Highly Efficient Oxygen Reduction Electrocatalysts From Biomass‐Derived Porous Carbon for Metal Fuel Cells

Biomass carbon has emerged as a particularly promising candidate for nonprecious metal oxygen reduction catalysts, owing to its advantages as a renewable precursor and its relatively low cost. In this study, a highly active oxygen reduction catalyst (denoted as MN/BSC) based on nonprecious metal heteroatom‐doped carbon derived from biomass was prepared using a synergistic modification method involving ball milling and molten salts. This process yielded co‐doped MN/BSC catalysts with surface areas reaching up to 952 m 2 g −1 and total porosities of 0.725 cm 3 g −1 . The half‐wave potential of MN/BSC (0.929 V vs. RHE) is comparable to that of Pt/C, indicating its significant catalytic performance for oxygen reduction. The discharge performance of the self‐assembled Mg‐O 2 cell also outperformed Pt/C in all aspects. The high activity can be attributed to the synergistic pretreatment effect of ball milling and molten salts, which led to the formation of numerous defects in the carbon matrix. This synergy increases the effective active area involved in catalysis. Furthermore, the low‐melting salts act as templating and pore‐forming agents, which facilitate the dispersive doping of Fe and N, thereby increasing the number of active sites. Given these results, waste‐derived biomass carbon catalysts show considerable promise for use in metal fuel cells and electrocatalytic applications.