Artificial Photosynthesis Lab

The electrochemical reduction of CO₂ faces challenges and increased costs owing to the short lifetime of its gas diffusion electrodes (GDEs). Bi-based GDEs appear promising for converting CO₂ to formate, achieving high current density and Faradaic efficiency. However, their instability, particularly at high current densities, remains a problem. Our findings indicate that the formate produced during the reaction is likely the primary cause of GDE deactivation, leading to >40% of the catalyst dissolving within 40 min of operation. To address this limitation, this work demonstrates that incorporating Sb into the structure of a GDE increases its duration of stable operation by a factor of six. The enhancement is attributed to two main factors: (i) improved corrosion resistance, likely due to effects arising from the formation of an alloy with Sb, and (ii) the initiation of dynamic redeposition of the electrocatalyst. This redeposition offers the GDE a degree of self-repairing, a phenomenon not observed without a bias potential or Sb. Our finding that Sb can help stabilize GDEs contributes to the growing interest in developing dynamic processes to enhance the durability of energy devices, rather than seeking inherently more stable materials.