Utilizing the carbon nano-belt (8-CNB) loaded late second-row transition metal (TM) single-atom catalysts for hydrogen and oxygen evolution during water electrolysis

Production of high purity of hydrogen and oxygen via water electrolysis is setback by the high overpotential associated with water splitting. In this regard, herein the use of late second-row transition metal (TM) doped carbon nano-belt (8-CNB) as single atom catalysts for water electrolysis is investigated via density functional theory (DFT) calculations. The unique unsaturated belt-shaped structure of 8-CNB introduces functional sites that are suitable for TM anchoring. As such, the designed catalysts have shown high stability. The high stability was found to originate from the chemisorption of the metals to the support, as confirmed by the quantum theory of atoms in molecules (QTAIM) analysis. Moreover, the doped structures have shown low frontier molecular orbitals gap (HOMO-LUMO E_gap) values, indicating sufficient electrical conductivities, which is desirable in water electrolysis to facilitate the transfer of electrons. Furthermore, the catalytic activity results have shown that the Ru@8-CNB and Rh@8-CNB systems are highly active towards the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Results have shown that Ru@8-CNB exhibits a low ΔG_H value of 0.12 eV towards the HER, while Rh@8-CNB revealed a low overpotential value of 0.63 V towards the OER. The proposed SACs have catalytic activities that are competitive to the highly active Pt(III) catalyst and they are advantageous in their high atom percentage efficiency as SACs.