Dual Carbide Heterostructure Interface Mimicking Noble Metal-Like Activity for Reversible Dioxygen Catalysis in Rechargeable Air Batteries

Abstract

Recently, there has been significant interest in replacing expensive electrocatalysts with efficient bifunctional materials for facilitating dioxygen redox. Transition-metal carbides, known for their conductivity and mechanical strength, are promising toward this purpose. However, their lower activity and the resulting impact on commercial viability continue to present significant challenges. This study introduces a unique method for creating heterostructured interface comprising molybdenum carbide and vanadium carbide supported on nitrogen-doped graphene (MVC) for catalyzing dioxygen redox chemistry oxygen reduction reactions (ORR) and oxygen evolution reactions (OER) with activity comparable to noble metals. MVC exhibits performance metrics comparable to Pt in the ORR and required only half the overpotential to catalyze the OER at the desired rate compared to its individual counterparts. Improved dioxygen redox is attributed to heterostructure-assisted electron density modulation of the active redox species (required for OER and ORR) in MVC. Integration of MVC into a laboratory-level zinc–air battery prototype demonstrated almost similar round-trip efficiency compared to the benchmark Pt/C + RuO₂ electrocatalyst, indicating its potential as an inexpensive bifunctional electrocatalyst.