Orbital Engineering via Double-Exchange Interaction in a Bimetallic MOF for Electrocatalytic C─S Coupling of CO₂ and...

Guided by molecular orbital theory, we have designed and synthesized a novel bimetallic metal-organic framework (BTC-Co-O-Cu-BTA) for the electrocatalytic C─S coupling of CO₂ and sulfate. The integration of edge/corner-sharing CoO₆ octahedra and CuO₅ square pyramids establishes a robust double-exchange interaction (DEI). This interaction effectively modulates the spin states of the cobalt and copper sites while optimizing their electronic configurations. This tailored electronic environment disrupts the hyperconjugation symmetry of the S─O bonds in sulfate, enabling the simultaneous activation of both CO₂ and sulfate. Consequently, the catalyst achieves highly efficient C─S coupling with a remarkable Faradaic efficiency of 17.43% under a pure CO₂ atmosphere, significantly outperforming conventional systems. Through in-situ FTIR, NMR, and electrochemical impedance spectroscopy, we demonstrate that this bimetallic synergy substantially lowers the reaction energy barrier and allows for the capture of key dynamic intermediates. Furthermore, magnetic measurements reveal a DEI-induced transition from an antiferromagnetic to a ferromagnetic electronic state, successfully validating our proposed orbital engineering mechanism. This work provides a novel strategy for activating inert chemical bonds and establishes fundamental principles for the design of high-performance electrocatalysts.