Qingli Huang

Facile synthesis of amorphous aluminum vanadate hierarchical microspheres for supercapacitors

Micro-nanostructured mixed metal vanadates have recently garnered enormous attention owing to their remarkable performances in catalysis, energy storage and conversion. In this work, we report the synthesis of amorphous aluminum vanadate hierarchical microspheres via a simple hydrothermal approach with polyvinylpyrrolidone as a surface directing agent. Amorphous aluminum vanadate hierarchical microspheres are firstly described as a kind of electrode material for supercapacitors. The measured specific capacitance of the amorphous aluminum vanadate electrode is 497 F g−1 at 1 A g−1 with good stability and a retention capacity of 89% after 10 000 cycles. In addition, the fabricated asymmetric supercapacitor device delivered better performance with an extended operating voltage window of 1.5 V, excellent cycle stability (10 000 cycles, 85% capacitance retention), high energy density (37.2 W h kg−1 at 1124.4 W kg−1) and high power density (11 250 W kg−1 at 25 W h kg−1). This study essentially offers a new kind of vanadate as an electrochemical active material for the development of supercapacitors.

Facile synthesis of hollow carbon microspheres embedded with molybdenum carbide nanoparticles as an efficient electrocatalyst for hydrogen generation

In an attempt to exploit efficient and stable non-precious-metal electrocatalysts for hydrogen production from water electrolysis in both acid and basic solution, hollow carbon microspheres embedded with molybdenum carbide nanoparticles are prepared via ultrasonic spray pyrolysis. The as-synthesized catalyst exhibits superior activity in hydrogen evolution reaction (HER) with a small overpotential of 203 mV in acidic solution and 346 mV in basic solution to reach a current density of 20 mA cm−2. The enhanced electrochemical activity should be ascribed to the effects of the anchored structure. The catalyst can work stably in both acidic and basic solution with 100% faradaic efficiency. These excellent properties make the catalyst a promising electrocatalyst in the HER.

Mango stone-derived activated carbon with high sulfur loading as a cathode material for lithium–sulfur batteries

A set of mango stone (MS)-derived activated carbons with tunable pore structure parameters have been synthesized via a KOH activation procedure. The maximum specific surface area of 3334 m2 g−1 and pore volume of 2.17 cm3 g−1 are obtained for the material which is pre-carbonized at 500 °C and treated with a KOH/char mass ratio of 4 (a-MSs-500-4). Given the large pore volume of the resultant a-MSs-500-4 activated carbon, a high sulfur loading of up to 71 wt% can be achieved (a-MSs-500-4/71). When applied in a lithium–sulfur battery, the a-MSs-500-4/71 composite cathode exhibits 64% capacity retention over 500 cycles at 800 mA g−1 and 45% capacity retention over 1000 cycles at 1600 mA g−1, indicating excellent long-term cycling performance. Moreover, after 1 wt% LiNO3 is introduced as the electrolyte additive, the average coulombic efficiency of the electrode is as high as approximately 99%.

Synthesis and characterization of an AgI/Ag hybrid nanocomposite with surface-enhanced Raman scattering performance and photocatalytic activity

In this paper, a multifunctional platform for detection and degradation of prohibited colorants based on AgI/Ag hybrid nanocomposites through a facile wet-chemical route was successfully fabricated. The AgI/Ag hybrid nanocomposites were characterized by X-ray diffraction, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), energy-dispersive spectroscopy (EDS) and UV-vis diffuse reflectance spectra (DRS). The surface-enhanced Raman scattering (SERS) performance and photocatalytic activity of the AgI/Ag hybrid nanocomposites were investigated. The results showed that the AgI/Ag hybrid nanocomposites exhibit good SERS performance for malachite green (MG) and excellent photocatalytic activity of rhodamine B (RB). The proposed method has advantages in terms of providing a simple and rapid method for the sensitive analysis of prohibited additive colorants.

Selective synthesis of different ZnO/Ag nanocomposites as surface enhanced Raman scattering substrates and highly efficient photocatalytic catalysts

ZnO/Ag nanocomposites with adjustable surface-enhanced Raman scattering performance and photocatalytic activity were synthesized by a photochemical method. The as-prepared samples were investigated using various spectroscopic and microscopic techniques in detail. Solvents play a key role in controlling the morphologies and properties of these nanocomposites. Detection and degradation of organic dyes is studied. It has been found that suitable experimental parameters are crucial to the detection and degradation of organic dyes molecules. The work is of great importance in practical applications based on the surface-enhanced Raman scattering and photocatalytic performance of noble metal/oxide metal nanocomposites, which could be used for detection and degradation of organic dyes and pollutants.

Synthesis, characterization and application of TiO2/Ag recyclable SERS substrates

In this paper, rutile and anatase TiO2/Ag nanocomposites were prepared by a facile and green photochemical method. The as-prepared samples were investigated by using various spectroscopic and microscopic techniques in detail. Trace detection of rhodamine 6G (R6G) and crystal violet (CV) was studied based on the nanocomposites. Compared to the anatase TiO2/Ag nanocomposite, the rutile TiO2/Ag nanocomposites (Sr3) exhibited the best SERS performance for rhodamine 6G (R6G). Then, the optimized SERS-active substrates (Sr3) were employed to study its recycling properties by degrading R6G and CV in situ. The substrates were able to self-clean. The possible mechanism of the good SERS and photocatalytic performance of the TiO2/Ag nanocomposite (Sr3) was discussed. This work is of importance in theoretical research and practical application based on the SERS effect of nanocomposites.

Self-supported tungsten/tungsten dioxide nanowires array as an efficient electrocatalyst in the hydrogen evolution reaction

In this study, a tungsten/tungsten dioxide (W/WO2) nanowires array (NA) was constructed on a carbon paper (CP) (W/WO2 NA@CP) through the thermal annealing of tungsten trioxide (WO3) NA. W/WO2 NA@CP was proven to be an efficient hydrogen evolution cathode with a strong durability in acidic solutions. W/WO2 NA@CP needs an overpotential of 297 mV to drive a current density of 10 mA cm−2 and 340 mV to drive a current density of 20 mA cm−2. The catalytic activity of W/WO2 NA@CP maintains for at least 50 h in potentiostatic electrolysis. In addition, W/WO2 NA@CP shows nearly a 100% faradaic efficiency during hydrogen generation. The prominent catalytic activity of W/WO2 NA@CP correlates with a large number of active sites for the hydrogen evolution reaction and fast electron transport from the CP to W/WO2 nanowire.

Synthesis of uniform Ag nanosponges and its SERS application

With the aid of amino acid, various Ag nanostructures were successfully synthesized via the reaction between silver nitrate and hydrazine hydrate at room temperature. The as-prepared products were characterized by X-ray diffraction and scanning electron microscopy. It was found that the morphology of the as-prepared Ag products depended on the sorts of amino acid and solvents. The uniform Ag nanosponges could be obtained in glycol with aid of glycine. Using rhodamine 6G (R6G) as probe, the surface-enhanced Raman scattering (SERS) performance was also investigated, which showed that the uniform Ag nanosponges exhibited an intensive and enhanced Raman scattering. Pazufloxacin mesilate (PM) were detected conveniently using these uniform nanosponges as SERS substrates. The present work might afford some guidance for the rationally controllable synthesis of other metal nanomaterials.

Mesoporous Au nanotube-constructed three-dimensional films with excellent SERS performance based on the nanofiber template-displacement reaction strategy

A facile and high-throughput strategy is presented to fabricate three-dimensional hierarchically porous Au films with good flexibility and transferability via displacement reaction of a Ag-coated electrospun nanofiber template. The films are constructed by mesoporous Au nanotubes, homogeneous in the macroscale but rough and porous in the nanoscale. Each nanotube-block is micro/nanostructured with evenly distributed mesopores on the tubewalls. Further experiments have revealed that the Ag sputtering time and displacement reaction conditions are the key influential factors determining the film architecture. Such structured film has exhibited significant surface-enhanced Raman scattering activity with good stability and reproducibility and shown the possibility of molecule-level detection. Additionally, the strategy is general for fabricating other hierarchically porous Au films, such as mesoporous Au hollow sphere arrays.