Enhancing Electrocatalytic Kinetics via Synergy of Co Nanoparticles and Co/Ni–N₄–C- and N-Doped Porous Carbon

Abstract

Transition-metal species embedded in carbon have sparked intense interest in the fields of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). However, improvement of the electrocatalytic kinetics remains a challenge caused by the synergistic assembly. Here, we propose a biochemical strategy to fabricate the Co nanoparticles (NPs) and Co/Ni–N4–C co-embedded N-doped porous carbon (CoNPs&Co/Ni–N4–C@NC) catalysts via constructing the zeolitic imidazolate framework (ZIF)@yeast precursor. The rich amino groups provide the possibility for the anchorage of Co2+/Ni2+ ions as well as the construction of Co/Ni–ZIF@yeast through the yeast cell biomineralization effect. The functional design induces the formation of CoNPs and Co/Ni–N4–C sites in N-doped carbon as well as regulates the porosity for exposing such sites. Synergy of CoNPs, Co/Ni–N4–C, and porous N-doped carbon delivered excellent electrocatalytic kinetics (the ORR Tafel slope of 76.3 mV dec–1 and the OER Tafel slope of 80.4 mV dec–1) and a high voltage of 1.15 V at 10 mA cm–2 for the discharge process in zinc air batteries. It provides an effective strategy to fabricate high-performance catalysts.