The Status of Representative Anode Materials for Lithium-Ion Batteries.

Since the invention of lithium-ion batteries as a rechargeable energy storage system, it has uncommonly promoted the development of society. It has a wide variety of applications in electronic equipment, electric automobiles, hybrid vehicles, and aerospace. As an indispensable component of lithium-ion batteries, anode materials play an essential role in the electrochemical characteristics of lithium-ion batteries. In this review, we described the development from lithium-metal batteries to lithium-ion batteries in detail on the time axis as the first step; This was followed by an introduction to several commonly used anode materials, including graphite, silicon, and transition metal oxide with discussions the charge-discharge mechanism, challenges and corresponding strategies, and a collation of recent interesting work; Finally, three anode materials are summarized and prospected. Hopefully, this review can serve both the newcomers and the predecessors in the field.

Progress on the Photocatalytic Reduction Removal of Chromium Contamination.

Rapid industrialization leads to increased wastewater discharge encompassing hexavalent chromium (Cr(VI)), which leads to serious environmental problems of toxicity and potential carcinogenicity. Removal of these species is normally carried out by ion-exchange, precipitation, membrane filtration, sorption, photocatalytic reduction, etc. This review mainly focuses on the photocatalytic and photoelectrocatalytic (PEC) reduction of Cr (VI), because of their advantages over other methods such as reduced risk of secondary pollution by non-reduced Cr (VI), no sludge formation, no need for a large amount of chemical reagents, clean and easy installation. The main factors influencing the photocatalytic reduction efficiency of Cr (VI) such as catalyst activity, solution pH, Cr adsorption on the catalyst and additives, are briefly discussed. Finally, a special emphasis is provided to the photoelectrocatalytic (PEC) reduction of Cr (VI).

Enhanced Photocatalytic Activity of B, N-Codoped TiO2 by a New Molten Nitrate Process.

B, N-codoped titania mesoporous crystals were prepared by the sol-gel method followed by a molten nitrate process to modify the sample morphology. The composition, morphology and microstructure of the obtained samples were characterized by X-ray diffraction (XRD), X-ray photoemission spectroscope (XPS), Brunauer Emmett Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). Fourier Transform Infrared spectroscopy (FTIR) revealed weak complex vibrations between the Ti-O oxide species and the unsaturated sites (Ti3+) through the incorporation of hydroxyl groups, which was not observed in the bulk titania (B-N-TiO2). The photocatalytic reactivity of boron-nitrogen codoped TiO2 was examined for the removal of methylene blue (MB) under visible light irradiation. The nitrates treated B-doped TiO2 exhibited better photocatalytic activity for dye degradation than that of B-doped TiO2 and nitrates treated TiO2. The best performance was obtained in the sample treated at a calcination temperature of 550 °C.

Simultaneous Reduction of Vanadium (V) and Chromium (VI) in Wastewater by Nanosized ZnWO4 Photocatalysis.

Vanadium (V, V) and chromium (Cr, VI) are simultaneously photocatalytically reduced to less-toxic V(VI) and Cr(III) by mimetic solar light with ZnWO4 nanoparticles prepared by hydrothermal synthesis. The reduction efficiencies can reach 68.8% for V(V) and 97.3% for Cr(VI) in 3 h, respectively, which are comparable to those by microbial fuel cell technology carried out in over 10 days. The prepared ZnWO4 nanoparticles are characterized by XRD, SEM, EDS, TEM, and Uv-vis-DRS tests. Electrochemical calculation shows high acidity benefits the rapid reduction of V(V) and Cr(VI). In addition, the applied ZnWO4 nanoparticles can be recycled and reused for 5 repeated photocatalytic reduction runs. And after 5 runs, the recycled ZnWO4 nanoparticles can also present good photocatalytic activity with a reduction efficiency of about 60% for V(V) and 90% for Cr(VI). The new procedure on the simultaneous reduction of V(V) and Cr(VI) by photocatalysis may be promisingly applied in contaminated wastewaters, combining the remediation and possible V and Cr recovery.

Synthesis of Composite Titanate Photocatalyst via Molten Salt Processing and Its Enhanced Photocatalytic Properties.

Photocatalysis plays a pivotal role in environmental remediation and energy production and improving the efficiency of photocatalysts, yet enhancing its efficiency remains a challenge. Titanate has been claimed to be a very promising material amongst various photocatalysts in recent years. In this work, a novel composite photocatalyst of sodium titanate and potassium titanate was synthesized via a simple hydrothermal and molten salt calcination method. Low melting point nitrate was added in the calcination process, which helps reduce the calcination temperature. The as-prepared composite sample showed excellent photocatalytic performance compared with commercial P25 in the visible light range. According to the characterization of XRD, SEM, TEM, BET, UV-Vis, and photocatalytic property testing, the composite's photocatalytic performance results are due to the dual optimization brought about by the layered structure and composite of titanium salts forming a heterojunction. We believe that the composite has significant application potential for the use of titanate in the field of photocatalysis. Notably, this study employed well-documented synthesis methods and adhered to established protocols for experimental procedures.

Data on novel C fibers@MoSe2 nanoplates core-shell composite for highly efficient solar-driven photocatalytically degrading environmental pollutants.

The data presented in this article are related to a research article entitled 'Highly efficient solar-driven photocatalytic degradation on environmental pollutants over a novel C fibers@MoSe2 nanoplates core-shell composite' (Wang et al., 2018) [1]. In this article, we report original data on the synthesis processes optimization of the proposed composite together with its formation mechanism. The report includes the composition, microstructure and morphology of the corresponding samples, and the photocatalytic activity and stability of the optimal composite. Compared with commercially available MoSe2 powder, the reaction rate constant of the optimal composite catalyst for the degradation of methylene blue (MB) and rhodamine B (RhB) under simulated sunlight irradiation (SSI) could be increased in a factor of about 14 and 8, respectively. The data are presented in this format to allow the comparison with those from other researchers in this field, and understanding the synthesis and photocatalysis mechanism of similar catalysts.

Highly efficient solar-driven photocatalytic degradation on environmental pollutants over a novel C fibers@MoSe2 nanoplates core-shell composite.

As an important member of two-dimensional transition metal dichalcogenides, MoSe2 has a wide range of photoelectrochemical properties. However, MoSe2 alone can not directly be used as photocatalyst for its poor performance owing to the strong recombination of photogenerated electron-hole pairs. Here, we propose a novel C fibers@MoSe2 nanoplates core-shell composite, which was prepared by a facile, one-step thermal evaporation method. The composite has a remarkable feature of numerous MoSe2 thin nanoplates grown in-situ, densely and even vertically on the surface of the C fibers. Due to the effective separation of photogenerated electron-hole pairs promoted by the prompt transfer of photogenerated electrons through C fibers, compared with commercially available pure MoSe2 powder, such composite exhibits greatly improved solar-driven photocatalytic activity and high stability for the degradation of various organic/inorganic environmental pollutants including methylene blue, rhodamine B, p-chlorophenol and K2Cr2O7 aqueous solutions, showing the great potential for environmental remediation by degrading toxic industrial chemicals in waste water using sunlight. Moreover, this one-step thermal evaporation is an easy-handling, eco-friendly and low-cost synthesis method, which is suitable for large-scale production.

Positive impedance humidity sensors via single-component materials.

Resistivity-type humidity sensors have been investigated with great interest due to the increasing demands in industry, agriculture and daily life. To date, most of the available humidity sensors have been fabricated based on negative humidity impedance, in which the electrical resistance decreases as the humidity increases, and only several carbon composites have been reported to present positive humidity impedance. However, here we fabricate positive impedance humidity sensors only via single-component WO3-x crystals. The resistance of WO3-x crystal sensors in response to relative humidity could be tuned from a negative to positive one by increasing the compositional x. And it was revealed that the positive humidity impedance was driven by the defects of oxygen vacancy. This result will extend the application field of humidity sensors, because the positive humidity impedance sensors would be more energy-efficient, easier to be miniaturized and electrically safer than their negative counterparts for their lower operation voltages. And we believe that constructing vacancies in semiconducting materials is a universal way to fabricate positive impedance humidity sensors.