Surface hydrogenation of oxygen terminated MXenes M2CO2 (M = Ti, V, Nb)

• Published in: Surface science 2022-03, Vol.717, p.121984, Article 121984
• Main Authors: Kayumova, Tatyana R., Kolganov, Ilay P., Myshlyavtsev, Alexander V., Stishenko, Pavel V., Fadeeva, Anastasiia I.
• Format: Article
• Language: English
• Subjects: Adsorptivity; Approximation; Density functional theory; DFT; Functional groups; Hydrogenation; Isotherms; Low temperature; Monte Carlo simulation; MXenes; Niobium; Statistical methods; Surface chemistry; Titanium; Vanadium
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2021.121984

•The potential of hydrogen pair interactions on the MXenes M2CO2 surface (M = Ti, V, Nb) is always repulsive.•Nearest-neighbour repulsions negatively correlate with the lattice parameter.•Repulsions between second-nearest neighbours is weaker than between third-nearest.•Due to lateral interactions hydrogen adlayer on considered MXenes features ordered phases with 1/3 and 2/3 ML coverage and varying thermal stability.•In atmospheric air at normal conditions it is expected that Nb2CO2 has near-zero hydrogen coverage, while on V2CO2 and Ti2CO2 hydrogen adlayer should form ordered phase with 1/3 ML coverage. We have investigated reduction of MXenes M2CO2 (M = Ti, V, Nb) surface by hydrogen using density functional theory and statistical physics methods. We have approximated lateral interactions between adsorbed hydrogen with simple pairwise potential. We have confirmed model stability via cross-validation. Adsorption isotherms are calculated using Metropolis Monte Carlo method. We have built analytical Langmuir-like approximation of calculated isotherms. Ordered phases with 1/3 and 2/3 ML coverage are visually observed at low temperatures. At temperatures above 300 K no obvious plateau is observed, and intermediate phases does not exist. We compared adsorptive properties of MXenes at the same external conditions. [Display omitted]