Highly Efficient Electrocatalytic CO2 Reduction to C2+ Products on a Poly(ionic liquid)-Based Cu0-CuI Tandem Catalyst

Electroreduction of CO2 on a polymer-modified Cu-based catalyst has shown high multi-electron reduction (>2 e(-)) selectivity, however, most of the corresponding current densities are still too small to support industrial applications. In this work, we designed a poly(ionic liquid) (PIL)-based Cu-0-Cu-I tandem catalyst for the production of C2+ products with both high reaction rate and high selectivity. Remarkably, a high C2+ faradaic efficiency (FEC2+) of 76.1 % with a high partial current density of 304.2 mA cm(-2) is obtained. Mechanistic studies reveal the numbers and highly dispersed Cu-0-PIL-Cu-I interfaces are vital for such reactivity. Specifically, Cu nanoparticles derived Cu-0-PIL interfaces account for high current density and a moderate C(2+ )selectivity, whereas Cu-I species derived PIL-Cu-I interfaces exhibit high activity for C-C coupling with the local enriched *CO intermediate. Furthermore, the presence of the PIL layer promotes the C2+ selectivity by lowering the barrier of C-C coupling.