Ligand‐Driven Electron‐Deficient Cobalt Pentlandite Nanocrystals for Efficient Hydrogen Peroxide Electrosynthesis

Cobalt pentlandite (Co 9 S 8 ) is a promising non‐precious catalyst due to its superior oxygen reduction reaction activity and excellent stability. However, its oxygen reduction reaction catalytic activity has traditionally been limited to the four‐electron pathway because of strong *OOH intermediate adsorption. In this study, we synthesized electron‐deficient Co 9 S 8 nanocrystals with an increased number of Co 3+ states compared to conventional Co 9 S 8 . This was achieved by incorporating a high density of surface ligands in small‐sized Co 9 S 8 nanocrystals, which enabled the transition of the electrochemical reduction pathway from four‐electron oxygen reduction reaction to two‐electron oxygen reduction reaction by decreasing *OOH adsorption strength. As a result, the Co 3+ ‐enriched Co 9 S 8 nanocrystals exhibited a high onset potential of 0.64 V (vs RHE) for two‐electron oxygen reduction reaction, achieving H 2 O 2 selectivity of 70–80% over the potential range from 0.05 to 0.6 V. Additionally, these nanocrystals demonstrated a stable H 2 O 2 electrosynthesis at a rate of 459.12 mmol g −1 h −1 with a H 2 O 2 Faradaic efficiency over 90% under alkaline conditions. This study provides insights into nanoscale catalyst design for modulating electrochemical reactions.