Adsorption behaviors of hydrogen sulphide on Au(110) nanoslit array surfaces using molecular dynamics simulations

The adsorption behaviour of gas molecules on detector surfaces has a profound influence on the sensitivity of the detector. For this reason, this study used molecular dynamics simulation to explore the dynamic adsorption behaviour of hydrogen sulphide (H2S) molecules on various types of Au surfaces, including a planar Au(110) structure and three types of slit array structures. The influence of system temperature, adsorbate concentration and the slit width of nanoarrays on diffusivity, average adsorption energy and static adsorption amount were systematically examined. Simulation results indicate that the self-diffusivity of the adsorbate molecules increases with temperature but decreases with adsorbate concentration. At low concentrations (similar to 3mol/L), each type of Au(110) surface structure shows good capacity to adsorb all H2S molecules. With increasing concentration at 6.5mol/L, the high concentration leads to adsorption saturation and many free H2S molecules in the planar Au(110) structure. Moreover, desorption also begins to appear on the planar structures at a temperature of 300K (at 6.5mol/L). The simulation results indicate that the columnar array structures with a slit width 5.76 angstrom allow molecules to swiftly spread into the slits and provide more stable adsorption sites (i.e. with a higher adsorption energy), which can effectively address the issues of high-temperature desorption and adsorption saturation. Particularly at low temperatures (100K), slit structures presented a level of static adsorption of H2S that was 30% to 35 higher than that of planar structures.