Adsorption and splitting of H₂S on 2D-ZnO_1-xN _y: First-principles analysis

We present a thorough analysis of molecular adsorption of a toxic gas, H₂S, on pristine, defective and N-substituted 2D-ZnO using first-principles simulations within density functional theory and the parameterized form of van der Waals (vdW) interaction. We find that the binding of H₂S with pristine 2D-ZnO is relatively weak (adsorption energy E_A = -29 to -36 kJ mol^-1) as it is mainly through the vdW interaction. However, substitutional nitrogen doping in 2D-ZnO leads to a drastic increase in the adsorption energy (E_A = -152 kJ mol ^-1) resulting in dissociation of H₂S molecules. This originates fundamentally from a strong covalent bonding interaction between an unpaired electron in the p-orbital of nitrogen and an electron in the s-orbital of H. While O-vacancy in 2D-ZnO has little effect on its interaction with H ₂S at lower coverages, a strong interaction at higher coverages leads to splitting of H₂S and formation of H₂ molecules. Our work shows that 2D-ZnO is a promising material to facilitate capturing of toxic H₂S from the environment and at the same time converting it to a green source of energy. This journal is