Two-Dimensional N,S-Codoped Carbon/Co₉S₈ Catalysts Derived from Co(OH)₂ Nanosheets for Oxygen Reduction Reaction

The development of highly active and cost-efficient electrocatalysts for the oxygen reduction reaction (ORR) is of great importance in a wide range of clean energy devices, including fuel cells and metal-air batteries. Herein, the simultaneous formation of Co₉S₈ and N,S-codoped carbon with high ORR catalytic activity was achieved in an efficient strategy with a dual templates system. First, Co(OH)₂ nanosheets and tetraethyl orthosilicate were utilized to direct the formation of two-dimensional carbon precursors, which were then dispersed into thiourea solution. After subsequent pyrolysis and template removal, N,S-codoped porous carbon-sheet-confined Co₉S₈ catalysts (Co₉S₈/NSC) were obtained. Owing to the morphological and compositional advantages as well as the synergistic effects, the resultant Co₉S₈/NSC catalysts with a modified doping level and pyrolysis degree exhibit superior ORR catalytic activity and long-term stability compared with the state-of-the-art Pt/C catalysts in alkaline media. Remarkably, the as-prepared carbon composites also reveal exceptional tolerance of methanol, indicating their potential applications in fuel cells.