Biotemplate Method Research Articles

Co 3 O 4 microtubules derived from a biotemplated method for improved lithium storage performance

Abstract A simple and effective biotemplated method is applied to fabricate porous microtubular cobalt oxide by infiltration of cotton fiber with a cobalt nitrate solution, followed by annealing at 500 °C in air. The as-obtained Co 3 O 4 have been characterized by: X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), N 2 adsorption and desorption measurements, and thermal analysis (TG). According to these results, the as-prepared Co 3 O 4 display a perfect tubular morphology and mesoporous features. The electrochemical performance of the as-obtained sample was studied for use as a lithium-ion battery anode material by cyclic voltammetry (CV), and charge-discharge and electrochemical impedance spectroscopy (ESI) measurements. Compared to bulk Co 3 O 4 and previously reported nanostructured Co 3 O 4 electrodes, mesoporous microtubular Co 3 O 4 show an improved lithium storage properties, which can be attributed to their unique morphology, large specific surface area and mesoporous feature.

Hierarchically porous TiO2-MnTiO3/hollow activated carbon fibers heterojunction photocatalysts with synergistic adsorption-photocatalytic performance under visible light

An ideal photocatalysts is expected to not only involve nanoscale subunits with high catalytic activity, but also possess a 3D hierarchically porous microstructure to obtain more activated sites as well as easy recovery. Herein, we demonstrated an efficient route to synthesize self-support hierarchically porous TiO2-MnTiO3/HACFs (hollow activated carbon fibers) heterojunction photocatalysts with tunable band gaps by a facile biotemplated method. The heterojunctions with suitable TiO2/MnTiO3 ratios on HACFs supports had fascinating 3D hollow fiber morphology and exhibited exceptionally synergistic adsorption-photocatalytic activities in visible-light degradation of methylene blue (MB). The photocatalytic degradation rate of MB could reach 99.1% in 60 min under visible light irradiation and cycled experiments showed stably photocatalytic activities. The enhanced photocatalytic performance could be attributed to the high efficiency of electron separation, the high specific surface area and strong adsorption ability toward the MB molecule, and the tunable visible light absorption of TiO2-MnTiO3/HACFs.

Bio-templated fabrication of metal-free boron carbonitride tubes for visible light photocatalysis.

The synthesis of boron carbon nitride (BCN) with special morphologies via a simple pathway is still a major challenge. A novel and facile biotemplating method has been presented to synthesize boron carbon nitride tubes (BCNTs) by using kapok fibers (KFs) as both biotemplates and carbonaceous sources. The BCNT photocatalysts can catalyse hydrogen evolution from water under visible light illumination.

Biomimetic synthesis of cerium oxide nanosquares on RGO and their enhanced photocatalytic activities.

Water splitting based on heterogeneous photocatalytic nanomaterials is an attractive approach for generating hydrogen as a clean chemical fuel from solar energy. However, the high defect-induced recombination rate of photoexcited electron-hole pairs and poor photostability have greatly limited the heterophotocatalysts' practical application. Herein, we used a biotemplate method to give reduced graphene oxide (RGO) a remarkable unique bio-porous morphology with significant anti-aggregation of CeO2 square quantum dots (SQDs) when growing them in situ during a simple hydrothermal process. Biomorphic CeO2 SQDs-RGO has higher electrical conductivity and a narrowed band gap due to there being abundant oxygen vacancies, which results in more effective photo-induced charge generation, transfer and separation. The composite is able to act as an active visible light photocatalyst for highly efficient hydrogen generation applications. Such biomimetic designs could inspire immense research in synthesizing materials with a controlled structure and morphology toward achieving novel graphene-based nanocomposite photocatalysts for solar energy conversion.

Maize straw-templated hierarchical porous ZnO:Ni with enhanced acetone gas sensing properties

Novel maize straw- templated hierarchical porous Ni doped ZnO (STHPS ZnO:Ni) was synthesized by a simple and cost-effective biotemplate method. The structure and morphology of the samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and N2 adsorption–desorption analyses. The results reveal that the as-prepared ZnO:Ni retained the original pore morphology of the maize straw material, and the framework was composed of a large amount of nanoparticles which were nonuniform in size and shape. The gas sensing tests reveal that STHPS ZnO:Ni gas sensors exhibited enhanced gas sensing performance to acetone. The responses of STHPS ZnO:Ni gas sensors to 100ppm acetone operated at 340°C were 68 and the response and recovery times were about 6s and 2s. The detection limit was estimated to be 116 ppb.

Experimental and First-Principles Investigations of Lattice Strain Effect on Electronic and Optical Properties of Biotemplated BiFeO3 Nanoparticles

High purity BiFeO3 nanoparticles were successfully prepared by employing a green and facile biotemplated method which utilized polysaccharides of κ-carrageenan. The particles’ size of BiFeO3 nanoparticles exhibited significant correlations between structural, electronic, and optical properties that have been investigated by both experimental and first-principles methods. First-principles calculations were performed by means of density functional theory (DFT). Structural analysis revealed that the all-prepared BiFeO3 was crystallized in a rhombohedrally distorted structure, along with an average crystallite size of 14.59 nm. The refined lattice parameter and crystal volume obtained by means of the Rietveld refinement method indicated a good agreement with the calculated data; the lattice strain is found in BiFeO3 nanoparticles. From the linear fit using the Kulbeka–Munk method, a small direct and indirect optical energy gap was found to be 2.17 and 1.84 eV, respectively. In addition, first-principles studi...

Fabrication of hollow In2O3–ZnO microtubules by a simple biotemplate method and their gas-sensing properties

Biomorphic In2O3–ZnO hollow microtubules were synthesized by using cotton as template and followed by calcination. This environmental-friendly method using biomaterials as templates can be used to synthesize metal oxide semiconductor materials with specific morphologies. The structural and microscopy characterization were carried out with X-ray diffraction, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy. The SEM images display the porous structure of the as-obtained hollow microtubules, which is beneficial to increase gas sensing properties of materials. Gas sensors based on In2O3-doped ZnO hollow microtubules were investigated and the test results demonstrate the excellent acetone sensing properties of such porous materials. The response of In2O3–ZnO hollow microtubule sensors to 100 ppm acetone at the optimum temperature of 300 °C is 62.5, meanwhile the response and recovery times are 3 and 7 s, respectively. Moreover, even at 0.1 ppm of acetone detectable response can be observed, and the value is 2.82. At the same time the sensors have selectivity to acetone.

Biocatalytic Conversion Efficiency of Steapsin Lipase Immobilized on Hierarchically Porous Biomorphic Aerogel Supports

Hierarchically porous alumino-siloxane aerogels (ALS-PG) with a rare structural architecture were developed through a biotemplating method using pollen grains of Hibiscus rosa-sinensis. The unique structure of the Hibiscus rosa-sinensis pollen makes it an attractive biotemplate, by replicating all levels of macro- and mesoscale morphological features. The micromorphological analysis exposed funnel-shaped macrochannels between the mesoporous aerogel framework that are difficult to design artificially. The N2 sorption analyses confirmed hierarchical trimodal pore size distribution with an average mesopores diameter (ca. 3.9, 8.7, 26.6 nm), high BET/Langmuir surface area (497/664 m2 g–1) and large pore volume (1.6788 cm3 g–1) than the corresponding nontemplated aerogels and xerogels counterpart. Beneficial properties of this sophisticated hierarchical porous structure was examined and confirmed by the immobilization of steapsin lipase. Hierarchically porous ALS-PG showed enhanced loading and immobilization e...

Single-crystalline α-MoO3 microbelts derived from a bio-templating method for superior lithium storage application

Single-crystalline α-MoO3 microbelts with a preferred orientation of (0k0) planes are fabricated by a biological template approach using sugarcane bagasse as template. Benefiting from the excellent crystallinity and preferred orientation, single-crystalline α-MoO3 microbelts show not only an improved electrochemical performance in terms of reversible capacity and rate capability (302 mAhg−1 and 99.4 mAhg−1 at 100 mAg−1 and 2000 mAg−1, respectively), but also an excellent cycling stability (89% of the initial discharge capacity retaining after 200 cycles), thus demonstrating a very high potential for use as a cathode in lithium-ion batteries. This biological template approach could be applied to preparation of other electrode materials for a broad variety of application.

Bio-mediated Sm doped nano cubic zirconia: Photoluminescent, Judd–Ofelt analysis, electrochemical impedance spectroscopy and photocatalytic performance

A series of Sm doped ZrO2 nanomaterials (NMs) were synthesized at relatively low temperature by bio-template method using Leucas aspera (LA) plant extract as a fuel. Rietveld refinement results verified that the compounds were crystallized in cubic structure with space group Fm-3m (225). The PL emission, CIE and CCT analysis confirm that, the present photocatalyst can serve as an excellent candidate for cool LEDs. The registered trend (Ω2 < Ω4) calculated using the Judd–Ofelt theory reveals the ionic character of the SmO bonds as well as a relatively high symmetry environment around the rare earth ion (RE) site in ZrO2. ZrO2:Sm3+ (11 mol%) photocatalyst has a long lifetime (s) and exhibits excellent Sunlight driven photocatalytic activity for the degradation of acid green dye. This could be attributed to surface defects, special electronic structure, decreased band gap, multichannel transitions, long life time and efficient electron−hole separation.

One-pot Biotemplate Synthesis of FeS2 Decorated Sulfur-doped Carbon Fiber as High Capacity Anode for Lithium-ion Batteries

Pyrite FeS2 decorated sulfur-doped carbon (FeS2@S-C) fibers have been successfully synthesized by a facile bio-templating method and applied as the anode material for lithium ion batteries (LIBs). Cotton was used as both the carbon source and the template. SEM and TEM results showed that the FeS2 nanoparticles fabricated using 0.2M FeSO4 were uniformly embedded in or attached on the surface of the carbon fibers. FeS2@S-C synthesized with 0.2M FeSO4 showed the best cycle stability and rate capability, which retained a high reversible specific capacity of 689mAhg−1 after 100 cycles. The specific capacities are about 1200, 900, 700, 550 and 400mAhg−1 after every 10 cycles at 0.1, 0.2, 0.5, 1 and 2Ag−1. The excellent electrochemical performance can be ascribed to the highly conductive sulfur-doped carbon and the homogeneous distribution of FeS2 nanoparticles. It is believed that the S-doped carbon matrix acts as an effective buffer layer helping relieve the volume strain as well as a hinder preventing FeS2 from aggregating during cycling, which ensure the high electrochemical performance. This kind of low-cost anode with high specific capacity and improved cycling stability show potential application for high capacity lithium-ion batteries.

Balancing surface adsorption and diffusion of lithium-polysulfides on nonconductive oxides for lithium-sulfur battery design.

Lithium–sulfur batteries have attracted attention due to their six-fold specific energy compared with conventional lithium-ion batteries. Dissolution of lithium polysulfides, volume expansion of sulfur and uncontrollable deposition of lithium sulfide are three of the main challenges for this technology. State-of-the-art sulfur cathodes based on metal-oxide nanostructures can suppress the shuttle-effect and enable controlled lithium sulfide deposition. However, a clear mechanistic understanding and corresponding selection criteria for the oxides are still lacking. Herein, various nonconductive metal-oxide nanoparticle-decorated carbon flakes are synthesized via a facile biotemplating method. The cathodes based on magnesium oxide, cerium oxide and lanthanum oxide show enhanced cycling performance. Adsorption experiments and theoretical calculations reveal that polysulfide capture by the oxides is via monolayered chemisorption. Moreover, we show that better surface diffusion leads to higher deposition efficiency of sulfide species on electrodes. Hence, oxide selection is proposed to balance optimization between sulfide-adsorption and diffusion on the oxides.

Regenerated cellulose membrane as bio-template for in-situ growth of visible-light driven C-modified mesoporous titania

Visible light driven C-doped mesoporous TiO2 (C-MTiO2) nanorods have been successfully synthesized through green, low cost, and facile approach by sol-gel bio-templating method using regenerated cellulose membrane (RCM) as nanoreactor. In this study, RCM was also responsible to provide in-situ carbon sources for resultant C-MTiO2 nanorods in acidified sol at low temperatures. The composition, crystallinity, surface area, morphological structure, and optical properties of C-MTiO2 nanorods, respectively, had been characterized using FTIR, XRD, N2 adsorption/desorption, TEM, UV–vis-NIR, and XPS spectroscopy. The results suggested that the growth of C-MTiO2 nanorods was promoted by the strong interaction between the hydroxyl groups of RCMs and titanium ion. Optical and XPS analysis confirmed that carbon presence in TiO2 nanorods were responsible for band-gap narrowing, which improved the visible light absorption capability. Photocatalytic activity measurements exhibited the capability of C-MTiO2 nanorods in degradation of methyl orange in aqueous solution, with 96.6% degradation percentage under visible light irradiation.

Porous LiMn2O4 with improved rate capability synthesised by facile biotemplate method

A porous LiMn2O4 has been synthesised by a facile biotemplate method using cornstalk as a biotemplate. The phase composition and micro-morphologies of the products have been investigated by X-ray diffraction and scanning electron microscopy. The results exhibit that the templated LiMn2O4 (LMO-T) is single phase and has better crystallinity than the non-templated LiMn2O4 (LMO). The micro-morphologies of LMO-T are strongly influenced by the template. Templated LiMn2O4 shows a flake-like and porous structure, and the particles of LMO-T with a size of ∼100 nm are uniform and well dispersed. Differently, LMO exhibits a thick layer or bulk and badly agglomerated morphologies. Templated LiMn2O4 exhibits significantly improved electrochemical performance, especially rate capability, compared with LMO, due to its better crystallinity, lower polarisation and lower charge transfer resistance.

Large-scale synthesis of stable mesoporous black TiO2 nanosheets for efficient solar-driven photocatalytic hydrogen evolution via an earth-abundant low-cost biotemplate

Stable mesoporous black anatase TiO2 nanosheets (MBTNs) are synthesized via an earth-abundant low-cost biotemplate method combined with an ethanediamine encircling process, and exhibit excellent solar-driven photocatalytic hydrogen generation.

Biomass derived fabrication of a novel sea cucumber-like LiMn2O4/C composite with a hierarchical porous structure as the cathode for lithium-ion batteries

Biological microstructures display an unparalleled degree of complexity that can be employed as templates to create exquisite architecture of metal oxides in the burgeoning field of materials. In this work, sea cucumber-like LiMn2O4/C composites aggregated by nano-/micro-crystals have been fabricated via a facile biotemplating method using commercial spirulina as sacrificial templates and a simple carbon coated approach. The structure and morphology of the as-obtained products are characterized with X-ray diffraction (XRD) and electron microscopy (SEM and TEM) techniques. The electrochemical test indicates that these unique LiMn2O4/C composites possess the excellent capacity retention and rate property, and the reversible discharge capacity can retain 94% of its initial capacity after 200 cycles at a rate of 10C. The performance improvement may be attributed to the Li+ rapid diffusion in the hierarchical porous structure, and the excellent electron transport of carbon coating as well as their barrier effect for the manganese ions dissolution in cycling.

Biotemplated MnO/C microtubes from spirogyra with improved electrochemical performance for lithium-ion batterys

Biotemplates from microbial origin have been used as a new source of inspiration for designing and fabricating novel functional materials. Herein, we reported a novel MnO/C microtubes prepared by using spirogyra, a green algae growing widely in natural water, as the template. Due to the unique filamentous shape and abundant organism of spirogyra, a porous carbon tube with wrinkle surface has been fabricated. The MnO nanoparticles are set and embedded into the porous carbon matrix, which leads to the tube-like MnO/C composite materials. The as-prepared spirogyra-templated MnO/C microtubes exhibit a reversible electrochemical lithium storage capacity as high as 610mAhg⿿1 at 200mAg⿿1 after 60 cycles, and an excellent rate capability of 350mAhg⿿1 at a high current density of 2Ag⿿1. Considering the vast options of natural materials, this green, facile and economic biotemplating method will provide considerable freedom in structural and functional variability which can be extended to other promising high performance anode materials for the future development of novel energy storage materials.

Facile fabrication of hollow titania microparticles using wet yeast cells as templates

Abstract Hollow titania microparticles were prepared using the bio-templating method with wet yeast cells as templates. Wet yeast cells were used to eliminate fixation or drying of as-cultured cells, and titania shells were formed on the cells via the sol–gel method with tetraisopropyl titanate (TTIP). When the citric acid was used to stabilize TTIP and catalyze TTIP hydrolysis, hollow titania microparticles with well-defined yeast cell morphologies were successfully synthesized. The diameter of the obtained particles was approximately 1.3 μm, and the crystal structure was anatase. The specific surface area and average pore diameter were 41.5 m2/g and 9.6 nm, respectively. Titania nanoparticles generated by homogeneous nucleation were rarely observed over a wide range of water concentrations, indicating that reaction on the biological cell surface, rather than monomer diffusion toward the surface, was rate-limiting. A significant advantage of our method is that the use of dry cultured cells is not required, in contrast to methods using powdered biological cell templates.

Facile preparation and application of magnesium hydroxide assembly spheres

Magnesium hydroxide (Mg(OH)2) assembly spheres were successfully synthesized by use of a facile bio-template method, with Mg(NO3)2 and NaOH solution as reactants. The products were characterized by X-ray diffraction and transmission electron microscopy. The Mg(OH)2 nanomaterial obtained was assembled from nanoflakes and was approximately 2 μm in total size. Eggshell membrane was crucially important in the process of formation of the assembly spheres. The process and mechanism of assembly of the spheres are discussed. When the Mg(OH)2 assembly spheres were used to treat waste water containing heavy metals approximately 100 % of copper ions were removed.

Synthesis of a 3D hierarchical structure of γ-AlO(OH)/Mg–Al-LDH/C and its performance in organic dyes and antibiotics adsorption

We demonstrated an efficient route to synthesize a novel 3D hierarchically porous superstructure composed of edge-to-face stacks of Mg–Al-layered double hydroxide nanosheets, directionally arranged γ-AlO(OH) nanowires and amorphous carbon by a facile biotemplate method.