Nitrogen-coordinated iridium doped on blue phosphorene as a bidirectional electrocatalyst for lithium–oxygen batteries: a first-principles study

Abstract

Two-dimensional blue phosphorene (BP) has emerged as a novel and efficient substrate for single-atom catalysts (SACs), holding great promise for advancing rechargeable lithium–oxygen (Li–O₂) batteries. Using first-principles simulations, we systematically investigated BP-based SACs (TM@P, TM = Ir, Ti, and V) and their N-coordinated counterparts (TM-N3@P), focusing on their structural features, interactions with lithium oxides, catalytic energetics, and overpotentials for oxygen reduction (η_ORR) and evolution (η_OER) reactions. All structures exhibited strong binding with lithium oxides, with the LiO₂ binding energy serving as a key descriptor for both charge and discharge overpotentials. Remarkably, Ir–N3@P demonstrated optimal LiO₂ binding energy (3.18 eV) and superior catalytic performance for bidirectional redox reactions, achieving ultralow η_ORR and η_OER values of only 0.32 V and 0.26 V, respectively. Nitrogen coordination consistently outperformed P-coordination, prompting further investigation of Ir with O, S, and Se ligands. The N-coordinated Ir center, with its near-neutral charge and balanced electron-accepting/donating capability, emerged as uniquely superior. This work highlights the critical role of ligand-modulated electronic properties in designing efficient SACs for Li–O₂ batteries.