Electronic and adsorption characteristics of hydrogen cyanide (HCN) and isocyanide (HNC) on intrinsic and doped phosphorene

Density functional theory calculations are performed to investigate the electronic properties of the phosphorene that is substituted with the non-metals in different patterns and concentrations and to study the adsorption of the toxic gases, hydrogen cyanide (HCN) and isocyanides (HNC), on the intrinsic and nitrogen-doped phosphorene adsorbents. It has been established previously that the number of valence electrons in the dopant atoms considerably affects the electronic characteristics of phosphorene. Doping with B, S, Si, and other non-metals has resulted in drastic changes in the direct bandgap characteristics of the semiconductor, resulting in the conversion of the semiconductor into an indirect bandgap material (boron-doped) or metallic (Si/S doped). Of all the doped surfaces, only nitrogen-doped phosphorene shows a direct bandgap. Therefore, adsorption studies are conducted to investigate the sensitivity of the toxic gases hydrogen cyanide (HCN) and isocyanide (HNC) on intrinsic and nitrogen-doped adsorbents. The adsorption results are compared to those on graphene and doped graphene surfaces. Pure phosphorene is a good candidate for the moderate adsorption of HCN and HNC due to its low adsorption energy and charge transfer. We have also found that intrinsic phosphorene is a better adsorbent for these gases than intrinsic graphene and doped graphene. In addition, N-doped phosphorene shows moderate reactivity toward HCN and HNC gases, suggesting it may be used as a metal-free catalyst for the adsorption of these adsorbates. The 2p orbitals on the nitrogen of HCN are found to play a significant role in the strong physisorption.