Accelerating Surface Reconstruction in Cobalt Carbodiimides through Structural Defects for Enhanced Oxygen Evolution

The oxygen evolution reaction (OER) is a vital bottleneck for the conversion of water and clean energy into chemical fuels through electrocatalysis. In-depth insights into the surface structural evolution of real active species on catalysts during the OER process are of great significance for knowledge-driven catalyst design. Herein, we developed iron-doped cobalt carbodiimide (CoxFe1−xNCN) nanoparticles as efficient OER pre-catalysts with stable overpotential for at least 290 hours. Advanced structural characterizations disclosed the presence of abundant structural defects in low-crystalline (LC) CoxFe1−xNCN. Operando X-ray absorption spectroscopy and X-ray diffraction studies revealed that these intrinsic structural defects could accelerate the irreversible surface reconstruction in LC-CoxFe1−xNCN. This promoted the generation of high-valent metal oxyhydroxides as the real active OER phases, resulting in a lower overpotential compared to high-crystalline CoxFe1−xNCN. The present study highlighted the introduction of structural defects as an effective approach for the rational design of efficient OER electrocatalysts.