Sequential element control of non-precious dual atom catalysts on mesoporous carbon nanotubes for high performance lithium–oxygen batteries

Abstract

Lithium–oxygen (Li–O₂) batteries, recognized as candidates for the highest energy storage, face challenges of irreversibility and low efficiency due to insulating discharge products. Addressing these issues, our study explores innovative dual-atom catalysts (DACs) comprising non-precious metals, specifically atomically scaled nickel (Ni) and iron (Fe), positioned on defective mesopore sites of nitrogen-doped carbon nanotubes (NCNTs) to enhance battery performance. We successfully achieved the synthesis of both homogeneous (Fe–Fe-NCNTs and Ni–Ni-NCNTs) and heterogeneous (Ni–Fe-NCNTs and Fe–Ni-NCNTs) DACs on NCNTs, by varying the loading sequences and combination of Ni and Fe. Our findings demonstrate that Fe-first-loaded DACs, particularly heterogeneous Ni–Fe-NCNT variants, excelled in both NO₂⁻ mediation reactivity and catalytic activity, achieving a longer lifespan of 200 cycles and maintaining consistent ORR/OER overpotential. Insights into the mesoporous loading sites and reaction mechanisms of these DACs in Li–O₂ cells were gained through density functional theory calculations. This research paves the way for replacing costly noble metal catalysts with tailored non-noble metal combinations, potentially revolutionizing Li–O₂ cell technology and broadening applications in heterogeneous catalysis.