abstract
Oxycarbide MXenes are two-dimensional transition metal carbides with subsurface oxygen content within their carbon layers. Substitutional oxygen atoms are thermodynamically very stable, impose virtually no lattice strain on their surroundings, and do not change the metallic behaviour of Ti 3 C 2 , making them very difficult to detect experimentally. Here, water is suggested as a probe to identify subsurface oxygen atoms on the H 2-exposed and heat pre-treated Ti 3 C 2 MXene. Independently of the oxygen concentration, density functional theory calculations show that water can adsorb near subsurface oxygen atoms as well as on stoichiometric Ti 3 C 2 regions of the material and is deemed appropriate for identifying substitutional oxygen defects on Ti 3 C 2 through frequency analysis. The calculated stretching mode of water increases by at least 67 cm-1 in the presence of subsurface oxygen, allowing the experimental detection of this defect, even at the lowest concentration considered, i.e., a replacement of 3 % of carbon by oxygen atoms.
keywords
ELECTRONIC-PROPERTIES; STABILITY; DEFECTS; TI3C2
subject category
Chemistry
authors
Gouveia, JD; Gomes, JRB
our authors
José Daniel Lago da Silva Neves Gouveia
Assistant Researcher
José R. B. Gomes
Principal ResearcherProjects
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
MXenes catalysts for the water gas shift reaction (ForTheShift)
Collaboratory for Emerging Technologies, CoLab (EMERGING TECHNOLOGIES)
acknowledgements
This work was developed within the scope of the projects CICECO- Aveiro Institute of Materials, with refs. UIDB/50011/2020, UIDP/50011/2020 and LA/P/0006/2020, and ForTheShift, with ref. 2022.02949.PTDC, financed by national funds through the FCT/MEC (PIDDAC) . We are also thankful to FCT I.P. for the computational resources granted in the framework of project Ref. 2022.15802.CPCA.A2 by the FCT/CPCA/2022/01 Call for Advanced Computing Projects. JDG thanks the Portuguese Foundation for Science and Technology (FCT) through the grants with Refs. 2022.00719.CEECIND and 2023.06511. CEECIND, in the scope of the Individual Calls to Scientific Employment Stimulus - 5th and 6th Editions.