Scrutinization of late first-row transition metals decorated octagonal boron (B8) ring complexes as single-atom catalysts for green hydrogen and oxygen production

Hydrogen as fuel has gained large interest nowadays as a green energy source. Single-atom catalysis has emerged as a promising strategy for producing hydrogen. Herein, we investigated the late first row transition metals (TM = Co, Cu, Zn, Ni and Fe) adsorbed on eight-membered boron ring (TM@B8) as potential single-atom catalysts (SAC) towards hydrogen evolution reaction (HER) as well as oxygen evolution reaction (OER), aiming to identify less expensive electrocatalysts with high efficiency. Various properties including interaction energy (E_int), energies of frontier molecular orbitals (FMOs), natural bonding orbital (NBO) charges, total density of state (TDOS) spectra and non-covalent interaction (NCI) analyses of considered complexes are explored. These findings demonstrated that both pure TM@B8 and hydrogen-adsorbed TM@B8 complexes have both structural and electronic stability. The Co@B8 complex demonstrated a favorable Gibbs free energy of 0.16 eV toward HER under gaseous conditions. Fe@B8 showed better OER activity having overall η_OER of 1.14 eV. These outcomes show the promising potential of TM@B catalysts for both HER and OER processes.