Construction of a self-supporting bifunctional Sn–SnSx electrocatalyst via one-step electrodeposition for formate production from coupled CO2 reduction and glucose oxidation

Abstract

The electroconversion of carbon dioxide (CO₂) into value-added chemicals has attracted widespread attention worldwide. Exploring efficient catalysts and designing reasonable reactants have become popular research directions in the strategy of coupling anode and cathode reactions. Herein, we report the construction of a self-supporting bifunctional Sn–SnS_x electrode using a one-step electrodeposition method. The valence states of Sn at the Sn–SnS_x surface are Sn⁴⁺, Sn²⁺ and Sn⁰, and the electrode exhibits excellent performances for the carbon dioxide reduction reaction (CO₂RR) and glucose oxidation reaction (GOR), respectively. For the CO₂RR, the Sn–SnS_x electrode produced formate with a faradaic efficiency (FE) of 93.3% and a stability of 36 h. Meanwhile, tin sulfides were first applied in anodic oxidation and a high FE of 88% was achieved for formate production in the GOR. Impressively, Sn–SnS_x as a bifunctional electrode achieved co-production of formate at both the anode and cathode in the integrated electrolyzer coupled with the CO₂RR and GOR. This coupling process combines the technical means of “electrooxidation–electroreduction” with the choice of reactants “CO₂–C₆H₁₂O₆”, resulting in FE values of 93.9% and 87.4% at the cathode and anode for the production of formate, as well as a 58.3% electrical energy saving for formate production in comparison with the traditional CO₂RR coupled with the water oxidation reaction.