Ethylene Selectivity in Electrocatalytic CO Reduction on Cu Nanomaterials: A Crystal Phase-Dependent Study.

The crystal phase of metal nanocatalysts significantly affects their catalytic performance. Cu-based nanomaterials are unique electrocatalysts for CO reduction reaction (CORR) to produce high-value hydrocarbons. However, studies to date are limited to the conventional face-centered cubic () Cu. Here, we report a crystal phase-dependent catalytic behavior of Cu, after the successful synthesis of high-purity 4H Cu and heterophase 4H/ Cu using the 4H and 4H/ Au as templates, respectively. Remarkably, the obtained unconventional crystal structures of Cu exhibit enhanced overall activity and higher ethylene (CH) selectivity in CORR compared to the Cu. Density functional theory calculations suggest that the 4H phase and 4H/ interface of Cu favor the CH formation pathway compared to the Cu, leading to the crystal phase-dependent CH selectivity. This study demonstrates the importance of crystal phase engineering of metal nanocatalysts for electrocatalytic reactions, offering a new strategy to prepare novel catalysts with unconventional phases for various applications.