Intensified coupled electrolysis of CO2 and brine over electrocatalysts with ordered mesoporous transport channels

Abstract

The matched anodic and cathodic electrolysis can potentially increase the energy efficiency and produce value-added products simultaneously at both sides, and thus has attracted tremendous research interests. The success for a coupled electrolysis relies on not only the appropriate anodic and cathodic reaction pairs but also the suitable electrocatalysts that show high intrinsic activity, barrier-free ionic and electronic transport to the catalytic centers. Towards this goal, we showcased an efficient coupled electrolysis composed of the chloride oxidation reaction and the CO2 reduction reaction, in which the hexagonally ordered mesoporous electrocatalysts in terms of cobalt oxide and nickel, nitrogen co-doped carbons were used as anodic and cathodic electrocatalysts, respectively. Benefiting from the unique mesoporous structures, both the anodic and cathodic reactions exhibited prominent electrocatalytic performance in chloride salt electrolyte. Impressively, the coupled electrolysis showed a Faraday efficiency of 97% and 87% for CO and ClO−, respectively at cell voltage of ca. 2.5 V and current density of 20 mA cm−2. By doing so, a reduction in cell voltage by 1.8 V and an increase in energy efficiency by 40% were obtained as compared to the conventional system composed of cathodic CO2 reduction and anodic O2 evolution. This work not only highlights the importance of ordered mesoporous transport channels in accelerating the catalytic kinetics, but also showcases a high-performance coupled model for overall electrolysis.