A Bidentate Chelation Strategy for Breaking the Thermodynamic Hydrophobicity-Activity Trade-Off to Boost the...

Achieving industrially relevant electrochemical CO₂ reduction (CO₂RR) to formic acid requires catalyst that simultaneously exhibits high intrinsic activity and surface hydrophobicity. However, high intrinsic activity is considered thermodynamically contradictory on a hydrophobic surface since high hydrophobicity corresponds to low surface energy, thereby leading to low intrinsic activity. Here we overcome this hydrophobicity-activity trade-off via a bidentate chelation strategy that grafts carboxylic acid molecules with tunable alkyl chain lengths on Bi₂O₂CO₃ (XC-BOC, where X denotes the carbon number). The obtained 10C-BOC sustains high hydrophobicity without sacrificing activity. This hydrophobicity-activity balance is achieved by restructuring the interfacial hydrogen-bond (HB) network to suppress the undesired hydrogen evolution reaction (HER) and ensure the timely hydrogenation rate for the key *OCHO intermediate, in conjunction with modulating the Bi site electronic structure via the carboxyl-O/Bi bidentate chelation to guarantee the high intrinsic activity. Consequently, 10C-BOC achieves ampere-level performance with FE_HCOO- > 90% from 100-1000 mA cm^-2, with an optimal FE_HCOO- of 97.7% at 600 mA cm^-2 (vs. 83.2% for bare BOC), and maintains FE_HCOO- > 93% at 200 mA cm^-2 for 200 h. This work offers a general strategy to decouple hydrophobicity from intrinsic activity for advanced CO₂RR electrocatalysts.