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Instruments / Technical Area	Publication Details	Published
B18-Core EXAFS	Cascade NH3 oxidation and N2O decomposition via bifunctional Co and Cu catalysts Xuze Guan , Hiroyuki Asakura , Rong Han , Siyuan Xu , Hao-Xin Liu , Lu Chen , Zhangyi Yao , Jay Hon Cheung Yan , Tsunehiro Tanaka , Yuzheng Guo , Chun-Jiang Jia , Feng Ryan Wang Acs Catalysis DOI: 10.1021/acscatal.3c02392 Diamond Proposal Number(s): [23759, 24450, 14239] Open Access Show Abstract ▼ Abstract: The selective catalytic oxidation of NH3 (NH3–SCO) to N2 is an important reaction for the treatment of diesel engine exhaust. Co3O4 has the highest activity among non-noble metals but suffers from N2O release. Such N2O emissions have recently been regulated due to having a 300× higher greenhouse gas effect than CO2. Here, we design CuO-supported Co3O4 as a cascade catalyst for the selective oxidation of NH3 to N2. The NH3–SCO reaction on CuO–Co3O4 follows a de-N2O pathway. Co3O4 activates gaseous oxygen to form N2O. The high redox property of the CuO–Co3O4 interface promotes the breaking of the N–O bond in N2O to form N2. The addition of CuO–Co3O4 to the Pt–Al2O3 catalyst reduces the full NH3 conversion temperature by 50 K and improves the N2 selectivity by 20%. These findings provide a promising strategy for reducing N2O emissions and will contribute to the rational design and development of non-noble metal catalysts.	Oct 2023
B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS B18-Core EXAFS E01-JEM ARM 200CF	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 Acs Catalysis DOI: 10.1021/acscatal.2c04863 Diamond Proposal Number(s): [23759, 24450, 29094, 24197] Open Access Show Abstract ▼ 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 O2– 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 O2– 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 O2– in catalysis.	Nov 2022
	The electrophilicity of surface carbon species in the redox of CuO‐CeO2 catalysts Liqun Kang , Bolun Wang , Andreas T. Güntner , Siyuan Xu , Xuhao Wan , Yiyun Liu , Sushila Marlow , Yifei Ren , Diego Gianolio , Chiu C. Tang , Vadim Murzin , Hiroyuki Asakura , Qian He , Shaoliang Guan , Juan J. Velasco-Vélez , Sotiris E. Pratsinis , Yuzheng Guo , Feng Ryan Wang Angewandte Chemie International Edition DOI: 10.1002/anie.202102570 Open Access Show Abstract ▼ Abstract: Electronic metal‐support interaction (EMSI) describes the electron flow between metal sites and a metal oxide support. It is generally used to follow the mechanism of redox reactions. In the study of CuO‐CeO2 redox, an additional flow of electron from metallic Cu to surface carbon species is observed via a combination of operando X‐ray absorption spectroscopy, synchrotron X‐ray powder diffraction, near ambient pressure‐near edge X‐ray absorption fine structure, and diffuse reflectance infrared Fourier transform spectroscopy. An electronic metal‐support‐carbon interaction (EMSCI) is proposed to explain the reaction pathway of CO oxidation. The EMSCI provides a complete picture of the mass and electron flow, which will help predict and improve the catalytic performance in the selective activation of CO2 , carbonate or carbonyl species in C1 chemistry.	Mar 2021

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