Bio-templated formation of defect-abundant VS2 as a bifunctional material toward high-performance hydrogen evolution reactions and lithium-sulfur batteries

Transition metal chalcogenides have nowadays garnered burgeoning interest owing to their fascinating electronic and catalytic properties,thus possessing great implications for energy conversion and storage applications.In this regard,their controllable synthesis in a large scale at low cost has readily become a focus of research.Herein we report diatomite-template generic and scalable production of VS2 and other transition metal sulfides targeting emerging energy conversion and storage applications.The conformal growth of VS2over diatomite template would endow them with defect-abundant features.Throughout detailed experimental investigation in combination with theoretical simulation,we reveal that the enriched active sites/sulfur vacancies of thus-derived VS2 architectures would pose positive impacts on the catalytic performance such in electrocatalytic hydrogen evolution reactions.We further show that the favorable electrical conductivity and highly exposed sites of VS2 hold promise for serving as sulfur host in the realm of Li-S batteries.Our work offers new insights into the templated and customized synthesis of defect-rich sulfides in a scalable fashion to benefit multifunctional energy applications.

State of arts on the bio-synthesis of noble metal nanoparticles and their biological application

Nanomaterials are materials in which at least one of the dimensions of the particles is 100 nm and below.There are many types of nanomaterials,but noble metal nanoparticles are of interest due to their uniquely large surface-to-volume ratio,high surface area,optical and electronic properties,high stability,easy synthesis,and tunable surface functionalization.More importantly,noble metal nanoparticles are known to have excellent compatibility with bio-materials,which is why they are widely used in biological applications.The synthesis method of noble metal nanoparticles conventionally involves the reduction of the noble metal salt precursor by toxic reaction agents such as NaBH4,hydrazine,and formaldehyde.This is a major drawback for researchers involved in biological application researches.Hence,the bio-synthesis of noble metal nanoparticles(NPs)by bio-materials via bio-reduction provides an alternative method to synthesize noble metal nanoparticles which are potentially non-toxic and safer for biological application.In this review,the bio-synthesis of noble metal nanoparticle including gold nanoparticle(AuNPs),silver nanoparticle(AgNPs),platinum nanoparticle(PtNPs),and palladium nanoparticle(PdNPs)are first discussed.This is followed by a discussion of these biosynthesized noble metal in biological applications including antimicrobial,wound healing,anticancer drug,and bioimaging.Based on these,it can be concluded that the study on bio-synthesized noble metal nanoparticles will expand further involving bio-reduction by unexplored bio-materials.However,many questions remain on the feasibility of bio-synthesized noble metal nanoparticles to replace existing methods on various biological applications.Nevertheless,the current development of the biological application by bio-synthesized noble metal NPs is still intensively ongoing,and will eventually reach the goal of full commercialization.

Preparation and Characterization of Hydrophobic Nano Silver Film on Butterfly Wings as Bio-template

Hydrophobic nano silver films were fabricated on butterfly wings as bio-template. The micrometric/nano structures and hydrophobicity of the surfaces were investigated with the help of scanning electron microscope（SEM） and video-based contact angle meter. The hydrophobic mechanism of silver film was analyzed with the aid of Cas- sie＇s formula. On the nano silver films of various thicknesses（5, 10, 20, 40, 60, 80, 100 nm）, all the contact an- gles（CAs） of water were bigger than 120°. When the silver film was 5 nm, the CAs of water on it on the wing surfa- ces of Mimathyma nycteis and Speyeria aglaja were 143.2° and 139.2°, respectively. Coated with the sliver film of the same thickness, butterfly wing surface exhibited the CA remarkably bigger than glass slide surface, exhibiting its high hydrophobicity. With the increase of silver film thickness on butterfly wing surface, the hydrophobicity kept de- creasing. The micrometric/nano hierarchical structures on butterfly wing surface result in the transition of metal silver from hydrophilicity to hydrophobicity.

Synthesis of biomimetic cerium oxide by bean sprouts bio-template and its photocatalytic performance

Biomimetic nano CeO2 materials were prepared by using bean sprouts as bio-template through impregnation and thermal decomposition. For characterization of structure, X-ray diffraction spectroscopy （XRD）, field emission scanning electron microscopy （FESEM）, transmission electron microscopy （TEM）, UV-Vis diffuse reflectance spectra （UV-Vis/DRS） nitrogen adsorp- tion-desorption measurements and Labsolar H2 system were adopted. The results demonstrated that the samples prepared at 550 ℃ not only completely removed the original bio-template, but also retained the morphology and microstructure of bean sprouts. Then the biomorphic structure of fluorite structure CeO2 material was obtained. Micro-pores with a diameter of about 2-3 nm were distributed among the particles, which provided more favorable channel for the photocatalytic reaction. Biomimetic CeO2 materials exhibited clear red shift （50 nm） compared with powder CeO2, which could be excited by visible irradiation. Biomimetic CeO2 materials dis- played the superior photocatalytic activity for the hydrogen production by water splitting under the sunlight irradiation, the hydrogen yield could reach 400 ktmol/g catalyst after 6 h.

Facile fabrication of CeO_2 hollow microspheres with yeast as bio-templates

CeO2 hollow microspheres were prepared through a facile method by using yeast cells as bio-templates. The yeast pro- vided a solid flame for the deposition of cerium hydroxide to form the hybrid Ce（OH）3@yeast precursor. The resulting CeO2 hollow microspheres were obtained by calcining the precursor. The products were characterized by field emission scanning electron micros- copy （FE-SEM）, transmission electron microscopy （TEM）, X-ray powder diffraction （XRD）, fourier transform infrared spectroscopy （FTIR）, N2 adsorption/desorption analysis, X-ray photoelectron spectrum （XPS） and H2 temperature programmed reduction （H2-TPR） It was found that the products fully retained the morphology of the yeast cells and the size of the hollow microspheres was about 1.5-2 μm. The catalytic test results showed that the as-obtained hollow CeO2 microspheres possessed a higher catalytic activity in CO oxidation than the commercial CeO2, which attributed to their higher surface area, hollow structure and superior reducibility. This study provided a promising route for the preparation of a variety of other inorganic hollow microspheres.

Bio-template Synthesis of Spirulina/a-Fe2O3 Composite with Improved Surface Wettability

Bio-template method has recently attracted much attention because of its prominent advantages in obtai-ning morphology controlled materials with structural specificity, complexity and their unique functions. The bio-template method combining with electrochemical deposition was employed to synthesize spirulina/hematite composite microstructures using native spirulina as template. A great amount of hematite（a-Fe2O3） nanoparticles can be formed and deposited onto the spirulina, resulting in a robust and pseudo-homogeneous surface. And the spinth- na/a-Fe2O3 composite exhibits an improved surface wettability due to its helical morphology. This facile strategy may open new horizons in the field of replicating specific biological structures for functional materials in other potential applications.

Novel 3D porous graphene decorated with Co_3O_4/CeO_2 for high performance supercapacitor power cell

Tremendous research efforts have been aimed at ever-increasing worldwide energy demand. For this purpose, the hybrid supercapacitor power cell were prepared composing 3D porous graphene decorated with Co_3O_4-CeO_2 nano-particles herein by using flower stem as biotemplate. The resulting samples were characterized by field emission scanning electron microscopy（FESEM）, transmission electron microscopy（TEM）, Raman spectra, X-ray diffraction spectroscopy（XRD）, nitrogen adsorption and desorption, X-ray photoelectron spectrogram（XPS）, and electrochemical test. The 3D graphene acted as an excellent carrier together with Co_3O_4-CeO_2 nano-particles, boosting the specific capacitance of composite（221 F/g）, which exceeded the theoretical value limit. This facile biotemplate method of research provided an eco-friendly and cut-price route to obtain high-quality graphene and Co_3O_4-CeO_2nano-composites owing to the unique porous structure derived from original template（flower stem）. The finding presented a simple strategy for fabrication of novel energy storage devices.