Unravelling the Structure Change and Its Catalytic Consequence of CuO Nanowires Towards CO₂ Reduction Reaction

The CO 2 reduction reaction (CO2RR) is a complex process with many possible products, and maintaining high selectivity for multi-carbon products remains a challenge. Currently, Cu-based catalysts are the only transition metal catalysts that can produce C2 products, and one of the popular Cu-based catalysts is CuO nanowires (NWs). We studied a series of CuO nanowires ranging from 50 to 200 nm for CO2RR using multiple characterization techniques including transmission electron microscopy(TEM), small angle X-ray scattering (SAXS) and in situ X-ray adsorption spectroscopy. We found that there could be an activation process required for such CuO NWs to serve as efficient CO2RR catalysts. The CuO can go through multiple steps resulting in the severe morphology changes during the activation process, confirmed by TEM and SAXS. In situ XAS results showed that the CuO NWs will be reduced from Cu(II) to Cu(0) during the reaction, consistent with our previous work(1). H-cell testing results also indicated the C2 production can be boosted after specific activation pathway, which highlights the importance of catalyst pre-treatment. These findings not only deepen our understanding of CO2RR mechanism but also provide fundamental insights for CO2RR catalysts synthesis. References (1) Soo Hong Lee, Ian Sullivan, David M. Larson, Guiji Liu, Francesca M. Toma, Chengxiang Xiang, and Walter S. Drisdell. ACS Catalysis, 2020, 10 (14), 8000-8011 Acknowledgement The authors acknowledge the funding support from the Laboratory Directed Research and Development Program of the Lawrence Berkeley National Laboratory under the U.S. Department of Energy Contract (No. DE-AC02-05CH11231).