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

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–O$_2$) 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 LiO$_2$ binding energy serving as a key descriptor for both charge and discharge overpotentials. Remarkably, Ir–N3@P demonstrated optimal LiO$_2$ 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. ... mehrThis work highlights the critical role of ligand-modulated electronic properties in designing efficient SACs for Li–O$_2$ batteries.