Novel self-nitrogen-doped porous carbon from waste leather as highly active metal-free electrocatalyst for the ORR

In this work, the synthesis and characterization of novel metal-free electrocatalysts obtained from leather scraps is reported. The waste material has been subjected to simple thermochemical treatments (pyrolysis, chemical activation and doping), obtaining high performance electrocatalysts for the Oxygen Reduction Reaction (ORR) in KOH. The effect of pyrolysis temperature on the physicochemical properties and electrochemical performance is studied. The metal-free electrocatalysts possess mesoporous structure with high specific surface area (819-2100 m2 g−1). A higher catalytic activity has been determined for the electrocatalyst treated at 700 °C (AB7), compared to samples pyrolyzed at higher temperatures. Furthermore, AB7 delivers a higher current density compared with commercial 20% Pt/C (j = 9.0 and 4.5 mA cm−2, respectively), while its on-set potential shifts only 145 mV to more negative values. The metal-free catalysts are a promising eco-friendly and scalable alternative as cathode materials for alkaline fuel cells and other electrochemical energy devices.