Sensing and reversible capture of methylamine, methanethiol, and formic acid on Ti2C-based MXene monolayers: a DFT study
- 1National Graphene Research and Development Center USA
Abstract
Surface termination governs adsorption and electronic response in Ti2C MXene monolayers, but how O, F, and OH terminations shape sensing and reversible capture across distinct functional groups remains unresolved. Using dispersion-corrected first-principles DFT, we evaluated Ti2CO2, Ti2CF2, and Ti2C(OH)2 for the adsorption of methylamine (CH3NH2), methanethiol (CH3SH), and formic acid (HCOOH), selected to represent amine, thiol, and carboxyl groups, respectively. The adsorption energies ranged from −0.663 to −0.231 eV, and overall adsorption strength followed Ti2C(OH)2 > Ti2CO2 > Ti2CF2. Ti2CO2 and Ti2CF2 preferentially adsorbed CH3SH, whereas Ti2C(OH)2 preferred CH3NH2 and formed the strongest adsorption complex overall. Adsorption-energy-based molecular residence-time estimates ranged from 8.10 × 10−8 to 1.40 × 10−1 s, indicating preliminary desorption trends rather than established regeneration kinetics. Ti2CO2 remained semiconducting, with model-dependent band-gap-based electronic response estimates of 22.6–33.5% and work function shifts of −0.62 to +0.13 eV, supporting its potential for semiconductor sensing within the assumed conductivity model. Ti2C(OH)2 exhibited the strongest adsorption, particularly for CH3NH2; its subsecond residence-time estimates do not independently establish reversible capture performance. Its small, similar work function shifts of −0.05 to −0.03 eV indicated limited molecular differentiation through work function alone. Ti2CF2 exhibited the weakest adsorption and shortest residence-time estimates, while molecule-dependent work function shifts of −0.54 to +0.14 eV supported its potential for work-function-based sensing. These findings demonstrate that the strongest adsorption does not necessarily produce the most distinctive electronic response and establish distinct adsorption, preliminary desorption, and electronic-response profiles for the three Ti2C monolayers.
Related
- Tailoring the Gas Sensing Performance of ZrS2 Monolayers via Noble Metal Doping for Thermal Runaway Gas Detection in LIBs: A First-Principles Study
- Probing VOC Capture and Sensing in BN-Engineered Quasi-2D FullereneMonolayers: First-Principles Insights
- Janus XSSe (X = Sc, Ti, Zr, Nb, Pd) monolayers for toxic gas sensing: a comparative first-principles study of CH₂O, COCl₂, and O₃ adsorption.
- A reversible indole-based colorimetric chemosensor for Cu²⁺: implications for smartphone-integrated sensing, logic gate experiments, environmental and biological applications.
- Rheological Properties of Self-Assembled Monolayers Formed from Oxygen-to-Carbon-Substituted Oligo(ethylene oxide) Molecules
BibTeX
@article{qu2026sensing,
title = {{Sensing and reversible capture of methylamine, methanethiol, and formic acid on Ti2C-based MXene monolayers: a DFT study}},
author = {Michael Qu and Xuan Luo},
journal = {RSC advances},
year = {2026},
month = nov,
doi = {10.1039/d6ra07364f},
url = {https://europepmc.org/article/PMC/PMC13725747},
note = {CC BY},
}
RIS
TY - JOUR
TI - Sensing and reversible capture of methylamine, methanethiol, and formic acid on Ti2C-based MXene monolayers: a DFT study
AU - Michael Qu
AU - Xuan Luo
PY - 2026
DA - 2026/11/02
JO - RSC advances
DO - 10.1039/d6ra07364f
UR - https://europepmc.org/article/PMC/PMC13725747
AB - Surface termination governs adsorption and electronic response in Ti2C MXene monolayers, but how O, F, and OH terminations shape sensing and reversible capture across distinct functional groups remains unresolved. Using dispersion-corrected first-principles DFT, we evaluated Ti2CO2, Ti2CF2, and Ti2C(OH)2 for the adsorption of methylamine (CH3NH2), methanethiol (CH3SH), and formic acid (HCOOH), selected to represent amine, thiol, and carboxyl groups, respectively. The adsorption energies ranged from −0.663 to −0.231 eV, and overall adsorption strength followed Ti2C(OH)2 > Ti2CO2 > Ti2CF2. Ti2CO2 and Ti2CF2 preferentially adsorbed CH3SH, whereas Ti2C(OH)2 preferred CH3NH2 and formed the strongest adsorption complex overall. Adsorption-energy-based molecular residence-time estimates ranged from 8.10 × 10−8 to 1.40 × 10−1 s, indicating preliminary desorption trends rather than established regeneration kinetics. Ti2CO2 remained semiconducting, with model-dependent band-gap-based electronic response estimates of 22.6–33.5% and work function shifts of −0.62 to +0.13 eV, supporting its potential for semiconductor sensing within the assumed conductivity model. Ti2C(OH)2 exhibited the strongest adsorption, particularly for CH3NH2; its subsecond residence-time estimates do not independently establish reversible capture performance. Its small, similar work function shifts of −0.05 to −0.03 eV indicated limited molecular differentiation through work function alone. Ti2CF2 exhibited the weakest adsorption and shortest residence-time estimates, while molecule-dependent work function shifts of −0.54 to +0.14 eV supported its potential for work-function-based sensing. These findings demonstrate that the strongest adsorption does not necessarily produce the most distinctive electronic response and establish distinct adsorption, preliminary desorption, and electronic-response profiles for the three Ti2C monolayers.
SN - 2046-2069
ER -