Adsorption properties of CuO/ZnO modified HfSe2 monolayer upon SF6 decomposition gases (H2S, SO2, SOF2 and SO2F2)

Abstract

In this paper, the adsorption properties of CuO-HfSe2 and ZnO-HfSe2 substrates towards SF6 decomposition gas (H2S, SO2, SOF2 and SO2F2) were analyzed based on the first-principle calculations. The optimal position of the two metal oxides doping on HfSe2 was calculated, and the binding energies of –2.530 eV and –1.906 eV ensure the stability of CuO-HfSe2 and ZnO-HfSe2 during adsorption process. The results show that, the modification of CuO and ZnO changes the band structure of the HfSe2 monolayer, and the CuO and ZnO molecules are charged with –0.0339 e and –0.0368 e, showing the potential of adsorbed gas. Compared to the pristine HfSe2 monolayer, the adsorption distances of CuO-HfSe2 and ZnO-HfSe2 to the four gases decrease from about 3.5 Å to about 2 Å, and the adsorption energies increase from about –0.35 eV to more than –2.1 eV and more than –1.1 eV, respectively. Moreover, charge deformation density, density of states, partial density of states and molecular orbital theory were explored to clarify the interaction between the gas molecules and the substrates. The results show that, CuO-HfSe2 shows better adsorption performance than ZnO-HfSe2 for H2S, SO2, SOF2 and SO2F2. For CuO-HfSe2 system, the adsorption capacity for the four gases is ranked as: H2S > SO2 > SOF2 > SO2F2; and the sort is: SO2 > SOF2 > H2S > SO2F2 for ZnO-HfSe2 system. After gas adsorption, the conductivity of the system changes to different degrees, through which the adsorption of the gas can be detected. All adsorption systems have a long recovery time, and the methods of increasing the temperature or UV irradiation are needed to excite the gas desorption process. This study provides new sensing materials for H2S, SO2, SOF2 and SO2F2.