Vacancy-Controlled Stabilization and Reactivity of Single Metal Atoms on Titanium Nitride and Titanium Oxynitride
Year: 2026
Type: preprint
Abstract: Titanium nitride (TiN) and titanium oxynitride (TiON) are attractive conductive supports for single-atom electrocatalysts, but the role of surface vacancies in balancing metal stabilization and catalytic reactivity remains unclear. Here, we used density functional theory to screen the formation of Ag, Au, Co, Cu, Ir, Ni, Pd, Pt, Rh, and Ru single atoms on pristine and vacancy-containing TiN and TiON surfaces, and their reactivity toward the hydrogen evolution reaction (HER). Vacancy formation generally strengthens single-atom anchoring, but the corresponding changes in hydrogen adsorption are strongly metal- and defect-dependent, showing that a stronger metal–support interaction does not necessarily imply improved HER activity. Combining hydrogen adsorption thermodynamics with electrochemical dissolution stability identifies Pd atoms trapped in Ti vacancies (VTi) as the most promising candidates. Importantly, Pd@VTi shows nearly identical hydrogen adsorption energetics and dissolution potentials above 0 V vs. SHE for TiN and both investigated TiON configurations, indicating remarkable insensitivity to the local O/N arrangement. Electronic-structure analysis, ab initio molecular dynamics, and surface Pourbaix calculations further support the viability of these configurations. These results highlight cation-vacancy-confined Pd as a robust HER motif on compositionally variable Ti(O)N supports.
Source: ChemRxiv
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: green
Award: G7844472628
OpenAlex ID: W7212230487