Nitrogen-doped carbon confined Cu-Ag bimetals for efficient electroreduction of CO2 to high-order products

Abstract

Electrochemical reduction of CO2 is a promising approach for storing the green electricity from intermittent solar and wind energy into chemical fuels. The direct production of energy-dense renewable synthetic fuels that is highly compatible with the existing transportation infrastructures is particularly important yet extraordinarily challenging. In this work, bimetallic Cu-Ag catalysts confined in a nitrogen-doped carbon octahedral shell are developed by a facile MOF-mediated synthesis for this grand objective. By correlative microscopic characterizations, theoretical and systematic experiments investigations, it is discovered that the bimetallic Cu-Ag nanoparticles work in synergy with the nitrogen-doped porous carbon octahedral shell for efficient electrocatalytic CO2 reduction reaction (CO2RR) towards high-order products. Owing to the geometric and electronic benefits, the as-designed electrocatalyst is favorable for C-C coupling through an interesting *CHO–*CO pathway with significantly lower energy barrier and enhanced mass transport of reactants and intermediates, thus leading to high activity and selectivity towards energy-dense products. The total faradaic efficiency of high-order products i.e., CH4, C2H4, C2H5OH and CH3COOH reaches 55.3% with a high current density of 5.3 mA/cm2 at a relatively low overpotential of −1.2 V versus reversible hydrogen electrode (RHE), exceeding the most common primary products e.g., H2, CO and HCOOH. This study presents that the rational assembly of Cu-derived bimetallic catalysts with confined nitrogen-doped carbon architecture to produce high-order products from electrocatalytic CO2 reduction.