H.-Y. He

Bio: H.-Y. He is an academic researcher from Shaanxi University of Science and Technology. The author has contributed to research in topics: Graphene & Photocatalysis. The author has an hindex of 10, co-authored 28 publications receiving 361 citations.

Sm-doping effect on optical and electrical properties of ZnO films

Abstract: A series of ZnO: Sm films with Sm content of 0–1.0 at.% were deposited by a chemical solution deposition. The deposited films were characterized by X-ray diffraction, field emission scanning electron microscopy, UV–Vis and luminescent spectrophotometry, and electrical resistance measurement. The experiments revealed that the Sm doping first increased and then decreased the optical transmittance, band gap, and n-type conductivity with increasing Sm content. The film with the Sm content of 0.75 at.% showed optimal optical and electrical properties. The maximal band gap widening was about 0.19 eV. The resistance decrease of ~20 times was observed. The photoluminescence measurement indicated that the films showed a strong near band gap emission and a blue-green emission related to intrinsic defect. The refractive index, extinction coefficient, and dielectric constant of the films were calculated with the transmittance and reflectance spectra.

La-doping content effect on the optical and electrical properties of La-doped ZnO thin films

Abstract: La-doped ZnO films with a series of La content were deposited by a chemical solution deposition and characterized by X-ray diffraction, field emission scanning electron microscopy, X-ray energy dispersion spectrometry, ultraviolet–visible and luminescent spectrophotometries, and electrical resistance measurement. The transmittance and electrical conductivity of the films increased and then decreased with increasing La content. The film with actual La content of 0.14 at.% showed a lowest optical absorbance, a widest bandgap of 4.08 eV, and a minimal resistance of 3.3 × 10−1 Ω cm. The films showed a strong near band gap emission and some weak emissions related to intrinsic defects, implying near perfect crystal structure. The refractive index, extinction coefficient, optical conductivity, dielectric constant of the films were calculated with the transmittance and reflectance spectra.

TiO2: Si nanotube/1T-MoSe2 nanosheet hybrids with highly efficient hydrogen evolution catalytic activity.

Abstract: Transition metal dichalcogenides exhibit an excellent catalytic activity for hydrogen evolution reaction and continue to attract many studies. Some heterojunctions are also used to enhance the catalytic activity. In this work, the TiO2 nanotubes/MoSe2 and Si-doped TiO2 NTs/MoSe2 hybrids were synthesized. The MoSe2 in the hybrids exhibited nanosheet morphology and metallic (1T) structure with high conductivity and catalytic activity for hydrogen evolution reaction. Moreover, MoSe2 decoration provided high light absorbance for the hybrids and highly efficient interface-induced effect at the heterojunction. Furthermore, the Si-doping increased specific surface area and hydrophilicity. Thus, the Si-doped TiO2 NTs/MoSe2 hybrids showed remarkably greater photocatalytic and electrocatalytic activities than the nanotubes.

Janus Monolayer Transition Metal Dichalcogenides

Abstract: A novel crystal configuration of sandwiched S-Mo-Se structure (Janus SMoSe) at the monolayer limit has been synthesized and carefully characterized in this work. By controlled sulfurization of monolayer MoSe2 the top layer of selenium atoms are substituted by sulfur atoms while the bottom selenium layer remains intact. The peculiar structure of this new material is systematically investigated by Raman, photoluminescence and X-ray photoelectron spectroscopy and confirmed by transmission-electron microscopy and time-of-flight secondary ion mass spectrometry. Density-functional theory calculations are performed to better understand the Raman vibration modes and electronic structures of the Janus SMoSe monolayer, which are found to correlate well with corresponding experimental results. Finally, high basal plane hydrogen evolution reaction (HER) activity is discovered for the Janus monolayer and DFT calculation implies that the activity originates from the synergistic effect of the intrinsic defects and structural strain inherent in the Janus structure.

Synthesis and applications of nano-TiO 2 : a review

Abstract: TiO2-based nanomaterials have attracted prodigious attention as a photocatalysts in numerous fields of applications. In this thematic issue, the mechanism behind the photocatalytic activity of nano-TiO2 as well as the critical properties have been reviewed in details. The synthesis routes and the variables that affect the size and crystallinity of nano-TiO2 have also been discussed in detail. Moreover, a newly emerged class of color TiO2, TiO2 in aerogel form, nanotubes form, doped and undoped form, and other forms of TiO2 have been discussed in details. Photocatalytic and photovoltaic applications and the type of nano-TiO2 that is more suitable for these applications have been discussed in this review.