Metalloporphyrin doped rice husk-based biomass porous carbon materials as high performance electrocatalyst for oxygen reduction reaction in Zn-Air battery

Rice husk (RH) is one of the most abundant biomass having a unique natural structure. Herein, the highly porous rice husk carbon material (RHC) has been prepared. After loading metal (Fe, Co, Mn, Cu) complex of tetra-phenylporphyrin (TPP) and the followed calcination, a new kind of metal-nitrogen-carbon (M-N-C) electrocatalyst (MTPP/RHC) for the oxygen reduction reaction (ORR) was obtained. It was found that all prepared catalysts showed good ORR performance and the activity follows an order of Fe > Co > Mn > Cu catalyst. The best FeTPP/RHC catalyst exhibited an ORR activity with a half-wave potential of 0.88 V (Eonset = 0.96 V) and excellent long-term stability (97% retention after 30000s). In the constructed zinc-air battery, it even showed a higher specific capacity (766 mAh/g) and superior reversibility than commercial Pt/C catalysts. This work provides a new practical protocol for ORR electrocatalysts.