Single atom catalysts supported on cyclo[18]carbon and its allotropes (B9N9 and Al9N9) for the hydrogen evolution and oxygen evolution reactions

Abstract

The scientific community is actively searching for a cost-effective, easily available and exceptionally efficient catalyst to substitute expensive and scarce catalysts based on transition metals (TMs), in order to meet the increasing demand for renewable and clean energy resources. Recently, single-atom catalysts (SACs) are specifically engineered to achieve impressive catalytic performance while minimizing the need for expensive noble TMs in electrochemical energy conversion applications. In this study, we have studied the potential of cyclo[18]carbon (C18 nanocluster), along with its analogous structures (B9N9 and Al9N9 nanoclusters), as supports for TMs (Ni, Pd, and Pt) SACs in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The strong binding between TMs and nanoclusters was confirmed by high binding energy, structural changes, Mulliken charge transfer, induced dipole moments, and shifts in HOMO and LUMO electron density. Introduction of Ni, Pd, and Pt onto the nanoclusters decreased the HOMO-LUMO gap, indicating improved conductivity of the support. Notably, the Gibbs free energy of H adsorption (ΔGH) was measured as 0.07 eV and -0.07 eV for Pt/B9N9 and Pt/Al9N9 SACs, respectively, indicating their potential as HER catalysts. These findings serve as a compelling inspiration for experimentalists in their pursuit of designing highly efficient and cost-effective HER catalysts.