Differentiating the Impacts of Cu<sub>2</sub>O Initial Low‐ and High‐Index Facets on Their Reconstruction and Catalytic Performance in Electrochemical CO<sub>2</sub> Reduction Reaction
Han Chen, Varun Kundi, Zhipeng Ma, Cui Ying Toe, Priyank V. Kumar, Constantine Tsounis, Junjie Jiang, Shibo Xi, Zhaojun Han, Xunyu Lu, Rose Amal, Jian Pan
Abstract
Abstract Oxide‐derived Cu catalysts from Cu 2 O microcrystals are capable of electrochemically converting CO 2 into various value‐added chemicals. However, their structural transformation and associated preferred products remain unclear, requiring further investigation. Herein, Cu 2 O microcrystals with controllable low‐ and high‐index facets exposure are fabricated to differentiate the effects of initial exposed facets on their structural reconstruction and product selectivity in electrochemical CO 2 reduction reaction. Combined in situ characterizations and theoretical investigation reveal the direct correlations of Cu 2 O reconstruction and product selectivity to its initial facet exposure. The Cu 2 O low‐index facet, being more stable with a high energy barrier on material reduction, tends to partially maintain its original crystalline structure and larger Cu 2 O particle size throughout the transformation. The derived flatter surface and limited Cu 2 O/Cu interfaces result in a favorable selectivity toward 2‐electron transfer products. The chemically active Cu 2 O high‐index facet (311) is energetically favorable to be reduced owing to the feasible protonation process, thus experiencing a drastic reconstruction with rich newly formed Cu nanoparticles and evolved fine Cu 2 O grains; Such a reconstruction creates uncoordinated Cu species and abundant boundaries, benefiting charge transfer and increasing the local pH by confining OH − , thus leading to a high selectivity toward C 2+ products.