Sulfur-Defect-Induced TiS1.94 as a High-Capacity and Long-Life Anode Material for Zinc-Ion Batteries.

Aqueous zinc-ion batteries (ZIBs) are competitive among the elective candidates for electrochemical energy storage systems, but the intrinsic drawbacks of zinc metal anodes such as dendrites and corrosion severely hinder their large-scale application. Developing alternative anode materials capable of high reversibility and stability for storing Zn2+ ions is a feasible approach to circumvent the challenge. Herein, a sulfur-defect-induced TiS1.94 (D-TiS1.94) as a promising intercalation anode material for ZIBs is designed. The abundant Zn2+-storage active sites and lower Zn2+ migration barrier induced by sulfur defects endow D-TiS1.94 with a high capacity for Zn2+-storage (219.1 mA h g-1 at 0.05 A g-1) and outstanding rate capability (107.3 mA h g-1 at 5 A g-1). In addition, a slight volume change of 8.1% is identified upon Zn2+ storage, which favors a prolonged cycling life (50.3% capacity remaining in 1500 cycles). More significantly, the D-TiS1.94||ZnxMnO2 full battery demonstrates a high discharge capacity of 155.7 mA h g-1 with a capacity retention of 59.8% in 400 cycles. It has been estimated that the high-capacity, low-operation voltage, and long-life D-TiS1.94 can be a promising component of the ZIB anode material family, and the strategy proposed in this work will provide guidance to the defect engineering of high-performance electrode materials toward energy storage applications.

Multifunctional droplet handling on surface-charge-graphic-decorated porous papers.

Developing a fluidic platform that combines high-throughput with reconfigurability is essential for a wide range of cutting-edge applications, but achieving both capabilities simultaneously remains a significant challenge. Herein, we propose a novel and unique method for droplet manipulation via drawing surface charge graphics on electrode-free papers in a contactless way. We find that opposite charge graphics can be written and retained on the surface layer of porous insulating paper by a controlled charge depositing method. The retained charge graphics result in high-resolution patterning of electrostatic potential wells (EPWs) on the hydrophobic porous surface, allowing for digital and high-throughput droplet handling. Since the charge graphics can be written/projected dynamically and simultaneously in large areas, allowing for on-demand and real-time reconfiguration of EPWs, we are able to develop a charge-graphic fluidic platform with both high reconfigurability and high throughput. The advantages and application potential of the platform have been demonstrated in chemical detection and dynamically controllable fluidic networks.

δ-VOPO4 as a high-voltage cathode material for aqueous zinc-ion batteries.

Aqueous zinc-ion batteries (AZIBs) with excellent safety, low-cost and environmental friendliness have great application potential in large-scale energy storage systems and thus have received extensive research interest. Layered oxovanadium phosphate dihydrate (VOPO4·2H2O) is an appealing cathode for AZIBs due to the unique layered framework and desirable discharge plateau, but bottlenecked by low operation voltage and unstable cycling. Herein, we propose delta-oxovanadium phosphate (δ-VOPO4) without conventional pre-embedding of metal elements or organics into the structure and paired it into AZIBs for the first time. Consequently, superior to the layered counterpart, δ-VOPO4 exhibits better performance with a prominent discharge voltage of 1.46 V and a higher specific capacity of 122.6 mA h g-1 at 1C (1C = 330 mA g-1), as well as an impressive capacity retention of 90.88 mA h g-1 after 1000 cycles under 10C. By investigation of structure resolution and theoretical calculation, this work well elucidates the structure-function relationship in vanadyl phosphates, offering more chances for exploration of new cathode materials to construct high performance AZIBs.

Ordered porous nitrogen-vacancy carbon nitride for efficient visible-light hydrogen evolution.

Photocatalytic H2 evolution is a promising technology which could be instrumental in producing clean hydrogen energy. In regard to the photocatalyst, its band structure, morphology and light utilization have a significant influence on the H2 evolution rate and stability. Herein, a three-dimensional ordered macroporous nitrogen-vacancy carbon nitride (3DOM V-CN) photocatalyst was developed by combining vacancies with 3DOM structure for visible-light photocatalytic H2 evolution. This strategy preserved the structural properties of 3DOM to improve the light utilization and the specific surface area of the photocatalysts. Moreover, constructing suitable vacancies could trap electrons to facilitate the separation of photogenerated carriers, and extend the light absorption region of the photocatalysts by adjusting band structure, thus improving photocatalytic activity. Compared with CN (0.3 mmol h-1 g-1), 3DOM V-CN demonstrated a superior photocatalytic H2 evolution rate of 2.3 mmol h-1 g-1 (λ ≥ 420 nm) while possessing excellent stability. This work provides an effective and low-cost strategy for the design of the photocatalysts with high activity and stability by simultaneously tuning the band structure and morphology.

Synthesis of Sulfur-Doped 2D Graphitic Carbon Nitride Nanosheets for Efficient Photocatalytic Degradation of Phenol and Hydrogen Evolution.

Sulfur-doped two-dimensional (2D) graphitic carbon nitride nanosheets (2D-SCN) with efficient photocatalytic activity were synthesized via (1) polycondensation of thiourea to form bulk sulfur-doped graphitic carbon nitride (SCN) and (2) followed by thermal oxidative treatment of the prepared SCN via an etching strategy to form 2D-SCN. Sulfur was doped in situ into SCN by using thiourea as the precursor, and the 2D nanosheet structure was obtained during the thermal oxidative etching process. The structural, morphological, and optical properties of the 2D-SCN sample were investigated in detail. Herein, it is shown that the thermal oxidative etching treatment and sulfur doping induced a 2D nanosheet structure (2D-SCN-3h) with a thickness of about 4.0 nm and exposure of more sulfur elements on the surface. The surface area increased from 16.6 m2/g for SCN to 226.9 m2/g. Compared to bulk SCN, a blue shift of the absorption peaks was observed for the obtained 2D-SCN-3h photocatalyst, and the absorption intensity was higher than that of the sulfur-free counterpart (2D-CN). The successful in situ doping of S element into SCN or 2D-SCN-3h samples is beneficial to the introduction of surface N defects and O species. 2D-SCN-3h indicated higher efficiency in photogenerated charge carrier separation and showed the highest reductive activity in photocatalytic splitting of water at a rate of 127.4 µmol/h under simulated solar light irradiation, which was 250 times and 3 times higher than that of SCN and 2D-CN photocatalysts, respectively. The apparent quantum efficiency was estimated to be 8.35% at 420 nm irradiation. The S-C-N bond formed by sulfur doping was beneficial to the charge-transfer process, and this led to higher photocatalytic activity according to partial density of state analysis computed by first-principles methods.

Rapid mineralization of methyl orange by nanocrystalline-assembled mesoporous Cu2O microspheres.

In this study, nanocrystalline-assembled mesoporous Cu2O microspheres (MCMs) with enhanced visible-light driven photocatalytic activity were synthesized by a facile one-step hydrothermal method. MCMs exhibit excellent visible-light driven photocatalytic activity with 85% removal of methyl orange (MO) (60% removal of total organic carbon (TOC)) in 40 min. The excellent photocatalytic performance is dependent on the specific morphology and excellent visible-light absorption ability. Interestingly, MCMs can efficiently remove MO with or without light. The amount and categories of active species were determined by electron paramagnetic resonance and photoluminance (PL). Reactive oxygen species (ROS) (mainly ·[Formula: see text] and H2O2) and Cu (I) radicals are important in fading and further mineralization of MO. With the assistance of gas chromatography-mass spectrometer , TOC and x-ray photoelectron spectroscopy, the degradation pathways in light and dark conditions were analyzed. It has been proven that MO could be efficiently mineralized by ROS generated in light, while reaction in dark condition was more likely to be an efficient fading process.

Voids padding induced further enhancement in photocatalytic performance of porous graphene-like carbon nitride.

Design of 2-Dimensional nanostructured photocatalyst is an effective way to improve the photocatalytic activity of its bulk counterpart. However, the remaining (or newborn) drawbacks, such as enlarged band gap and the surface recombination of photogenerated charge carries, extremely limited the practical application of nanosheeted photocatalysts in solar energy conversion. In this study, we demonstrated that the voids padding with NH4Cl can eliminate part of quantum size effect to reduce the band gap of nanosheeted carbon nitride. In addition, the padded NH4Cl can create conjugate center and interface electric field in nanosheeted carbon nitride, and therefore to inhibit the surface recombination of photogenerated charge carries. This work not only provides a facile strategy to eliminate the drawbacks of nanosheeted carbon nitride, but also paves a new way to further improve the photocatalytic activity of other nano-sheeted materials.

Reduction of nitrate by NaY zeolite supported Fe, Cu/Fe and Mn/Fe nanoparticles.

Nano particles Fe, Cu/Fe and Mn/Fe supported on NaY zeolite (F@Y, CF@Y, and MF@Y) were prepared by two-step processes consisting of ion exchange and liquid-phase reduction. The characterization by XRD, SEM-EDX and BET-N2 adsorption demonstrated that Fe, Cu/Fe and Mn/Fe nano particles were successfully loaded onto NaY zeolite and exhibited larger BET surface area compared to nano-Fe0 (nZVI). Laboratory experiments showed that nitrate removal by metals@Y in unbuffered conditions reached nearly 100% at a dosage of 4g/L after 6h of reaction. Moreover, the nitrate removal was not sensitive to the initial solution pH. Even at a high pH of 9.0, metals@Y exhibited nitrate reduction above 94%. CF@Y demonstrated high N2 selectivity, due to the high content of Cu (20wt%) and Fe (41wt%) in CF@Y and the highly active metallic sites on its surface with positive charge. Kinetic data showed a good fit to a first-order kinetic model during early reaction times. A close fit to both a second-order and an nth-order kinetic model was shown for the whole of the reaction period. The data suggest that both liquid phase mass transfer and the intrinsic reaction rate control the process of nitrate reduction by metals@Y.

Enhanced coagulation with in situ manganese dioxide on removal of humic acid in micro-polluted water.

The morphology and surface characteristics of manganese dioxide (MnO2) formed in situ, which was prepared through the oxidation of MnSO4using KMnO4, were studied. The effects of factors including the form of MnO2, dosage, pH, dosing sequence of in situ MnO2on the enhanced coagulation were systematically evaluated. The results of analysis by the UV254 and permanganate index CODMn methods indicated that humic acid removal increased from 9.2 and 2.5% to 55.0 and 38.9%, when 10 mg/L of the in situ MnO2 was added in the presence of 2 mg/L of polyaluminum sulfate. The studies of orthogonal experiment revealed that coagulation was most affected by the pH, whereas the dosage of in situ MnO2and slow stirring duration exhibited a weaker effect. At a pH value of 4.0, in situ MnO2dosage of 10 mg/L, slow stir over 40 min, and the total solids content was 20 mg/L, the humic acid removal by UV254 and CODMn methods reached 71.2 and 61.2%. These results indicated that the presence of in situ MnO2enhanced the coagulation and removal of humic acid from water.

Hydrothermal synthesis and photoluminescent properties of rod-shape assemblies of LaBO3:Eu3+ nanocrystals.

Uniform and assembled LaBO3 nanocrystals have been successfully synthesized via a facile hydrothermal method. These assemblies exhibit a rod-shape morphology and each of them consists of small LaBO3 nanocrystals which are tightly attached together. The phase, surface and morphology of these assemblies have been characterized. A possible assembly mechanism of such morphology is also proposed through investigation on the formation process. Photoluminescent spectra suggest that these assemblies doped with Eu3+ can give stronger red emissions than the orange one due to its aragonite structure. Such emission has been explained by the Judd-Ofelt theory. It is expected that these well-defined LaBO3 assemblies could find applications in future luminescent displays and lamps.

A general approach to spindle-assembled lanthanide borate nanocrystals and their photoluminescence upon Eu3+/Tb3+ doping.

Uniform-assembled lanthanide borate nanocrystals have been synthesized via a facile self-assembly process under hydrothermal conditions. All of the prepared lanthanide borate assemblies exhibit a spindle-like profile despite the fact that they belong to different crystal systems and have different formulas for composition. Each assembly is composed of small nanocrystals that are tightly attached along with their lateral surfaces. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy have been used to characterize the structure and morphology of these samples. The mechanism responsible for the growth and assembly of these lanthanide borate assemblies is also demonstrated. After Eu(3+) and/or Tb(3+) ions are doped inside these assemblies, strong and multicolor emissions can be realized. Notably, tunable emission and a warm-white color can be achieved in the Eu(3+)/Tb(3+) codoped samples.

Feasibility investigation of oily wastewater treatment by combination of zinc and PAM in coagulation/flocculation.

Poly-zinc silicate (PZSS) is a new type of coagulant with cationic polymer synthesized by polysilicic acid and zinc sulfate. It has been used in several sorts of wastewaters treatment, but not used in oily wastewater treatment. In this study, we investigated the coagulation/flocculation of oil and suspended solids in heavy oil wastewater (HOW) by PZSS and anion polyacrylamide (A-PAM). The properties of PZSS cooperated with A-PAM were compared with PAC and PFS in dosages, PAMs amount, settling time, pH value and flocs morphology. The results showed that PZSS was more efficient than PAC and PFS. Under the optimum experimental conditions of coagulation/flocculation (dosage: 100mg/L, A-PAM dosage: 1.0mg/L, settling time time: 40min and pH 6.5-9.5), more than 99% of oil was removed and suspended solid value less than 5mg/L by using PZSS cooperated with A-PAM, which could satisfy the demands of the pre-treatment process for HOW to be reused in the steam boiler or recycled into the injecting well.