Metal-Coordination Effects on the Stability and ORR/OER Activity of Layered Organometallic Single-Atom Catalysts: A Theoretical Study

Pedro H. Souza; Victor Hoyos-Sinchi; Walter Orellana

paper

Metal-Coordination Effects on the Stability and ORR/OER Activity of Layered Organometallic Single-Atom Catalysts: A Theoretical Study

arXiv:2608.06309

Abstract

Organometallic layered materials have emerged as promising single-atom catalysts for oxygen reduction and evolution reactions, but their practical use has been limited by insufficient electrochemical stability. Here, we present a density functional theory study clarifying the relationship between catalytic activity and stability in organometallic single-atom catalysts with metal-N $_{4}$ (MN $_{4}$ ) and metal-O $_{4}$ (MO $_{4}$ ) coordination. We compare graphene-embedded MN $_{4}$ motif and phthalocyanine-like frameworks with MO $_{4}$ -coordination frameworks, including M $_{4}$ (OHPTP) $_{2}$ and M $_{3}$ (HHTP) $_{2}$ (M = Mn, Fe, Co, Ni, Cu, Zn). Stability is assessed by surface Pourbaix analysis, while activity is evaluated using the computational hydrogen electrode method. MN $_{4}$ systems show competitive overpotentials but suffer strong pH-dependent instability. In contrast, MO $_{4}$ frameworks exhibit enhanced robustness across wide pH ranges while maintaining good catalytic performance. A proposed stability descriptor enables direct comparison across systems, identifying MO $_{4}$ coordination structures, particularly M $_{4}$ (OHPTP) $_{2}$ (M = Zn, Co) as optimal for balancing activity and stability in practical electrocatalysis.