Intrinsically Active Surface in a Pt/γ-Mo2N Catalyst for the Water-Gas Shift Reaction: Molybdenum Nitride or Molybdenum Oxide?

Zhe-Shan Zhang; Qiang Fu; Kai Xu; Wei-Wei Wang; Xin-Pu Fu; Xu-Sheng Zheng; Ke Wu; Chao Ma; Rui Si; Chun-Jiang Jia; Ling-Dong Sun; Chun-Hua Yan

doi:10.1021/jacs.9b11088

Intrinsically Active Surface in a Pt/γ-Mo₂N Catalyst for the Water-Gas Shift Reaction: Molybdenum Nitride or Molybdenum Oxide?

J Am Chem Soc. 2020 Aug 5;142(31):13362-13371. doi: 10.1021/jacs.9b11088. Epub 2020 Jul 27.

Authors

Zhe-Shan Zhang¹, Qiang Fu¹, Kai Xu¹, Wei-Wei Wang¹, Xin-Pu Fu¹, Xu-Sheng Zheng², Ke Wu³, Chao Ma⁴, Rui Si⁵, Chun-Jiang Jia¹, Ling-Dong Sun³, Chun-Hua Yan³

Affiliations

¹ Key Laboratory for Colloid and Interface Chemistry, Key Laboratory of Special Aggregated Materials, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China.
² National Synchrotron Radiation Laboratory, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China.
³ Beijing National Laboratory for Molecular Sciences, State Key Lab of Rare Earth Materials Chemistry and Applications, PKU-HKU Joint Lab in Rare Earth Materials and Bioinorganic Chemistry, Peking University, Beijing 100871, China.
⁴ College of Materials Science and Engineering, Hunan University, Changsha 410082, China.
⁵ Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, China.

PMID: 32658462
DOI: 10.1021/jacs.9b11088

Abstract

Apart from active metals, supports also contribute significantly to the catalytic performance of supported metal catalysts. On account of the formed strain and defects, the heterostructured surface of the support may play a crucial role to activate the reactant molecules, while it is usually neglected. In this work, the Pt/γ-Mo₂N catalyst was prepared via a facile solution method. This Pt/γ-Mo₂N catalyst showed excellent activity and stability for catalyzing the water-gas shift (WGS) reaction. The reaction rates at 240 °C were 16.5 mol_CO mol_Pt^-1s^-1 in product-free gas and 5.36 mol_CO mol_Pt^-1 s^-1 in full reformate gas, which were almost 20 times that of the catalysts reported. It is found that the molybdenum species in the surface of the Pt/γ-Mo₂N catalyst is molybdenum oxide as MoO₃. This surface MoO₃ is very easily reduced even at room temperature, and it transformed into highly distorted MoO_x (2 < x < 3) in the WGS reaction. The MoO_x on the catalyst surface greatly enhanced the capability of generating active oxygen vacancies to dissociate H₂O molecules, which induced unexpectedly superior catalytic performance. Therefore, the intrinsically active surface in the Pt/γ-Mo₂N catalyst for the WGS reaction was molybdenum oxide as MoO_x (2 < x < 3).