Coupling Electrochemical Sulfion Oxidation with CO₂ Reduction over Highly Dispersed p‐Bi Nanosheets and CO₂‐Assisted Sulfur Extraction

Abstract

We report herein an electrocatalytic CO₂ reduction-coupled sulfion oxidation system for the co-productions of valuable formate and sulfur at much enhanced atom utilization. Specifically, an organic ligand-assisted two-step reconstruction approach has been developed to fabricate the highly dispersed p-Bi nanosheets (p-Bi NSs) for cathodic CO₂ reduction reaction (CO₂ RR), and meanwhile porous Co-S nanosheets (Co-S NSs) was applied for anodic sulfion oxidation reaction (SOR). Significantly high Faradaic Efficiencies of about 90 % for formate production by CO₂ RR in a wide potential range from -0.6 V to -1.1 V, and excellent SOR performances including an ultra-low onset potential of about 0.2 V and recycle capacity of S^2- in the 0.1 M and 0.5 M S^2- solutions, have been simultaneously achieved. In the meantime, both the structure transformation of the catalysts and the reaction pathways are explored and discussed in detail. A two-electrode CO₂ RR||SOR electrolyzer equipped with above electrocatalysts has been established, which features as low as about 1.5 V to run the electrolyzer at 100 mA cm^-2 , manifesting extremely lowered electricity consumption in comparison to conventional CO₂ RR system. Moreover, a sulfur separation approach has been proposed by using CO₂ , which is efficient, environmentally friendly and cost effective with value-added NaHCO₃ be obtained as the byproduct.