Effective MOF-derived electrocatalysts based on nitrogen and different transient metal doped (M: Ni, Co, and Fe) for oxygen reduction reaction toward direct ethanol fuel cell

Abstract

Non-precious metal catalysts (NPMCs) doped with nitrogen were derived from MOFs. Appropriate ligand and framework order in the precursor ensured the presence of various nitrogenous species and high surface area in the NPC, Ni-NPC, Co-NPC, and Fe-NPC electrocatalysts. Electrochemical properties of the as-prepared electrocatalysts were examined in 0.1 M KOH solution to investigate the effects of metal and doped nitrogen on the oxygen reduction reaction (ORR). The free metal electrocatalyst (NPC) displayed poor ORR activity with an onset potential of 0.87 VRHE. The presence of nickel in the Ni-NPC catalyst could not create more active sites in comparison with the NPC catalyst, while onset potential of the Co-NPC catalyst shifted to 21 mV more positive (Compare to NPC). The investigation of doping active transient metals indicated that Fe-doping could be effective. It was because of the improved ORR activity of the Fe-NPC electrocatalysts with an onset potential of 0.99 VRHE. Furthermore, in a long-term stability test, this optimum electrocatalyst could retain more than 92% of its initial current density and experienced just 57 mV loss in its half-wave potential in an accelerated degradation test. Direct ethanol fuel cell test reveals maximum power density of 19.2 mW cm−2 at ambient temperature.