Cobalt, sulfur, nitrogen co-doped carbon as highly active electrocatalysts towards oxygen reduction reaction

Rational design of efficient, cost-effective electrocatalyst towards oxygen reduction reac-tion (ORR) is of vital importance to the wide application of polymer electrolyte membrane fuel cells. In this work, a novel and simple Na2SO4-assisted pyrolysis strategy with ZIF-12 as the precursor is reported for the synthesis of cobalt, sulfur, nitrogen, co-doped carbon (termed as CoSNC-xNa2SO4-T) materials towards ORR. Different from CoNC-800 derived from pure ZIF-12, with the presence of Na2SO4, the derived CoSNC-0.5Na2SO4-800 material exhibits layered flake morphology with hierarchical meso-microporous structure. Besides, CoSNC-0.5Na2SO4-800 material shows higher content of pyridinic-N and graphitic-N, higher relative intensity of Co-Nx, higher content of carbon defect, as well as larger spe-cific surface area in comparison with CoNC-800, which results in higher activity of CoSNC-0.5Na2SO4-800. The CoSNC-0.5Na2SO4-800 material displays a half-wave potential of 0.88 V, which is superior to that of commercial Pt/C (half-wave potential being 0.86 V). Moreover, CoSNC-0.5Na2SO4-800 demonstrates a better durability compared with Pt/C. The pyrolysis temperature and the amount of Na2SO4 are found to affect the physiochemical properties and electrochemical performance of the CoSNC-XNa2SO4-T materials. This work not only provides a facile and novel synthesis approach for the preparation of highly active Co, S, N co-doped carbon materials for ORR, but also disclosing the key structure properties for enhancing the performance of these catalysts.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.