Adsorption and sensing SF6 decomposed gases; SO2, SO2F2, SOF2, H2S, and HF on Fe and Co decorated monolayer BC6N. First-principles study

Abstract

Partial discharges in SF₆ circuit breakers decompose SF₆ into low-fluorine gases, which react with trace moisture to form corrosive acids, degrading contacts and impairing arc quenching capacity, necessitating a 24/7 monitoring system for early detection and prevention. In this work, carbon boronitride (BC₆N) monolayer is investigated for potential application of SF₆ decomposed gases SO₂, SO₂F₂, SOF₂, H₂S, and HF through DFT calculations. Adsorption performance through adsorption energy, charge density difference, density of states, while sensitivity through band structures, work function and transport transmission and recovery through recovery time calculations are evaluated. Results show that pristine BC₆N is weakly absorbing the gas molecules, however, BC₆N decorated with Fe and Co atoms chemisorbs the gas molecules with enhanced adsorption energy -1.01 to -1.61 eV and -0.95 to -1.58 eV respectively. Diffusion energy barrier calculation confirms that Fe and Co atoms don’t make clusters. Sensitivity of Fe/BC₆N and Co/BC₆N to gas molecules respectively follows: (67.5 % and 72.9 %) for SO₂F₂> (70.8 % and 65 %) for SOF₂> (68.7 % and 62.5 %) for SO₂> (64.5 % and 57.5 %) for H₂S> (58.3 % and 50 %) for HF. Recovery time calculations results show that strongest adsorbed SO₂F₂ molecule takes 117.5 h to be desorbed at 498 K temperature, which is considerably shortened to 1.69 nanoseconds upon UV exposure. Our proposed substrates can actively adsorb, sense and instantaneously desorb the target gas molecules, proving that Fe/BC₆N and Co/BC₆N can potentially be highly sensitive and reusable gas sensors.