Recycling of Secondary Aluminum Dross to Fabricate Porous <i>γ</i>-Al₂O₃Assisted by Corn Straw as Biotemplate

In the aluminum industry, secondary aluminum dross (SAD) is an inevitable solid residue, which usually contains 30 - 70 wt% Al2O3. In this work, Al(OH)3 was extracted from SAD through acid-leaching and alkali purification process. The as-obtained Al(OH)3 precipitation then was calcinated to synthesize porous γ-Al2O3 assisting by an agricultural waste biomass-corn straw as biotemplate. Effects of H2SO4 concentration, reaction temperature and time on the recovery of SAD were investigated. Furthermore, the dependence of calcination temperature on specific surface area, pore volume and content of porous γ-Al2O3 was analyzed. X-ray diffraction (XRD) and X-ray fluorescence (XRF) were used to inspect the phase compositions and their contents, respectively. Scanning electron microscopy (SEM) was employed to analyze the morphologies of the sintered porous γ-Al2O3. It was found that the highest recycle rate of aluminum from SAD was obtained under optimum conditions of 80&#176;C, acid concentration of 1.6 mol/l, and reaction time of 5 h by acid process. The porous γ-Al2O3 with specific surface area, 261.22 m2/g and average pore diameter, 52.64 nm, was obtained under calcination at 850&#176;C through mixing the as-obtained Al(OH)3 precipitation and corn straw.

Electrochemical Impedance Spectroscopic Analysis of ZnS Nanorod Fabricated Using Butterfly Wings as Biotemplate

This article describes the growth of zinc sulfide（ZnS） nanorod on glass/aluminum foil by employing butterfly wings as biotemplate. Upon calcinating（at 400 °C）, the butterfly wings soaked in ZnS nanoparticle suspension, with uniform cage-like nanostructures in nanodimensions, were found on glass/aluminum surface. The transverse and longitudinal dimensions of the nanorods were evaluated from scanning electron microscopy micrographs as 132 and 159 nm,respectively. Purity of the ZnS nanorod found on the specimen was checked by recording XRD（28.877°, 48.038°, and57.174°） and Fourier transform infrared spectrometer spectra（663.7 and 551.68 cm^-1）. Luminescence natures of the nanorods were examined using photoluminescence spectral studies. The characteristic emission peak is shown in the visible region with strong intensity, while the excitation peak is shown at 267 nm. Electrochemical impedance spectroscopic analysis of ZnS nanorod exhibits double-layer capacitance value（Cdl= 6.7 nF）, and the Bode plot explains the stability of ZnS nanorod under the influence of electrical field.

Synthesis of bionic-macro/microporous MgO-modified TiO_2 for enhanced CO_2 photoreduction into hydrocarbon fuels

The stems of water convolvulus were employed as biotemplates for the replication of their optimized 3D hierarchical architecture to synthesize porous MgO-modified TiO2 . The photocatalytic reduction of CO2 with H2O vapor into hydrocarbon fuel was studied with these MgO-TiO2 nanostructures as the photocatalysts with the benefits of improved CO2 adsorption and activation through incorporated MgO. Various factors involving CO2 adsorption capacity, migration of charge carriers to the surface, and the number of activity sites, which depend on the amount of added MgO, determine the photocatalytic conversion efficiency.

Synthesis of biomorphic hierarchical CeO_2 microtube with enhanced catalytic activity

A biomorphic CeO2microtube with multiple-pore structure was fabricated by using the cotton as biotemplate,throughcerium nitrate solution infiltration and thermal decomposition.Field emission scanning electron microscope(FESEM),powder X-raydiffraction(XRD),transmission electron microscope(TEM),N2adsorption?desorption isotherms,temperature-programmedreduction(TPR)and CO oxidation were used to characterize the samples.The results indicated that the synthesized products werecomposed of crystallites with grain size about9nm and exhibited a fibrous morphology similar to the original template andpossessed a specific surface area(BET)of62.3m2/g.Compared with the conventional CeO2particles,the synthesized materialsshowed a superior catalytic activity for CO oxidation.For the synthesized fibrous CeO2,the CO conversion at320°C was above90%and a100%CO conversion was obtained at410°C.

Organic Templates for Inorganic Nanocrystal Growth

Nanocrystals provide a variety of size and shape-dependent properties with applications in a wide range of areas, gaining much attention in the past few years. However, due to the nature of the kinetic nanocrystal growth, the procedures often require strict experimental conditions and the shape and size of nanocrystals are difficult to control. In such context, organic templates, which are artificially modified or synthesized, can direct inorganic nanocrystal nucleation and growth to achieve desired shape, size and ultimately properties. In this review article, two general categories of organic templates used for making inorganic nanomaterials are discussed:biotemplates(e.g., peptide, lipid, DNA, and capsid) and block copolymer templates(e.g., block copolymer micelles, star-like block copolymer unimicelles). The goal of this review is to bridge these gaps and help foster a greater awareness of the range and applicability of different organic templating techniques within the field of nanotechnology.

Preparation of vapreotide-templated silver nanocages and their photothermal therapy efficacy

Vapreotide acetate （Vap） was used as a biotemplate to synthesize silver nanocages through direct co-incubation of a AgNO3 solution, following by reduction using fresh NaBH4. The characterized vapreotide-templated silver nanocages （Vap-AgNCs） presented a wide and red shifted absorption band with a maximum between 480 nm and 800 nm and possessed a uniform structure with a face-centered cubic crystal structure. The biocompatibiliW of Vap-AgNCs was assessed using the MTT method, indicating Vap-AgNCs had better biocompatibility when its concentration was lower than 2,5 × 10-4 mmol. L- 1. The photothermal characteristics of Vap-AgNCs were analyzed with laser irradiation （808 nm, 1,5 W, cm-2） and the results showed that the temperature of the Vap- AgNCs solution reached 45 ℃ starting from 25 ℃ within 5 min. Additionally, Vap-AgNCs with a laser led to HeLa cell death. Therefore, the prepared Vap-AgNCs is expected to be an effective photothermal therapy agent.

Biogenic synthesis and catalysis of porous CeO_2 hollow microspheres

Porous CeO2 hollow microspheres were successfully prepared through a facile process by using the rape pollen as the biotemplate. Scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, the N2 adsorption and desorption, X-ray diffraction （XRD）, UV-vis diffuse reflectance spectra, and hydrogen temperature-programmed reduction （H2-TPR） were used for their characterization. The results showed that the obtained materials exhibited the same morphology as that of the pollen template, with a diameter of ca. 10 μm, and the surface was evenly covered with a special network-like structutre with mesh size of about 0.3 μm, and the Brunauer-Emmett-Teller （BET） surface area was measured to be 156 m2/g. The detailed property investigation inferred that the product exhibited better photocatalytic activity in acid fuchsine decolorization under daylight because of higher surface area, smaller crystallite size and higher oxygen capacity.

Enhanced sulfide chemisorption by conductive AI-doped ZnO decorated carbon nanoflakes for advanced Li-S batteries

Lithium-sulfur batteries have attracted significant attention recently due to their high theoretical capacity, energy density and cost effectiveness. However, sulfur cathodes suffer from issues such as shuttle effects, uncontrollable deposition of lithium sulfides species, and volume expansion of sulfur, which result in rapid capacity fading and low Coulombic efficiency. In recent years, metal-oxide nanostructures have been widely used in Li-S batteries, owing to their effective inhibition of the shuttle effect and controlled deposition of lithium sulfide. However, the nonconductive metal-oxides used in Li-S batteries suffer from extra diffusion process, which slows down the electrochemical reaction kinetics. Herein, we report the synthesis of carbon nanoflakes decorated with conductive aluminium-doped zinc oxide （AZO@C） nanoparticles, through a facile biotem- plating method using kapok fibers as both the template and carbon source. A sulfur cathode based on the AZO@C nanocomposites shows better electrochemical performance than those of cathodes based on ZnO and A1203 with poor conductivity, with a stable capacity of 927 mAh.g-1 at 0.1C （1C = 1,675 mA.g-1） after 100 cycles. A reversible capacity of 544 mAh.g-1 after 300 cycles was obtained even after increasing the current density to 0.5C, with a 0.039% capacity decay per cycle under a sulfur loading of 3.3 mg-cm-2. Moreover, a capacity of 466 mAh.g-1 after 100 cycles at 0.5C could still be obtained when the sulfur loading was increased to 6.96 mg.cm-2. The excellent electrochemical performance of the AZO@C/S composite can be attributed to its high conductivity of the polar AZO host, which suppresses the shuttle effect while simultaneously improving the redox kinetics in the reciprocal transformation of lithium sulfide species.

Three-dimensional biogenic C-doped Bi_2MoO_6/In_2O_3-ZnO Z-scheme heterojunctions derived from a layered precursor

Novel 3D biogenic C-doped Bi_2 MoO_6/In_2O_3-ZnO Z-scheme heterojunctions were synthesized for the first time, using cotton fiber as template. The as-prepared samples showed excellent adsorption and photodegradation performance toward the hazardous antibiotic doxycycline under simulated sunlight irradiation. The morphology, phase composition and in situ carbon doping could be precisely controlled by adjusting processing parameters. The carbon doping in Bi_2 MoO_6/In_2O_3-ZnO was derived from the cotton template, and the carbon content could be varied in the range 0.9–4.4 wt.% via controlling the heat treatment temperature. The sample with Bi_2 MoO_6/In_2O_3-ZnO molar ratio of 1:2 and carbon content of1.1 wt.% exhibited the highest photocatalytic activity toward doxycycline degradation,which was 3.6 and 4.3 times higher than those of pure Bi_2 MoO_6 and Zn In Al-CLDH(calcined layered double hydroxides), respectively. It is believed that the Z-scheme heterojunction with C-doping, the 3D hierarchically micro–meso–macro porous structure, as well as the high adsorption capacity, contributed significantly to the enhanced photocatalytic activity.

Optical Properties of SiO2 and ZnO Nanostructured Replicas of Butterfly Wing Scales

SiO2 and ZnO inverse structure replicas have been synthesized using butterfly wings as templates. The laser diffraction performance of the SiO2 inverse structure replica was investigated and it was found that the zero-order light spot split into a matrix pattern when the distance between the screen and the sample was increased. This unique diffraction phenomenon is closely related to the structure of the SiO2 inverse structure replica. On the other hand, by analyzing the photoluminescence spectrum of the ZnO replica, optical anisotropy in the ultraviolet band was demonstrated for this material.

Controlling the strontium-doping in calcium phosphate microcapsules through yeastregulated biomimetic mineralization

Yeast cells have controllable biosorption on metallic ions during metabolism.However,few studies were dedicated to using yeast-regulated biomimetic mineralization process to control the strontium-doped positions in calcium phosphate microcapsules.In this study,the yeast cells were allowed to pre-adsorb strontium ions metabolically and then served as sacrificing template for the precipitation and calcination of mineral shell.The pre-adsorption enabled the microorganism to enrich of strontium ions into the inner part of the microcapsules,which ensured a slow-release profile of the trace element from the microcapsule.The co-culture with human marrow stromal cells showed that gene expressions of alkaline phosphatase and Collagen-I were promoted.The promotion of osteogenic differentiation was further confirmed in the 3D culture of cell-material complexes.The strategy using living microorganism as‘smart doping apparatus’to control incorporation of trace element into calcium phosphate paved a pathway to new functional materials for hard tissue regeneration.

Denatured proteins as a novel template for the synthesis of well-defined,ultra-stable and water-soluble metal nanostructures for catalytic applications

The templated synthesis of noble metal nanoparticles using biomass,such as proteins and polysaccharides,has generated great interest in recent years.In this work,we report on denatured proteins as a novel template for the preparation of water-soluble metal nanoparticles with excellent stability even after high speed centrifugation or storage at room temperature for one year.Different noble metal nanoparticles including spherical gold and platinum nanoparticles as well as gold nanoflowers are obtained using sodium borohydride or ascorbic acid as the reducing agent.The particle size can be controlled by the concentration of the template.These metal nanoparticles are further used as catalysts for the hydrogenation reaction of p-nitrophenol to p-aminophenol.Especially,spherical gold nanoparticles with an average size of 2 nm show remarkable catalytic performance with a rate constant of 1.026×10^(-2) L s^(-1) mg^(-1).These metal nanoparticles with tunable size and shape have great potential for various applications such as catalysis,energy,sensing,and biomedicine.