Revealing the Lattice Carbonate Mediated Mechanism in Cu2(OH)2CO3 for Electrocatalytic Reduction of CO2 to C2H4

Abstract Understanding the CO 2 transformation mechanism on materials is essential for the design of efficient electrocatalysts for CO 2 reduction. In aconventional adsorbate evolution mechanism (AEM), the catalysts encounter multiple high‐energy barrier steps, especially CO 2 activation, limiting the activity and selectivity. Here, lattice carbonate from Cu 2 (OH) 2 CO 3 is revealed to be a mediator between CO 2 molecules and catalyst during CO 2 electroreduction by a 13 C isotope labeling method, which can bypass the high energy barrier of CO 2 activation and strongly enhance the performance. With the lattice carbonate mediated mechanism (LCMM), the Cu 2 (OH) 2 CO 3 electrode exhibited ten‐fold faradaic efficiency and 15‐fold current density for ethylene production than the Cu 2 O electrode with AEM at a low overpotential. Theoretical calculations and in situ Raman spectroscopy results show that symmetric vibration of carbonate is precisely enhanced on the catalyst surface with LCMM, leading to faster electron transfer, and lower energy barriers of CO 2 activation and carbon–carbon coupling. This work provides a route to develop efficient electrocatalysts for CO 2 reduction based on lattice‐mediated mechanism.