First principles electronic transport study of triacetone triperoxide adsorbed on Ti₃C₂O₂ and Ti₃C₂F₂ MXene...

Triacetone triperoxide (TATP) is a highly volatile and extremely dangerous peroxide-based explosive synthesized from readily accessible precursor chemicals. Due to its non-nitro composition, TATP evades most conventional field-detection systems. In this work, we investigate the potential of Ti₃C₂O₂ and Ti₃C₂F₂ MXene monolayers as portable, low-power sensing platforms for TATP vapor detection using density functional theory (DFT) coupled with non-equilibrium Green's function (NEGF) transport calculations. Three adsorption configurations (parallel and two orthogonal orientations) were systematically examined. TATP is adsorbed onto the surfaces of both MXenes via a multi-point hydrogen-bonding mechanism. This interaction yields net adsorption energies of -  0.45 eV and - 0.37 eV for Ti₃C₂O₂ and Ti₃C₂F₂, respectively. Density-of-states (DOS) and eigenstate analyses reveal HOMO-level pinning near the Fermi energy on Ti₃C₂O₂, enabling detectable current modulation at low bias. Transport simulations yield currents on the order of 10 µA at 0.1 V, at which relative current changes are measurable and amount to 3.7% for Ti₃C₂F₂ and 1% for Ti₃C₂O₂. The involvement of TATP's HOMO in the transport window for Ti₃C₂O₂ at elevated bias provides an additional sensing mechanism. Our findings suggest that both Ti₃C₂O₂ and Ti₃C₂F₂ MXenes are promising building blocks for portable, resistive TATP detectors.