Herbal residue-derived N, P co-doped porous hollow carbon spheres as high-performance electrocatalysts for oxygen reduction reaction under both alkaline and acidic conditions

Development of carbon-based oxygen reduction reaction (ORR) catalysts with performance superior to noble metals across a wide pH range has been a formidable challenge. Herein, porous hollow carbon spheres co-doped with N, P (NH 3 -NPCS-900) is directly synthesized from the herbal residues of Lasiosphaera seu Calvatia (LSC). Critically, the N content was significantly enhanced in the presence of ammonia (NH 3 ) and formed a hierarchical porous structure and a large specific surface area (984.7 m 2  g −1 ). With the synergistic effect of these contributions, the NH 3 -NPCS-900 catalyst exhibit excellent ORR catalytic activity across acidic (E 1/2  = 0.615 V) and alkaline solutions (E 1/2  = 0.862 V). Zn-air batteries with NH 3 -NPCS-900 exhibit high peak power density (188 mW cm −2 ) and better cycle durability (>180 h), showing its potential and promise in applications. This study provides valuable direction and insight into how to develop porous carbon with highly efficient ORR catalytic activity from biomass.