Insight on the treatment of pig blood as biomass derived electrocatalyst precursor for high performance in the oxygen reduction reaction

Biomass derived carbon via hydrothermal carbonization are critically important for the catalysis research field requiring high activity with low cost. However, most of them present low activity due to low surface areas with large particle size originating from unnecessary compounds in raw status. Here, we report a porous carbon decorated with Fe₃C/Fe₃O₄ nanoparticles via pretreatment of pig blood (PB) by employing solvent pretreatment and pyrolyzing in regulated environment using a Fe-porphyrin-type macrocycle as catalyst precursors. Importantly, the addition of toluene to the raw form of PB as pretreatment plays a significant role in not only producing the nanoparticles with porous carbon materials but also removing impurities that deteriorate the active sites of molecular nitrogen carbon (MNC) type catalysts during high-temperature activation. Furthermore, the temperature for hydrothermal treatment and pyrolysis influences oxygen reduction reaction (ORR) performances. The highest-performing PB-derived catalyst delivered its kinetic current and the degree of degradation (after 10,000 potential cycles) were 1.57 mA/cm² (at 0.9 V) and 19 mV (half-wave potential), and those of Pt/C were 1.26 mA/cm² and 43 mV, respectively. The catalysts were prepared by applying pretreatment to the PB and characterized systematically to investigate how such pretreatment influences the physical properties and ORR performances.