Near-Unity Electrochemical CO2 to CO Conversion over Sn-Doped Copper Oxide Nanoparticles

Shuang Yang; Zhaochun Liu; Hongyu An; Sven Arnouts; Jim de Ruiter; Floriane Rollier; Sara Bals; Thomas Altantzis; Marta C Figueiredo; Ivo A W Filot; Emiel J M Hensen; Bert M Weckhuysen; Ward van der Stam

doi:10.1021/acscatal.2c04279

Near-Unity Electrochemical CO₂ to CO Conversion over Sn-Doped Copper Oxide Nanoparticles

ACS Catal. 2022 Dec 16;12(24):15146-15156. doi: 10.1021/acscatal.2c04279. Epub 2022 Nov 28.

Authors

Affiliations

¹ Inorganic Chemistry and Catalysis, Institute for Sustainable and Circular Chemistry and Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, Utrecht 3584 CG, The Netherlands.
² Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands.
³ Electron Microscopy for Materials Science (EMAT), University of Antwerp, Antwerp 2020, Belgium.
⁴ Applied Electrochemistry and Catalysis (ELCAT), University of Antwerp, 2610 Wilrijk, Belgium.

Abstract

Bimetallic electrocatalysts have emerged as a viable strategy to tune the electrocatalytic CO₂ reduction reaction (eCO₂RR) for the selective production of valuable base chemicals and fuels. However, obtaining high product selectivity and catalyst stability remain challenging, which hinders the practical application of eCO₂RR. In this work, it was found that a small doping concentration of tin (Sn) in copper oxide (CuO) has profound influence on the catalytic performance, boosting the Faradaic efficiency (FE) up to 98% for carbon monoxide (CO) at -0.75 V versus RHE, with prolonged stable performance (FE > 90%) for up to 15 h. Through a combination of ex situ and in situ characterization techniques, the in situ activation and reaction mechanism of the electrocatalyst at work was elucidated. In situ Raman spectroscopy measurements revealed that the binding energy of the crucial adsorbed *CO intermediate was lowered through Sn doping, thereby favoring gaseous CO desorption. This observation was confirmed by density functional theory, which further indicated that hydrogen adsorption and subsequent hydrogen evolution were hampered on the Sn-doped electrocatalysts, resulting in boosted CO formation. It was found that the pristine electrocatalysts consisted of CuO nanoparticles decorated with SnO₂ domains, as characterized by ex situ high-resolution scanning transmission electron microscopy and X-ray photoelectron spectroscopy measurements. These pristine nanoparticles were subsequently in situ converted into a catalytically active bimetallic Sn-doped Cu phase. Our work sheds light on the intimate relationship between the bimetallic structure and catalytic behavior, resulting in stable and selective oxide-derived Sn-doped Cu electrocatalysts.