Highly efficient CO2 reduction on ordered porous Cu electrode derived from Cu2O inverse opals

Electrochemical reduction of CO2 to fuels is a promising way to reduce CO2 emission and address the environment and energy crisis. However, the H-2 evolution reaction competes with CO2 electrochemical reduction, which would lower the overall efficiency for carbonaceous products. In this work, a new electrocatalyst (cubic-shaped Cu inverse opals) was reported to reduce CO2 to useful chemicals, which was synthesized from an electrochemical reduction of Cu2O inverse opals. The Cu inverse opals could electrochemically reduce CO2 to CO and HCOOH with a Faradaic efficiency of 45.3% and 33.6%, which was 3 times and 5 times higher than that of Cu particles film at identical conditions. The improved Faradaic efficiency for CO2 reduction was ascribed to the enhanced stabilization for the CO2 center dot- intermediate on the high surface area of Cu inverse opals, and the greatly improved reactant diffusion in this interconnected and ordered macroporous structure. The design of Cu inverse opals presents a prospective application of inverse opals in CO2 reduction through constructing inverse-opal structure as groundwork, which may provide key structure-activity insights for efficient CO2 reduction.