Stabilized Cuδ+–OH species on Cu nanoparticles encapsulated in porous carbon nitride for electrocatalytic reduction of CO2 to ethylene

Abstract

Achieving large-scale electrochemical CO₂ reduction to multicarbon products with high selectivity is promising for carbon neutrality. However, the unsatisfactory multicarbon product selectivity and unclear reaction mechanisms have hindered its further development. Herein, we report a strategy that manipulates the interfacial microenvironment of Cu nanoparticles (Cu NPs) by incorporation with g-C₃N₄ to realize the reduction products’ shift from methane to ethylene. In situ characterization and theoretical calculations demonstrate that the formation of Cu–N bonds between Cu NPs and porous g-C₃N₄ creates the Cu^δ+ (0 < δ < 1) species. Such Cu^δ+ sites enhanced *OH (derived from water dissociation) adsorption through the formation of Cu^δ+–OH intermediates. The stabilized Cu^δ+–OH species lower the energy barrier for the asymmetric coupling of *CO and *CHO intermediates, steering the reaction pathway from methane to ethylene. The as-prepared Cu/200-C₃N₄ catalyst exhibits an exceptional ethylene selectivity (57%) even at a large current density of 600 mA cm⁻² in the flow cell. This study advances our understanding of the CO₂ reduction mechanism and offers an effective and general strategy for enhancing the electrocatalytic performance by regulating water dissociation.