Phosphorus-Driven Dual d-Band Harmonization for Reversible Electrocatalysis

To develop effective electrocatalysts, the d-band center theory has been a reliable predictor of electrocatalytic activity in transition-metal-based catalysts. However, it fails to accurately describe magnetic systems influenced by spin polarization. Herein, phosphorus doping was introduced into cobalt diselenide on a hive-like carbon framework with nitrogen insertion (P-CoSe₂@NC), which significantly enhances electrocatalytic performance for reversible CO₂ conversion in an advanced Li-CO₂ battery with specific capacities around 17,000 mAh g^-1, high-rate performance, and good longevity exceeding 600 h in a pouch cell. Phosphorus doping induces lattice torsion in CoSe₂, leading to strain-caused changes in the d-band center across different crystal planes, which are linked with the redistribution of spin states. To address the limitations of the traditional single d-band center model, the dual center model reveals how phosphorus doping effectively harmonizes the competition between spin orbitals, originating from changes in higher spin states. Such equilibrium moderates interactions with electrochemical intermediates to lower reaction energy barriers, enhancing reversible electrocatalysis for Li-CO₂ batteries. Therefore, strain-induced changes in the d-band centers, coupled with alterations in spin states, underline the enhanced electrocatalytic performance observed. This work provides novel insights into regulating bifunctional electrocatalytic activities in spin-polarized systems through a dual d-band center approach, utilizing nonmetal doping to optimize performance.