Constructing Asymmetrical Coordination Microenvironment with Phosphorus-Incorporated Nitrogen-Doped Carbon to Boost Bifunctional Oxygen Electrocatalytic Activity

Carbon-based metal-free electrocatalysts have been recognized as inexpensive alternatives to afford excellent activity in oxygen reduction/evolution reactions (ORR/OER). Nevertheless, precisely identifying the local active sites and tailoring the corresponding electronic properties to enhance the reaction kinetics remain challenging. Herein, a facile strategy to create a metal-free electrocatalyst comprised of a mesoporous nitrogen-doped carbon matrix with phosphorus incorporation (NPC) is described. The as-prepared NPC-950 electrocatalyst demonstrates superior ORR activity under alkaline and acidic conditions with half-wave potentials of 0.88 and 0.72 V, respectively, comparable to commercial Pt/C (0.85 and 0.76 V) and overwhelmingly superior to other N-doped carbon catalyst materials. In addition, a remarkable promotion of OER activity under alkaline conditions is observed. Notably, a zinc-air battery equipped with this NCP-950 electrocatalyst exhibits exceptional performance in peak power density, specific capacity, and long-term operation durability. Theoretical calculations uncover that the incorporation of phosphorus in NC material results in effective charge density redistribution, thus modulating the electronic properties of active sites to achieve optimum adsorption and desorption of ORR intermediates. The work provides a deep understanding of active sites in heteroatom-doped carbon materials and highlights the importance of the electronic properties modulation in oxygen bifunctional electrocatalytic activity. Herein, a facile strategy to access a metal-free electrocatalyst comprised of a mesoporous nitrogen-doped carbon with phosphorus incorporation is reported. It exhibits superior ORR/OER bifunctional electrocatalytic activity and demonstrates great promise in zinc-air batteries. Theoretical calculations reveal that the optimized electronic properties of NPC contribute to the exceptional electrocatalytic performance.image