First-principles investigation of Sc and Ti-decorated hBN monolayers as adsorbents and gas sensors for SF6 decomposition products

Abstract

The sulfur hexafluoride (SF₆) gas disintegrates into low fluorine gases when high-voltage and power circuits are utilized often. Therefore, timely identification and collection of the degraded gases is essential to the SF₆ electrical circuit breakers (ECBs) successful functioning. This study used density functional theory (DFT) simulations to evaluate the gas sensing and adsorption properties of the SF₆ breakdown products SO₂F₂, SOF₂, SO₂, H₂S, and HF on a Scandium (Sc) and Titanium (Ti) decorated hBN monolayer. The results showed that when exposed to gas molecules with appropriate adsorption energy, pure hBN desorption occurred quickly. Sc and Ti decoration of hBN may improve its adsorption capacity for uses in gas adsorption and sensing. The adsorption analysis of SO₂F₂, SOF₂, SO₂, H₂S, and HF adsorbed on Sc-decorated hBN monolayer revealed the corresponding adsorption energies are -1.29, -1.21, -1.15, -1.06, and -0.94 eV. However, Ti-decorated hBN exhibits gas adsorption energies of -1.51, -1.31, -1.29, -1.17, and -0.99 eV, respectively. The investigation of the gas sensing mechanism focuses on the sensing material's band structure and work functions. Although Sc has lower adsorption energies than Ti, it was demonstrated that Sc decorated hBN was even more sensitive to all gas molecules than Ti. The room-temperature release time of gas molecules may be shortened to nanoseconds by heating them to 500 K or exposing them to UV radiation at 300 K. This study provides theoretical predictions for evaluating the gas sensing capabilities of hBN monolayer decorated with Sc and Ti for detecting SF₆ breakdown products.