Cu-Ni alloy decorating N-doped carbon nanosheets toward high-performance electrocatalysis of mildly acidic CO2 reduction

Abstract

Electrochemical CO2 reduction to value-added chemicals or fuels is a prospective strategy for facilitating the closing of the carbon loop. However, there still exist challenges in developing efficient catalysts and optimizing the electrolyzer components to meet industrial applications. Herein, nitrogen-doped “willow leaf” shaped carbon nanosheets modified with Cu-Ni alloy (CuNi-N-CNS) is designed for electrochemical CO2 reduction reaction (CO2RR), which shows high faradaic efficiency for CO of over 90% at a wide potential window ranging from −0.8 V to −1.0 V and robust durability with almost 100% of its initial selectivity after 36 h of electrolysis in H-type cell. Moreover, we evaluate its electrocatalytic activity in a self-assembly flow cell in a mildly acidic catholyte (CO2-saturated 3 M KCl solution, pH = 4.25), which can achieve a commercially viable current density of 420 mA cm−2 at −1.0 V versus reversible hydrogen electrode (vs. RHE) with CO selectivity above 95%. Experimental characterization and electrochemical analysis reveal that the synergistic effects of ultra-thin “willow leaf” structure and bimetallic alloy modification can not only increase electron transport efficiency but also decrease the reaction energy barrier of COOH* and promote the formation of CO.