Se‐Vacancy Driven Enhanced Chemisorption on Bi ₂ Se ₃ /Graphene van der Waals Heterostructure: A Density Functional Study

ABSTRACT This work reports a density functional theory (DFT) study of the adsorption and desorption of hydrogen on the van der Waals (vdW) heterostructure (1QL)/Gr(ML). Three configurations are compared: pristine, single, and double Se‐vacancies. The calculations are performed along with the investigation of charge density distribution within a specific energy window. Our results indicate that hydrogen atoms chemisorb through the bond formation with the surface atoms. The adsorption energy, charge transfer, and electronic properties are analyzed to understand the interaction strength. The adsorption energies for one H atom on pristine and vdW heterostructures are –2.12 and –2.67 eV, respectively, while the system shows moderate adsorption (–1.03 eV) with moderate desorption time, indicating reversible hydrogen behavior. For multiple hydrogen adsorption (2H, 4H, 6H) on system, adsorption energy becomes progressively more negative, suggesting that the Se vacancy enhance hydrogen binding with increasing coverage. Desorption‐time calculations indicate excellent hydrogen‐sensing and recovery potential at elevated temperatures. Linear Dirac dispersion of graphene remains preserved near the Fermi level, and defected surfaces shows improved stability and reversible behavior highlighting their potential for hydrogen‐storage and catalytic applications.