Investigation of NO2 Adsorption on Pd-Functionalized Janus HfSeS: A First-Principles Study

In this research, the gas sensing property of a Palladium (Pd)-decorated Janus HfSeS monolayer to nitrogen dioxide (NO2) is examined by first principles density functional theory (DFT) calculations. HfSeS is a semiconducting material with a indirect bandgap of 0.744 eV which would restrict its use in gas detection; however, Pd atoms were added on the surface of HfSeS at multiple high-symmetry locations to increase conductivity. Analysis of the Adsorption Energy shows that the top site, which is S-terminal (Pd at TS SHfSe), is the most favorable site and the energy of adsorption is −2.99 eV. When interacting with NO2, however, the functionalized system of Pd-TSe displays the most pronounced response wherein the adsorption energy was −1.376 e V, a significant charge exchange of −0.270 e and a short interaction distance of 2.015 Å. The electronic studies explain the observed change in the band structure due to the adsorption of NO2 on the Pd-decorated HfSeS surface by strong electronic interactions between the gas molecule and the Pd-decorated HfSeS surface. These results demonstrate that the Pd functionalization provides an enhancement to the NO2 detection capability of the Janus HfSeS monolayer, highlighting the potential of the Janus HfSeS monolayer to be of reasonable interest as an injector gas sensing device.