CoOx @Co-NC Catalyst with Dual Active Centers for Enhanced Oxygen Evolution: Breaking Trade-Off of Particle Size and Metal Loading.

Increasing the metal loading and downsizing the metal particle size are two effective ways to boost the electrochemical performance of catalysts. However, it is difficult to simultaneously increase the metal loading and reduce the particle size since isolated individual atoms are easy to aggregate into nanoparticles when increasing the metal loading. To tackle this contradiction, we report a bottom-up ligand-mediated strategy to facilely prepare ultrafine CoOx nanoclusters anchored on a Co-N-containing carbon matrix (CoOx @Co-NC). The co-exist of N and O atoms prevent Co atoms agglomerating into large particles and allowing the formation of ultrafine dispersed Co species with large Co loading (up to 20 wt.%). Since the relationship between ultrasmall size and large metal loading is well balanced, the CoOx nanoclusters have no inhibitory effect, but facilitate the catalytic performance of Co-N4 sites during OER process. Consequently, due to the synergistic effect of ultrafine CoOx nanoclusters and Co-N4 macrocycles, the as-synthesized CoOx @Co-NC exhibit promising OER activity (η10 =370 mV, Tafel plot=40 mV/dec), bettering than that of benchmark RuO2 (η10 =411 mV, Tafel plot=72 mV/dec). This ligand-mediated strategy to synthesize carbonaceous materials containing dual active centers with large metal loading is promising for developing active and stable catalysts for electrocatalytic applications.