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 (Co_<i>x</i>Fe_1-<i>x</i>NCN) nanoparticles as efficient OER precatalysts with stable overpotential for at least 290 h. Advanced structural characterizations disclosed the presence of abundant structural defects in low-crystalline (LC) Co_<i>x</i>Fe_1-<i>x</i>NCN. <i>Operando</i> X-ray absorption spectroscopy and X-ray diffraction studies revealed that these intrinsic structural defects could accelerate the irreversible surface reconstruction in LC-Co_<i>x</i>Fe_1-<i>x</i>NCN. This promoted the generation of high-valent metal oxyhydroxides as the real active OER phases, resulting in a lower overpotential compared to high-crystalline Co_<i>x</i>Fe_1-<i>x</i>NCN. The present study highlights the introduction of structural defects as an effective approach for the rational design of efficient OER electrocatalysts.