Ammonium-Salt-Assisted Post Loading: A Cost-Effective Route to High-Performance Co-N-C with Enriched Active Sites in Surface for Nitroarene Hydrogenation

Abstract

Co-N-C catalysts are promising alternatives to noble-metal systems for nitroarene hydrogenation. However, it remains challenging to develop cost-effective synthetic routes that afford high-performance Co-N-C catalysts capable of meeting the requirements of industrial applications. Herein, we present an ammonium salt-assisted post-loading strategy for constructing Co-N-C catalysts at extremely low cost, enabling efficient hydrogenation under mild conditions. Specifically, using a low-cost N-doped carbon support, Co sites are introduced by impregnation, followed by high-temperature carbonization in the presence of an ammonium salt, yielding Co/NC-AM with abundant single-atom Co (Co1) and Co nanoparticles (CoNPs). These sites work synergistically: CoNPs promote homolytic activation of H2, whereas substrates preferentially adsorb and activate on Co1 sites. More importantly, such a synthetic strategy exposes the sites on the surface of the carbon matrices, without carbon encapsulation, thereby enhancing their utilization efficiency. Consequently, Co/NC-AM delivers superior hydration performance for the hydrogenation of nitro compounds and offers excellent cost advantages, possessing the highest cost-performance ratio among all reported catalysts. This work presents a technically feasible and economically attractive route to synthesizing M-N-C catalysts, applicable not only to hydrogenation but also to other processes.