Algae biochar (ABC), coconut shell biochar (CSBC), and coconut coat biochar (CCBC) were prepared by wet pyrolysis in a phosphoric acid solvent under normal pressure.

The development of highly active and low-cost catalysts for use in oxygen reduction reaction (ORR) is crucial to many advanced and eco-friendly energy techniques. N-doped carbons are promising ORR catalysts. However, their performance is still limited. In this work, a zinc-mediated template synthesis strategy for the development of a highly active ORR catalyst with hierarchical porous structures was presented. The optimal catalyst exhibited high ORR performance in a 0.1 M KOH solution, with a half-wave potential of 0.89 V vs. RHE. Additionally, the catalyst exhibited excellent methanol tolerance and stability. After a 20,000 s continuous operation, no obvious performance decay was observed. When used as the air–electrode catalyst in a zinc–air battery (ZAB), it delivered an outstanding discharging performance, with peak power density and specific capacity as high as 196.3 mW cm⁻² and 811.5 mAh g_Zn⁻¹, respectively. Its high performance and stability endow it with potential in practical and commercial applications as a highly active ORR catalyst. Additionally, it is believed that the presented strategy can be applied to the rational design and fabrication of highly active and stable ORR catalysts for use in eco-friendly and future-oriented energy techniques.