活。研究表明，对于 Pd-Au 双金属体系中活性位的研究，原位研究是必要的。