Activating Inert Palmeirite Through Co Local-Environment Modulation and Spin Electrons Rearrangement for Superior Oxygen Evolution

Mo-based palmeirite oxide A₂Mo₃O₈ is an emerging electrocatalyst, exhibiting a bipartite honeycomb lattice consisting of tetrahedral and octahedral sites with good conductivity. However, palmeirite as promising catalyst in electrocatalytic remains rarely touched. The rational design and clarification of the correlation between geometrical configuration modulation and electrocatalytic properties are challenging. Herein, an innovative strategy is reported to anchor thiospinel Co₃S₄ nanoparticles onto the surface of the Co₂Mo₃O₈ nanosheet, which can trigger the spin electrons rearrangement, thus activating inert sites. According to the X-ray absorption spectroscopy, the Co²⁺─O─Co³⁺ bimetallic bridging sites with asymmetric bond polarization are constructed in the interface, which triggers a favorable spin transition of Co³⁺ from low to intermediate spin. Interestingly, the Co₂Mo₃O₈/Co₃S₄ exhibits remarkable oxygen evolution reaction performance with an overpotential of 227 mV at 10 mA cm⁻². At an industrial process temperature, it takes only 2.37 V for overall water splitting to obtain a large current density of 1 A cm⁻². The theoretical calculation results confirm that lattice distortion-related spin transition optimizes the intermediate energy, thus enhancing the adsorption of the ^*OOH. This work highlights the potential of palmeirite for achieving industrial overall seawater splitting by geometrical configuration modulation and spin electrons rearrangement.