Synthesis of trimetallic oxide/nitrogen-doped carbon composite using ZIF-guided combustion pyrolysis for efficient bifunctional oxygen catalysis in zinc–air batteries

Abstract

Multi-element catalysts coupled with heterogeneous atom-doped carbons have significant potential for bifunctional oxygen catalysis owing to multiple active sites and tunable electronic structures. However, their synthesis routes involve multi-step procedures, limiting efficient screening of optimal designs considering electrocatalytic performance. Herein, we present a single-step strategy for synthesizing Co/Ni/Fe trimetallic oxide (TO) catalysts within nitrogen-doped carbon (NC) networks via combustion pyrolysis of ZIF-67 metal–organic framework/NiO/Fe2O3 precursors. The ultrafast melting-recrystallization induced by a rapid heating-cooling duration (∼1.5 s) lead to uniformly mixing metal elements, enabling abundant oxygen vacancies/strong chemical bonds within the porous structure, and optimizing the energy barrier for bifunctional catalysis, while decreasing interfacial resistances. The optimized TO-NC catalyst exhibits excellent overpotential of 0.88 V, and provides outstanding power density (125 mW cm−2) and stability (>200h) to a liquid zinc–air battery, outperforming those with a Pt/C + Ir/C catalyst. This research establishes scalable yet tunable thermochemical fabrication of multi-element/carbon-based catalysts.