Showing papers by "Zhiguo Wang published in 2017"
TL;DR: This work demonstrates the successful structural engineering and simultaneous integration of trace amount Pt in SnS2 nanosheets via a facile and effective in situ cycling voltammetry activation process, leading to the efficiently synergistic HER.
Abstract: The electrocatalytic hydrogen evolution reaction (HER) has attracted increasing attention in the field of hydrogen-based economy, whereat developing cheap and efficient catalysts to reduce the use of Pt-based catalysts is highly required. Tin disulfide (SnS2) as a new rising star has exhibited intriguing properties in energy storage and conversion applications, while showing slow progress in HER due to the inherent poor activity. Herein, we demonstrate the successful structural engineering and simultaneous integration of trace amount Pt in SnS2 nanosheets via a facile and effective in situ cycling voltammetry activation process, leading to the efficiently synergistic HER. Defect-rich SnS2 nanosheets decorated with a trace amount (0.37 wt %) of Pt exhibit greatly enhanced HER activity due to the synergy between them, revealing low onset potential of 32 mV and overpotential of 117 mV at 10 mA/cm2, small Tafel slope of 69 mV/dec, and large exchange current density of 394.46 μA/cm2. Present work provides an i...
68 citations
TL;DR: In this article, a gas sensor to hydrogen sulfide (H2S) based on these porous flower-like CuO nanostructures exhibited high sensitivity, good reproducibility and long-term sensing stability.
67 citations
TL;DR: In this paper, the effects of grain boundaries (GBs) in graphene on adsorption and diffusion of sodium were investigated using first principle calculations, and it was shown that the presence of GBs in graphene enhanced the adaption of sodium.
40 citations
TL;DR: In this article, a new design methodology was proposed to improve catalytic activities of catalysts based on 2D transition metal dichalcogenides through elemental doping which induces structural transformations.
Abstract: This paper reports a new design methodology to improve catalytic activities of catalysts based on 2D transition metal dichalcogenides through elemental doping which induces structural transformations. Effects of rhenium (Re) doping on structural stability/phase transformation and catalytic activity of mono-layered trigonal prismatic (2H) MoS2 were investigated using density functional theory as one example. Results show that 2H-Mo1−x Re x S2 transforms into 1T'-Mo1−x Re x S2MoS2 as the value of x is larger than 0.4, and the transfer of the electron from Re to Mo is identified as the main reason for this structural transformation. The 1T'-Mo1−x Re x S2 shows a good catalytic activity for the hydrogen evolution reaction when 0.75 ≤ x ≤ 0.94.
26 citations
TL;DR: TheSelf-charging mechanism of SCLIBs is revealed, in which the piezoelectric potential can assist the deintercalation and intercalation proccesses at the cathode and anode upon self-charging, which may be responsible for the experimentally observed efficiency.
Abstract: Self-charging lithium ion batteries (SCLIBs) that hybridize mechanical energy harvesting and storage processes into one process can be fabricated using a piezoelectric polyvinylidene fluoride (PVDF) film as a separator in lithium ion batteries. In this paper, the deintercalation reaction at LiCoO2 and intercalation reaction at graphite were studied under an internal piezoelectric field using density functional theory. It was found that the internal piezoelectric field applied on the anode can increase intercalation energies and diffusion behavior, at the same time, and the internal piezoelectric field facilitates the deintercalation reaction at the cathode. The simulation results revealed the self-charging mechanism of SCLIBs, in which the piezoelectric potential can assist the deintercalation and intercalation proccesses at the cathode and anode upon self-charging, which may be responsible for the experimentally observed efficiency of SCLIBs.
16 citations
TL;DR: In this article, the adsorption and magnesiation behavior of Mg onto α-Sn and Mg2Sn through (100), (110) and (111) surfaces were investigated by using first-principles calculations.
Abstract: The adsorption and magnesiation behavior of Mg onto α-Sn and Mg2Sn through (100), (110) and (111) surfaces were investigated by using first-principles calculations. It was found that the Mg atom prefers to be adsorbed on the surface rather than diffuse into the sub-surface of Sn. The diffusion energy barrier is higher for Mg diffusing from the surface to the subsurface compared with the internal diffusion. Mg diffuses much faster along the direction than along the and directions. The diffusion process from the surface to the subsurface is a rate-limiting step for Mg intercalation into Sn. The surface magnesiation is also a rate-limiting step for Mg intercalation into Mg2Sn though (100) and (110) surfaces, whereas the surface magnesiation of the Mg2Sn (111) surface is easier than the (100) and (110) surfaces. Surface modification is necessary to improve the magnesiation behavior of Sn as an anode for MIBs, especially when the anode materials are reduced to the nanoscale.
15 citations
TL;DR: In this article, a new design methodology was proposed to improve the catalytic activity of catalysts based on two-dimensional transition metal dichalcogenides through a simple mechanical bending.
Abstract: In this paper, mechanisms behind enhancement of catalytic activity of MoS2 mono-layer (three atomic layers) for hydrogen evolution reaction (HER) by mechanically applying bending strain were investigated using density functional theory. Results showed that with the increase of bending strains, the Gibbs free energy for hydrogen adsorption on the MoS2 mono-layer was decreased from 0.18 to −0.04 eV and to 0.13 eV for the bend strains applied along the zigzag and armchair directions, respectively. The mechanism for the enhanced catalytic activity comes from the changes of density of electronic states near the Fermi energy level, which are induced by the changes of the Mo-S and Mo-Mo bonds upon bending. This report provides a new design methodology to improve the catalytic activity of catalysts based on two-dimensional transition metal dichalcogenides through a simple mechanical bending.
14 citations
01 Jun 2017
TL;DR: In this paper, the diffusion behavior of Li ions in Si(100) and Si(111) slabs with a piezoelectric field applied perpendicularly to the surfaces were investigated using density functional theory.
Abstract: Group IVA elements (Si, Ge and Sn) are promising candidates for the anode materials of lithium ion batteries (LIBs) due to their large theoretical specific capacities. However, serious problems of pulverization and capacity degradation resulted from the huge volume changes during charge/discharge operations hindered their successful applications as the anode materials in the LIBs. In this work, diffusion behaviors of Li ions in Si(100) and Si(111) slabs with a piezoelectric field applied perpendicularly to the surfaces were investigated using density functional theory. Results showed that the diffusivity of the Li in Si can be significantly enhanced by applying the electric field generated from the piezoelectric material. This finding can explain well the recent experimental observations in which improved electrochemical performance was obtained using Si/carbon nanotube/BaTiO3 as the anode for the LIBs. New generation of anode composite materials can be designed based on this idea and the piezoelectric material is used not only to accommodate the volume variation of active materials of Si, but also to enhance the charging rate of the LIBs.
9 citations
TL;DR: In this paper, the surface stability of LiNi0.5Mn1.5O4 (LNMO) crystallographic structures with a P4332 space group and phase transitions at the surface regions was investigated.
Abstract: First-principle calculation was employed to investigate the surface stability for (100), (110), and (111) low-index facets of LiNi0.5Mn1.5O4 (LNMO) crystallographic structures with a P4332 space group and phase transitions at the surface regions of Ni0.5Mn1.5O4. The calculated surface energies of (100) and (111) facets with Li-terminations are 1.39 and 1.40 eV, respectively, indicating that both these facets of the LNMO are stable according to the calculation results. Defect formation energies and diffusion barriers of Ni and Mn in surface facets of the Ni0.5Mn1.5O4 are much lower than those in the bulk. This suggests that the Ni and Mn ions in the surface regions of the LNMO easily occupy the tetrahedral Li-positions during delithiation process, which supports the experimental results and explains the surface structure changes of the LNMO upon delithiation.
7 citations
TL;DR: In this article, the surface atomistic structure and termination of Ti2O3 nanoparticles were analyzed using atomic-scale aberration-corrected scanning transmission electron microscopy (STEM) combined with density functional theory (DFT) calculations.
Abstract: For nanostructured particles, the faceting planes and their terminating chemical species are two critical factors that govern their chemical behavior. The surface atomistic structure and termination of Ti2O3 crystals were analyzed using atomic-scale aberration-corrected scanning transmission electron microscopy (STEM) combined with density functional theory (DFT) calculations. STEM imaging reveals that the Ti2O3 crystals are most often faceted along (001), (012), (−114), and (1–20) planes. The DFT calculation indicates that the (012) surface with TiO-termination has the lowest cleavage energy and correspondingly the lowest surface energy, indicating that (012) will be the most stable and prevalent surfaces in Ti2O3 nanocrystals. These observations provide insights for exploring the interfacial process involving Ti2O3 nanoparticles.
3 citations
Patent•
15 Dec 2017
TL;DR: In this article, the preparation of a Ce(1-x)ZrxO2 nanosheet material and a preparation method thereof is described, and the preparation method comprises the following steps: preparing a mixed solution by adopting cerium nitrate, zirconium ion modified cerium oxide material, and then sequentially adding ammonium hydroxide and hydrogen peroxide, thus obtaining sol; carrying out hydrothermal treatment.
Abstract: The invention belongs to the technical field of preparation of inorganic materials, and specifically relates to a Ce(1-x)ZrxO2 nanosheet material and a preparation method thereof. The preparation method comprises the following steps: preparing a mixed solution by adopting cerium nitrate, zirconium nitrate dihydrate and sodium nitrate; then sequentially adding ammonium hydroxide and hydrogen peroxide, thus obtaining sol; carrying out hydrothermal treatment, thus obtaining the Ce(1-x)ZrxO2 nanosheet material which is ultrathin and porous. A solid solution structure is formed by a prepared zirconium ion modified cerium oxide material, the prepared zirconium ion modified cerium oxide material is in a nanosheet morphology of which the thickness is 6 to 12nm, mesopores of which the sizes are 1.9 to 2.5nm are formed in a nanosheet, the specific surface area is greater than 180m /g, and the pore volume is greater than 0.50cm /g; Zr ions are uniformly distributed in crystal lattices of cerium dioxide, and the solid solution structure is formed; industrial large-scale production can be easily carried out, high-temperature roasting treatment is not required, the energy is saved, a surfactant or strong acid and strong base are not required, and a preparation process is environmentally friendly.