Work

Hydrogen Adsorption on Transition-Metal-Decorated Graphene: Thermodynamic and AIMD Insights from DFT and Post-Hartree–Fock Methods

Year: 2026

Type: article

Abstract: Hydrogen adsorption on transition-metal-decorated graphene was investigated using a finite graphene nanoflake model combined with revPBE-D4 geometry optimizations and ωB97M-V single-point energies, complemented by PNO–CCSD(T) and DLPNO–CCSD(T) benchmarks for representative systems. Particular attention was paid to the role of spin-state effects and finite-size electronic structure, which are often neglected in periodic models. Electronic-structure analysis reveals size-dependent open-shell character in graphene nanoflakes ─one larger (G) and one smaller (G2)─where G exhibits robust, where G exhibits robust multiconfigurational singlet behavior and G2 a weaker, functional-dependent tendency. CASSCF/NEVPT2 calculations support this picture and corroborate the high-spin assignments of Sc–G and Y–G. Among the metals examined, Y, Nb, and Pd exhibit strong binding to graphene (−0.67 to −1.02 eV), whereas Sc, Zr, and Ni show moderate stabilization. Hydrogen adsorption is strongly system-dependent: the first H2 adsorption is exergonic for Y, Zr, Nb, Ni, and Pd (−0.56 to −1.63 eV), while Sc becomes favorable only upon adsorption of a second H2 molecule. In contrast, additional H2 uptake is generally disfavored for Y, Nb, and Ni, and only moderately favorable for Zr (−0.32 eV) in the second adsorption step. Three representative systems (Pd, Zr, and Sc), spanning distinct bonding regimes─molecular adsorption, dissociative hydride formation, and high-spin configurations─were used to assess the methodology, with ωB97M-V//revPBE-D4 showing close agreement with coupled-cluster interaction energies within these cases. AIMD simulations on Sc–G–2H2 and Pd–G–H2 reveal distinct finite-temperature responses: desorption of one H2 molecule and metal mobility in the Sc system versus persistent H2 coordination with bond elongation in the Pd case. Overall, the results show that hydrogen adsorption on TM-decorated graphene nanoflakes depends sensitively on the interplay between metal identity, spin state, and finite-size electronic structure.

Source: The Journal of Physical Chemistry A

DOI: 10.1021/acs.jpca.5c07741

Authors: Wilmer Esteban Vallejo Narváez, Cesar Gabriel Vera de la Garza, Serguei Fomine

Institution: Universidad Nacional Autónoma de México

Language: English

Topic: Hydrogen Storage and Materials

Subfield: Materials Chemistry

Field: Materials Science

Domain: Physical Sciences

Open Access status: hybrid

Funders: Consejo Nacional de Ciencia y Tecnología, Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México

Awards: G1342883957, G6442885326, G8865347881