Highly Sensitive SF₆ Decomposition Byproducts Sensing Platform Based on CuO/ZnO Heterojunction Nanofibers

Hydrogen sulfide (H₂S) and sulfur dioxide (SO₂) are two typical decomposition byproducts of sulfur hexafluoride (SF₆), commonly used as an insulating medium in electrical equipment; for instance, in gas circuit breakers and gas insulated switchgears. In our work, fiber-like p-CuO/n-ZnO heterojunction gas sensing materials were successfully prepared via the electrospinning method to detect the SF₆ decomposition byproducts, H₂S and SO₂ gases. The sensing results demonstrated that p-CuO/n-ZnO nanofiber sensors have good sensing performance with respect to H₂S and SO₂. It is noteworthy that this fiber-like p-CuO/n-ZnO heterojunction sensor exhibits higher and faster response–recovery time to H₂S and SO₂. The enhanced sensor performances can probably be attributed to the sulfuration–desulfuration reaction between H₂S and the sensing materials. Moreover, the gas sensor exhibited a high response to the low exposure of H₂S and SO₂ gas (below 5 ppm). Towards the end of the paper, the gas sensing mechanism of the prepared p-CuO/n-ZnO heterojunction sensors to SO₂ and H₂S is discussed carefully. Calculations based on first principles were carried out for Cu/ZnO to construct adsorption models for the adsorption of SO₂ and H₂S gas molecules. Information on adsorption energy, density of states, energy gap values and charge density were calculated and compared to explain the gas-sensitive mechanism of ZnO on SO₂ and H₂S gases.