Effect of catalyst ink preparation on formate production from CO2 electroreduction using Sn as electrocatalyst

Electrochemical CO2 reduction (eCO2RR) offers a sustainable way to produce fuels and chemicals using renewable energy sources. Tin (Sn) is employed as an eCO2RR catalyst primarily to produce formate, with its productivity closely bound to the catalyst ink preparation method and reaction conditions. Herein, we examine how the catalyst loading, binder choice, and current density influence the catalytic performance. Reducing catalyst loading from 10 mg/cm2 to 1.685 mg/cm2 and increasing current density in highly concentrated bicarbonate solutions significantly enhances the catalytic reaction, achieving a formate faradaic efficiency of 88% at a current density of -30 mA/cm² and a potential of -1.2VRHE. This approach lowers catalyst costs and suppresses Hydrogen Evolution Reaction (HER). Additionally, while modifying the electrode’s surface with binders leads to blocked active sites and increased resistance, PVDF remains a promising option due to its stability, strength, and conductivity. Regarding ink preparation, Nafion enhances formate production when applied as a surface coating rather than being pre-mixed in the catalyst ink. However, it still does not match the performance of binder-free systems since Sn-based catalysts intrinsically exhibit high catalytic activity, making binder contribution less significant. This research reveals how to optimize the catalyst ink recipes and binder usage to boost the conversion of CO2 to formate, offering crucial insights for designing a cost-efficient catalyst for high current density operations.