High Specific Activity during Electrochemical CO2 Reduction through Homogeneous Deposition of Gold Nanoparticles on Gas Diffusion Electrodes

The electrochemical CO₂ reduction reaction (CO₂RR) has attracted attention as a promising strategy for converting CO₂ into value-added products. Gas diffusion electrodes (GDEs) loaded with metallic nanoparticles as electrocatalysts are expected to efficiently reduce CO₂ due to the high specific surface area of such particles and the superior mass transport characteristics of GDEs. In the present study, GDEs loaded with homogeneous layers of gold (Au) nanoparticles were fabricated using a radio frequency sputtering technique that had a low deposition rate. This allowed for precise control of the catalyst loading. The Au-loaded GDEs exhibited a significantly higher CO production efficiency compared with the electrodes fabricated by conventional deposition methods using dispersed Au nanoparticles. Additionally, a Au-loaded GDE having a catalytic layer thickness of 10 nm demonstrated a mass-based CO production activity of 1882 A g^–1 at −0.85 V. This is the highest value yet reported. This work confirmed that the uniform deposition of metallic nanoparticles provides enhanced catalyst utilization. The results of this research provide important insights into the design of efficient CO₂RR electrodes and highlight the potential of radio frequency sputtering to fabricate high-performance CO₂RR electrodes as an approach to realizing carbon-neutral technologies.