Wuhan University of Technology

About: Wuhan University of Technology is a education organization based out in Wuhan, China. It is known for research contribution in the topics: Microstructure & Photocatalysis. The organization has 40384 authors who have published 36724 publications receiving 575695 citations. The organization is also known as: WUT.

Layered VS2 Nanosheet‐Based Aqueous Zn Ion Battery Cathode

Abstract: DOI: 10.1002/aenm.201601920 class of materials show great potential for the insertion/extraction of multivalent ions (Zn2+, Mg2+, Al3+) owing to the characteristic of large layer spacing and high conductivity. Among all the TMDs, VS2 is a typical family member of TMDs with hexagonal system, which shows similar crystal structure to that of graphite lamellar with an interlayer spacing of 5.76 Å.[25,30] There is a vanadium layer between two sulfur layers to form a kind of sandwich structure. In VS2 crystal structure, each V atom is arranged around six S atoms and connected with S atoms with covalent bonds. The interlayer spacing of VS2 is so large that enables the convenient insertion/extraction of lithium ions (0.69 Å), sodium ions (1.02 Å), zinc ions (0.74 Å) or their solvation sheath in electrolyte. However, to the best of our knowledge, there is no report about VS2 as the electrode materials for ZIBs. Herein, the VS2 nanosheets are synthesized via a facile hydrothermal reaction (Supporting Information), which deliver a high capacity of 190.3 mA h g−1 at a current density of 0.05 A g−1 and exhibit long-term cyclic stability as the cathode for ZIBs. The electrochemical reaction mechanism of such VS2 electrodes is further investigated systematically through a series of measurements including ex situ X-ray diffraction (XRD), ex situ X-ray photoelectron spectroscopy (XPS), in situ Raman, ex situ transmission electron microscopy (TEM). A reversible insertion/extraction process can be observed from all aspects. Both the ex situ TEM and ex situ XRD results demonstrate that the interlayer space of VS2 can self adapt to the intercalation of Zn2+ with an expansion along the c-axis (only 1.73%) and a slightly shrink along the aand b-axes, which plays a key role in the realization of long-life ZIBs. All the above evidences reveal that the VS2 is a promising cathode material with high capacity and good cyclic stability for ZIBs. The crystal structure of the as-prepared VS2 is tested by XRD. All characteristic peaks are in accordance with the standard card of VS2 (JCPDS NO. 01-089-1640) (Figure 1a). The Raman spectrum of the VS2 in the range of 100–1100 cm−1 is shown in Figure 1b. Six peaks located at 140.4, 192.0, 282.0, 406.6, 687.8, and 993.2 cm−1 are observed, which correspond to the rocking and stretching vibrations of V–S bonds or their combination.[25] The morphology and microstructures of as-prepared VS2 are investigated by field emission scanning electron microscopy (SEM) and high-resolution TEM (HRTEM). As shown in Figure 1c, The VS2 flowers are assembled by nanosheets with a diameter of 5–8 μm and a thickness of 50–100 nm. The d-spacing calculated from selected area electron diffraction (SAED) patterns are 2.89 and 1.64 Å (Figure 2f), which match the d-spacing values of (002) and (110) crystal planes of VS2, respectively. TEM and corresponding HRTEM images in Figure 2e show VS2 nanosheets with a d-spacing of ≈5.76 Å, The continuous researches of energy-storage devices have gained considerable attention in our world which results from the increased development of new-type energy caused by energy crisis and environmental pollution.[1–3] In the past several decades, lithium ion batteries have been widely explored and applied to various fields as they deliver higher energy density compared to other secondary batteries.[4,5] Nevertheless, the processing cost, complicated issues of safety, the limited lithium resources as well as some environmental issues lead to an urgent challenge for exploring new energy storage system.[6,7] The rechargeable aqueous batteries, such as aqueous sodiumion batteries and aqueous Zn ion batteries (ZIBs) have received incremental attention because of cost effectiveness and material abundance.[8–16] There is interest in aqueous ZIBs due to the safety, low cost, abundance of Zn source, and utilizing divalent cations to increase charge-storage capabilities. However, existing aqueous ZIBs are far from achieving the goals of excellent performances demanded by the ever increasing energy consumption. It’s hard to find cathode materials suitable for the reversible intercalation/deintercalation of Zn ions (or their solvation sheath in electrolyte), which limits the developmen of ZIBs.[16] The previous explorations of the cathode material mostly focus on manganese dioxide (MnO2) and Prussian blue analogues, whereas, the former suffers a poor rate performance and a rapid capacity fading, while the latter delivers limited capacities (about 50 mA h g−1).[17–22] Recently, Nazar and co-workers reported a high-capacity and long-life aqueous rechargeable zinc battery, composing of a Zn0.25V2O5⋅nH2O nanobelts cathode, 1 m ZnSO4 electrolyte, and a zinc anode.[23] The work indicates that the layered structure materials show great potential for the cathode of ZIBs. During the past decades, layered transition-metal dichalcogenides (TMDs), such as MoS2, WS2, and VS2 have received significant attentions in a variety of fields for their outstanding characteristic (graphene-like layered structure, direct bandgap, and fast ion diffusion).[24–26] These properties make TMDs potential candidates for battery electrode materials. When applied as the electrode materials for lithium/sodium ion battery, some excellent studies have been reported.[27–29] Also, this

Visible Light Photocatalytic H2-Production Activity of CuS/ZnS Porous Nanosheets Based on Photoinduced Interfacial Charge Transfer

Abstract: Visible light photocatalytic H2 production through water splitting is of great importance for its potential application in converting solar energy into chemical energy. In this study, a novel visible-light-driven photocatalyst was designed based on photoinduced interfacial charge transfer (IFCT) through surface modification of ZnS porous nanosheets by CuS. CuS/ZnS porous nanosheet photocatalysts were prepared by a simple hydrothermal and cation exchange reaction between preformed ZnS(en)0.5 nanosheets and Cu(NO3)2. Even without a Pt cocatalyst, the as-prepared CuS/ZnS porous nanosheets reach a high H2-production rate of 4147 μmol h–1 g–1 at CuS loading content of 2 mol % and an apparent quantum efficiency of 20% at 420 nm. This high visible light photocatalytic H2-production activity is due to the IFCT from the valence band of ZnS to CuS, which causes the reduction of partial CuS to Cu2S and thus enhances H2-production activity. This work not only shows a possibility for substituting low-cost CuS for nobl...