Testing a Silver Nanowire Catalyst for the Selective CO₂ Reduction in a Gas Diffusion Electrode Half-cell Setup Enabling High Mass Transport Conditions

In this work, we discuss the application of a gas diffusion electrode (GDE) setup for benchmarking electrocatalysts for the reductive conversion of CO₂ (CO₂ RR: CO₂ reduction reaction). Applying a silver nanowire (Ag-NW) based catalyst, it is demonstrated that in the GDE setup conditions can be reached, which are relevant for the industrial conversion of CO₂ to CO. This reaction is part of the so-called 'Rheticus' process that uses the CO for the subsequent production of butanol and hexanol based on a fermentation approach. In contrast to conventional half-cell measurements using a liquid electrolyte, in the GDE setup CO₂ RR current densities comparable to technical cells (>100 mA cm^-2) are reached without suffering from mass transport limitations of the CO₂ reactant gas. The results are of particular importance for designing CO₂ RR catalysts exhibiting high faradaic efficiencies towards CO at technological reaction rates.