Hydrogen adsorption and dissociation on transition metal anchored B ₁₂ N ₁₂ nanocages: insights from density functional theory

The growing worldwide transition to carbon-neutral energy systems requires the development of novel, efficient, and sustainable catalysts for key reactions, including hydrogen dissociation. As hydrogen is increasingly recognised as a clean and scalable energy carrier, the design of cost-effective, noble metal-free single-atom catalysts (SACs) has become a pressing priority. In this study, we employ density functional theory (DFT) to systematically explore a new class of SACs based on transition metal-anchored boron nitride nanocages (M@B12N12) for the hydrogen dissociation reaction (HDR). To better reflect real reaction environments, H₂ dissociation was studied in water using an implicit solvation model. Interaction energy (<i>E</i>_int) analyses confirm the thermodynamic stability of all designed complexes, while Co@B12N12, Ni@B12N12, Fe@B12N12, and Cr@B12N12 have been found to possess very low activation energy (<i>E</i>_a) barriers, 0.14 eV, 0.16 eV, 0.19 eV, and 0.21 eV for H₂ activation, respectively, showing the best catalytic performance. To get insights into the intrinsic activation process, we perform detailed natural bond orbital (NBO), electron density difference (EDD), and quantum theory of atoms in molecules (QTAIM) analyses. Furthermore, reduced density gradient (RDG) and non-covalent interaction (NCI) analyses reveal the presence of both weak van der Waals forces and directional covalent interactions that collectively stabilise transition states and promote efficient H-H bond cleavage. Following the multi-dimensional analysis of the electronic structure, the synergistic mechanism of charge transfer and orbital hybridization observed demonstrates that the Co@B12N12 complex exhibited high efficiency as a SAC with a minimum <i>E</i>_a value of 0.14 eV for hydrogen dissociation. The insights provide useful design guidelines for the next-generation hydrogenation catalysts, which directly leads to the establishment of hydrogen technologies that are scalable in providing clean energy solutions to the world.