Designing Reactive Bridging O2- at the Atomic Cu-O-Fe Site for Selective NH3 Oxidation

Xuze Guan; Rong Han; Hiroyuki Asakura; Zhipeng Wang; Siyuan Xu; Bolun Wang; Liqun Kang; Yiyun Liu; Sushila Marlow; Tsunehiro Tanaka; Yuzheng Guo; Feng Ryan Wang

doi:10.1021/acscatal.2c04863

Designing Reactive Bridging O^2- at the Atomic Cu-O-Fe Site for Selective NH₃ Oxidation

ACS Catal. 2022 Dec 16;12(24):15207-15217. doi: 10.1021/acscatal.2c04863. Epub 2022 Nov 29.

Authors

Xuze Guan¹, Rong Han², Hiroyuki Asakura^{3

4}, Zhipeng Wang¹, Siyuan Xu², Bolun Wang¹, Liqun Kang¹, Yiyun Liu¹, Sushila Marlow¹, Tsunehiro Tanaka⁴, Yuzheng Guo², Feng Ryan Wang¹

Affiliations

¹ Department of Chemical Engineering, University College London, Roberts Building, Torrington Place, LondonWC1E 7JE, U.K.
² School of Electrical Engineering and Automation, Wuhan University, Wuhan430072, China.
³ Functional Materials Lab, Faculty of Science and Engineering, Kindai University 3-4-1, Kowakae, Higashi-Osaka, Osaka577-8502, Japan.
⁴ Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyotodaigaku Katsura, Nishikyo-ku, Kyoto615-8510, Japan.

Abstract

Surface oxidation chemistry involves the formation and breaking of metal-oxygen (M-O) bonds. Ideally, the M-O bonding strength determines the rate of oxygen absorption and dissociation. Here, we design reactive bridging O^2- species within the atomic Cu-O-Fe site to accelerate such oxidation chemistry. Using in situ X-ray absorption spectroscopy at the O K-edge and density functional theory calculations, it is found that such bridging O^2- has a lower antibonding orbital energy and thus weaker Cu-O/Fe-O strength. In selective NH₃ oxidation, the weak Cu-O/Fe-O bond enables fast Cu redox for NH₃ conversion and direct NO adsorption via Cu-O-NO to promote N-N coupling toward N₂. As a result, 99% N₂ selectivity at 100% conversion is achieved at 573 K, exceeding most of the reported results. This result suggests the importance to design, determine, and utilize the unique features of bridging O^2- in catalysis.