Nickel oxide/copper nanocluster anchored in carbon-nitride nanosheets realizing ultrahigh stability and broad potential range for zero-gap membrane flow reactor towards CO₂-into-CO electroreduction

CO₂ electrochemical reduction is a sustainable approach to achieve chemical fixation of CO₂ and storage of renewable energy. However, the catalyst which has the ability of mediating CO₂ to a single product with a relatively high current density is highly demand. Herein, we reported a metallic nitrogen-carbon catalyst based on two kinds of metal phthalocyanines by a facile synthesis method. The synergistic effect of Cu and Ni and the active sites of nickel oxide/copper nanocluster endow the catalyst excellent performance towards CO₂-into-CO electroreduction. Typically, the Cu-Ni bimetallic catalyst achieves high selectivity (85.2 %) at positive potential (-0.72 V_RHE), with the stability of current density and product selectivity beyond 72 h. The volume ratio of CO/H₂ can be effectively tuned (from 2:1, 1:1 to 1:2) by controlling the electrolysis potential, which is promising for synthesis gas in the Fischer-Tropsch reactions and methanol synthesis. Furthermore, the advantages are further amplified by applying it to zero-gap membrane flow reactor, which can enhance the selectivity over 90 % at a broad potential range (-2.5 ∼ -2.7 V) and achieve an current density of 9-fold of H-type cell. Our work proves a way for optimizing the CO₂ electrocatalyst and electrolyzers.