Metastable nitrides constructed via shape anisotropy-driven magnetothermal synergy for oxygen evolution reaction

The precise construction of high-energy catalytic interfaces is often impeded by the thermal inertia of conventional synthesis, where thermodynamic equilibrium leads to the agglomeration of nanostructures and the relaxation of metastable active sites. Herein, we report a strategy of nano-interfacial engineering enabled by shape anisotropy-driven magnetothermal synergy to overcome these limitations. Unlike traditional heating techniques, we introduce NiCo₂O₄ nanoneedles as active magnetothermal antennas, leveraging their specific shape anisotropy to maximize magnetic coupling via enhanced Néel relaxation. This geometric design induces localized, ultrafast thermal shocks (heating rate ∼13.6 °C s^-1) directly at the reaction interface. Consequently, the in situ grown nitride electrocatalysts achieve a kinetic locking of metastable Co³⁺ species and preserve the pristine nanostructured morphology, which are otherwise lost in equilibrium processing. The resulting catalyst delivers a superior oxygen evolution overpotential of 289 mV at 100 mA cm^-2, significantly outperforming thermodynamic equilibrium-controlled counterparts. Additionally, the system demonstrates robust overall water splitting performance (1.66 V at 10 mA cm^-2). This work fundamentally decouples material synthesis from global thermal constraints, presenting magnetic induction not merely as a heating tool, but as a novel field-matter interaction medium for the benign-by-design construction of advanced energy interfaces.