Investigating the catalytic activity of transition metal/cyclo[18] carbon single atom catalysts for hydrogen evolution reaction: A DFT study

To meet the increasing demand for renewable and clean energy, there is an active search for a cost-effective, abundant, and efficient catalyst suitable for replacing platinum-based catalysts in hydrogen evolution reactions (HER). There is a rising interest in the scientific community regarding the search for suitable support for single-atom catalysts (SACs). The primary objective of SACs is to provide high catalytic activity while reducing dependence on expensive noble transition metals in energy conversion applications using electrochemistry. In the present study, we investigated the possibility of HER activity using DFT calculations for nine different transition metals (TMs) single atoms supported on cyclo[18]carbon (CY18C) nanoclusters. The stability of the designed SACs was confirmed through binding energy calculations. The calculated binding energy is in good agreement with the alterations in structural parameters, improved dipole moments, Mulliken charge transfer, and electron densities of HOMO and LUMO orbitals, as well as the analysis of interaction patterns using the QTAIM method. For Cr/CY18C, the Gibbs free energy change of H adsorption (ΔG_HER) was recorded as –0.22 eV, demonstrating good performance as an HER catalyst. The present findings will motivate experimentalists to develop CY18C-based single-atom catalysts (SACs) for HER applications, as CY18C is an experimentally synthesized material.