Conjugated Coordination Polymer Aerogels with Unsaturated Single-Atom Metal Sites for Efficient Neutral Oxygen Evolution.

Designing high-performance single-atom catalysts with a precisely designed configuration is important in extensive energy-conversion technologies, which presents enormous potentials to be extensively applied. Defect-enriched conjugated coordination polymer aerogels (d-CCPAs) with abundant coordinatively unsaturated single-atom metal sites and the counterpart conjugated coordination polymer aerogel were developed, with Ni1-O2 and Ni1-O4 motifs employed as model systems for comparative investigation. Our findings reveal that the Ni1-O2 sites with elevated Ni d-band centers lower the thermodynamic barrier for the neutral OER, while the defective structure of d-CCPA accelerates reactant transport and improves active-site accessibility. Consequently, the d-CCPA delivers an ultralow overpotential of 213 mV at 10 mA/cm2 and maintains good durability over 400 h. Such d-CCPA catalysts feature exceptional tunability of active sites given the diversities of metal precursors and organic ligands, holding immense potential for application in widespread catalytic reactions.