DFT investigation of Pt-doped CTF-1 covalent triazine frameworks for adsorption and sensing of SF6 decomposition products

Abstract

We report a computational investigation of the gas adsorption and sensing properties of pristine covalent triazine framework CTF-1 and its platinum atom (Pt)-doped counterpart towards SF6 decomposition products (i.e., H2S, SO2, SOF2, and SO2F2 gases). For this purpose, density-functional theory calculations are employed with the TPSS exchange-correlation functional (with the Grimme-D3 empirical dispersion correction) and a 6-31+G**/Lanl2DZ mixed basis set. Pt was found to interact with a nitrogen atom, distorting the planar structure. Our results reveal that the electronic bandgap of the pristine CTF-1 lowers noticeably following surface doping with a Pt atom (3.48 vs. 1.06 eV for pristine vs. Pt-doped CTF-1, respectively), enhancing the electrical conductivity of the gas sensor. In contrast to pristine CTF-1, which displays weak adsorption performance (with adsorption energies of −0.25, −0.27, −0.31, and −0.18 eV for H2S, SO2, SOF2, and SO2F2, respectively), Pt-doped CTF-1 exhibits strong interactions with the gas species (with adsorption energies of −1.93, −2.41, −6.27, and −7.98 eV for H2S, SO2, SOF2, and SO2F2, respectively) and high sensitivity in detecting the target gas species under study. Moreover, a density of states (DOS) analysis is conducted to further characterize the mechanisms involved in gas adsorption and sensing. All four degradation products decrease the bandgap of pristine CTF-1 and increase the bandgap in Pt-doped CTF-1. The latter is generally more pronounced. We conclude that Pt-doped CTF-1 could be a novel SF6 decomposition gas adsorbent and sensor and provide experimentalists with the essential physicochemical characteristics of the designed materials for future work.