Dependence on the structure and surface polarity of ZnS photocatalytic activities of water splitting: first-principles calculations

Abstract

It has been reported that phase structure and surface polarity largely affect the photocatalytic efficiency of semiconductor nanostructures. To understand the chemical activity of ZnS at the electronic level, we investigate electron structures and carrier transportation ability for bulk intrinsic zinc blende (ZB) and wurtzite (WZ) ZnS, as well as the reaction pathway of hydrogen generation from water splitting on Zn-and S-terminated polar surfaces. The electron structure calculations prove that the WZ phase possesses a higher reducing ability than the ZB phase. The conductivity of the bulk ZB phase surpasses that of the WZ phase at or above room temperature. As the temperature increases, the asymptotic conductivity ratio of WZ/ZB is close to the Golden Ratio, 0.62. Reaction kinetics studies indicate that Zn-terminated polar surfaces are more chemically active than S-terminated polar surfaces in the reaction of hydrogen generation from water splitting. The calculation results suggest that the first H splitting from water on Zn-terminated polar surfaces can occur with ground state electronic structures, while photoassistance is necessary for the first H splitting on the S-terminated surfaces. Electronic triplet states calculations further show that Zn-terminated surfaces are more photosensitive than S-terminated surfaces.

A study on the synthesis, longitudinal optical phonon–plasmon coupling and electronic structure of Al doped ZnS nanorods

“…The energy band gap was estimated to be 2.35 eV at the high symmetry G-point in the Brillouin zone for pure ZnS. Lashgari et al 59 reported that for 3D wurtzite-ZnS, the bandgap is 2.14 eV and 2D wurtzite-ZnS has a band gap of 2.77 eV at the PBE-GGA level of theory, also Meng et al 60 reported that bulk W-ZnS has a band gap of 2.09 eV, and our obtained optical gaps are comparable with these results. At the zero position in the band structures of the compounds in Fig.…”

Effect of effective mass and spontaneous polarization on photocatalytic activity of wurtzite and zinc-blende ZnS

“…18 In addition, it has also caused more attention in photocatalysis due to the fast generation of photogenerated electron-hole pairs 19 and more negative conduction band potential. 20,21 The theoretical efficiency of photocarrier generation of ZnS is even higher than that of TiO 2 . 22 For above reasons, ZnS is regarded as a highly active photocatalyst for hydrogen generation even without cocatalyst.…”

Graphene and novel graphitic ZnO and ZnS nanofilms: the energy landscape, non-stoichiometry and water dissociation

“…In contrast, it is well known that pure DFT (LDA and GGA) underestimates the band gap of bulk ZnO and ZnS. [40][41][42][43][44] All the systems studied in this work have direct band gaps. In ZnO and ZnS, the top of the valence band is composed predominantly of anion p states, while the bottom of the conduction band is composed mostly of Zn 4s states.…”