Si-doped biomass carbon supported Fe-N-C catalyst derived from pyrolysis of iron porphyrin for oxygen reduction reaction

Abstract

With the energy crisis increasing, there is a growing focus on using renewable biomass to develop biomass carbon catalysts for the oxygen reduction reaction (ORR). This work presents a facile pre-etch strategy to prepare rice husk (RH)-derived self-doped Si carbon (RHSiC) with optimized Si content and porous structure. Subsequently, iron porphyrin (FeTPP) is loaded onto RHSiC to form the Fe-N-SiC catalyst, ensuring the stable integration of the iron-nitrogen coordination (Fe-Nx) into RHSiC, effectively anchoring a single Fe atom. The optimal Fe-N-SiC_2 catalyst, prepared through pre-etching with 10 wt% NaOH at 30℃ for 1 hour, exhibits exceptional activity in both alkaline (E1/2 = 0.876 V) and acidic (E1/2 = 0.835 V) media. Furthermore, the Fe-N-SiC_2 catalyst displays an impressive power density of 106.6 mW cm−2 and outstanding durability in the constructed Zn-air battery (ZAB). Theoretical calculations confirm that doping Si atoms into carbon support significantly enhances the adsorption of O2 molecules. Additionally, when Si atoms are located closer to the Fe-N4 active center, it becomes more favorable for the ORR reaction to occur.