Short communication: Onion skin waste-derived biocarbon as alternative non-noble metal electrocatalyst towards ORR in alkaline media

Abstract In this work a first approximation to obtain non-noble metal electrocatalysts from onion skin wastes is reported. Biocarbon were obtained at a range of 600–800 °C of pyrolysis temperature activated by chemical treatment with HNO 3 . It was observed that the pyrolysis temperature has a direct effect on the structural and textural properties, besides the morphology of the onion skin waste-derived biocarbon, which shows to have influence on the catalytic activity for the oxygen reduction reaction ORR. AOB700 was the non-noble metal electrocatalyst with the best performance for the ORR evaluated in alkaline electrolyte (0.5 mol L −1 KOH), which had the highest surface area (242 m 2 g -1 ) and a current density of −2.35 mA cm −2 with an onset potential of 0.82 V/RHE. The chemical surface composition shows that N -pyridinic, N -amine, N -quaternary and N -pyrrolic nitrogen species are present on this electrocatalysts. The use of onion skin waste as raw material in the production of non-noble metal electrocatalysts is a sustainable solution to avoid the disposal of abundant biomass residues as onion skins.