Abstract
Hydrogen dissociation is a key step in almost all hydrogenation reactions; therefore, an efficient and cost-effective catalyst with a favorable band structure for this step is highly desirable. In the current work, transition metal-based C(20) (M@C(20)) complexes are designed and evaluated as single-atom catalysts (SACs) for hydrogen dissociation reaction (HDR). Interaction energy (E (int)) analysis reveals that all the M@C(20) complexes are thermodynamically stable, whereas the highest stability is observed for the Ni@C(20) complex (E (int) = -6.14 eV). Moreover, the best catalytic performance for H(2) dissociation reaction is computed for the Zn@C(20) catalyst (E (ads) = 0.53 eV) followed by Ti@C(20) (E (ads) = 0.65 eV) and Sc@C(20) (E (ads) = 0.76 eV) among all considered catalysts. QTAIM analyses reveal covalent or shared shell interactions in H(2)* + M@C(20) systems, which promote the process of H(2) dissociation over M@C(20) complexes. NBO and EDD analyses declare that transfer of charge from the metal atom to the antibonding orbital of H(2) causes dissociation of the H-H bond. Overall outcomes of this study reveal that the Zn@C(20) catalyst can act as a highly efficient, low-cost, abundant, and precious metal-free SAC to effectively catalyze HDR.