Promotion effects of Ni-doping on H2S removal and ZnO initial sulfuration over ZnO nanowire by first-principle study

H2S removal and ZnO initial sulfuration over ZnO nanowire are investigated using density functional theory (DFT) calculations, and the promotion effects of Ni-doping are discussed in detail. H2S can molecularly and dissociatively adsorb on pure and Ni-doped ZnO. Our results suggest that H2S prefers to adsorb dissociatively at Ni atom, mirrored by lower dissociated adsorption energies. For H2S removal, H2O formation is generally difficult on ZnO with a high energy barrier of approximately 2 eV. In contrast, we demonstrate that Ni could significantly promote H2O formation. The SH group at Ni site directly serves as hydrogen source for OH hydrogenation to form H2O, with much lower energy barriers of less than 1 eV. The retained S atom nearby Ni more easily penetrates toward inner sites of ZnO bulk. The present work clearly indicates that H2S removal and ZnO initial sulfuration preferentially occur in the vicinity of Ni dopant.