Highly efficient lanthanum- and actinium-doped B6/B8 complexes as single-atom catalysts toward superior hydrogen evolution reaction: a DFT perspective

Context: Rapid escalating energy demand and the significant environmental impact of conventional energy sources has intensified the search for sustainable alternatives. Hydrogen evolution reaction (HER) stands out as a promising green energy solution; however, its advancement is restricted by higher kinetics and limited thermal feasibility, necessitating the development of highly active catalytic sites. Although d-block transition metals dominate current HER catalysis research, this study explores for the first time, potential of f-block elements such as lanthanum (La)- and actinium (Ac)-doped boron nano-rings (B6 and B8) as single-atom catalysts (SACs) for HER applications. Method: The catalytic performance of the designed SACs is systematically investigated using density functional theory (DFT) calculations. The PBE0 functional with the Pople 6–31 + G(d,p) basis set is employed to describe the structural and electronic properties of all complexes. Adsorption energy calculations revealed values ranging from − 4.82 to − 14.66 kcal/mol, indicating remarkable thermal stability of the newly proposed SACs. Natural bond orbital (NBO) analysis demonstrated significant charge transfer from the incorporated La and Ac atoms to the boron nano-rings, confirming strong transition metal-support interactions. Furthermore, a substantial change in the HOMO–LUMO energy gap of B6 and B8 rings upon doping highlighted a pronounced modulation of their electronic and conductive characteristics. Notably, the Gibbs free energy change associated with hydrogen adsorption on the M-B8 (M = La and Ac) complex in gas phase (0.34 and − 0.34 eV) identified as excellent single-atom catalyst candidates for the hydrogen evolution reaction. This study sets a new benchmark in catalyst designing by combining thermal stability and optimal energetics, which could revolutionize hydrogen evolution techniques for clean energy applications.