A Non-Noble Metal Catalyst-Based Electrolyzer for Efficient CO₂‑to-Formate Conversion

Abstract

Electrochemical CO2 reduction offers a promising approach to alleviate environmental and climate impacts attributed to increasing atmospheric CO2. Intensive research work has been performed over the years on catalysts, membranes, and other associated components related to the development of CO2 electrolyzers. Herein, we assembled a full cell comprising a Bi nanoparticle (NP)-based cathode for reducing CO2 to formate and the earth-abundant NiFe layered double hydroxide (LDH)-based anode for oxygen evolution. The electrolyte used was 1 M KOH, and an anion exchange membrane separator was employed. A formate conversion Faradaic efficiency (FEformate) of 90 ± 2% was obtained at the cell voltage of 2.12 V. This full cell system operating at 2.12 V was found to perform well over 10 h, as the FEformate remained above 85% with ∼82% retention of current. This is among the best performing CO2-to-formate conversion systems based on all non-precious metal catalysts. The low water oxidation overpotential of NiFe LDH, coupled with the highly efficient Bi NPs CO2 reduction catalyst, and the use of KOH electrolyte operated under flow cell configuration that maximizes the reactant/product mass transfer all contribute to this high-performance electrolyzer