Ni/NiM2O4 (M = Mn or Fe) supported on N-doped carbon nanotubes as trifunctional electrocatalysts for ORR, OER and HER

Abstract

Rationally designed and synthesized non-noble metal-based multifunctional electrocatalysts with outstanding activity and durability for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR) are critical to the commercialization of energy-related devices. Herein, two trifunctional electrocatalysts composed of Ni–NiM₂O₄ (M = Mn or Fe) supported on N-doped carbon nanotubes (NCNT) were in situ synthesized by pyrolysis of NiMn- and NiFe-based precursors, respectively, under a NH₃/Ar atmosphere. The hybrids exhibit robust trifunctional catalytic performance for HER, OER and ORR in an alkaline electrolyte. Especially, NCNT/Ni–NiMn₂O₄ exhibits excellent performance for zinc–air batteries with a high specific capacity of 502 mA h g⁻¹ and a maximum power density of 105 mW cm⁻², comparable to that of the Pt/C-based zinc–air battery. This study provides a feasible strategy for preparing highly efficient trifunctional electrocatalysts by in situ coupling metal/metal spinel oxide composites with high conductivity nanocarbon.