Effective Electrochemical Activation of Oleate-Residue-Fouled Pt Nanoparticle Catalysts for Methanol and Formic Acid Oxidation.

Platinum plays a crucial role in the field of basic electrochemistry, regeneration energy, and so on. Pt nanomaterials with well-controlled size and shape could be easily obtained from metal-oleate complexes. However, these nanoparticles (NPs) were electrochemically inactive because of the attached organic residue. This work has been reported as a robust method to remove the residues from the surface of Pt nanoparticle catalysts by the electrochemical treatment in alkaline media. After the electrochemical activation, the Pt nanoparticle catalysts show good catalytic behavior toward the electrochemical oxidation of methanol and formic acid.

Scalable Synthesis of Honeycomb-like Ordered Mesoporous Carbon Nanosheets and Their Application in Lithium-Sulfur Batteries.

There is a growing need to improve the electrical conductivity of the cathode and to suppress the rapid capacity decay during cycling in lithium-sulfur (Li-S) batteries. This can be achieved by developing facile methods for the synthesis of novel nanostructured carbon materials that can function as effective cathode hosts. In this Article, we report the scalable synthesis of ordered mesoporous carbon nanosheets (OMCNS) via the etching of self-assembled iron oxide/carbon hybrid nanosheets (IO-C NS), which serve as an advanced sulfur host for Li-S batteries. The obtained two-dimensional (2D) nanosheets have close-packed uniform cubic mesopores of ∼20 nm side length, and the gap between the pores is ∼4 nm, which resembles the honeycomb structure consisting of an ordered array of hexagonal pores. We loaded OMCNS with sulfur by a simple melting infusion process and evaluated the performance of the resulting OMCNS-sulfur composites as the cathode material. As a result, the sulfur-loaded OMCNS hybrid (OMCNS-S) electrode infiltrated with 70 wt % sulfur delivers a high and stable reversible capacity of 505.7 mA h g-1 after 500 cycles at 0.5 C-rate with excellent capacity retention (a decay of 0.081% per cycle) and excellent rate capability (580.6 mA h g-1 at a high current density of 2 C). The improved electrochemical properties could be attributed to the fact that the uniform cubic mesopores offer sufficient space for the volume expansion of sulfur inside them and therefore trap the polysulfides during the charging-discharging process. Therefore, these unique structured carbon nanosheets can be promising candidates for other energy-storage applications.

Scalable Synthesis of Few-Layer MoS2 Incorporated into Hierarchical Porous Carbon Nanosheets for High-Performance Li- and Na-Ion Battery Anodes.

It is still a challenging task to develop a facile and scalable process to synthesize porous hybrid materials with high electrochemical performance. Herein, a scalable strategy is developed for the synthesis of few-layer MoS2 incorporated into hierarchical porous carbon (MHPC) nanosheet composites as anode materials for both Li- (LIB) and Na-ion battery (SIB). An inexpensive oleylamine (OA) is introduced to not only serve as a hinder the stacking of MoS2 nanosheets but also to provide a conductive carbon, allowing large scale production. In addition, a SiO2 template is adopted to direct the growth of both carbon and MoS2 nanosheets, resulting in the formation of hierarchical porous structures with interconnected networks. Due to these unique features, the as-obtained MHPC shows substantial reversible capacity and very long cycling performance when used as an anode material for LIBs and SIBs, even at high current density. Indeed, this material delivers reversible capacities of 732 and 280 mA h g(-1) after 300 cycles at 1 A g(-1) in LIBs and SIBs, respectively. The results suggest that these MHPC composites also have tremendous potential for applications in other fields.

Facile synthesis of one-dimensional iron-oxide/carbon hybrid nanostructures as electrocatalysts for oxygen reduction reaction in alkaline media.

One-dimensional iron-oxide/carbon hybrid nano tubular structures were synthesized via anodic aluminium oxide (AAO) template method. Highly unform iron oxide nanoparticles and carbon structures were formed simultaneously on the wall surface of the AAO template from an iron-oleate precursor by solventless thermal decomposition method. The 1D iron-oxide/carbon nanostructures were obtained after removing the AAO template. The typical size of the iron oxide nanoparticles was - 6 nm, and the nanoparticles had a crystalline structure of maghemite (γ-Fe2O3), which was determined from the HRTEM and X-ray diffraction (XRD). This nanocrystalline spinel structure could provide more active sites for oxygen reduction reaction (ORR) catalysis due to the higher specific surface area and numerous defects. As an ORR catalyst, the hybrid nanotubes showed higher limiting mass activity (8.8 A/g) and a more positive onset potential (-0.241 V, vs. Hg/HgCl) than iron oxide nanoparticles in alkaline media. This electrocatalytic activity of the nanocomposites is mainly attributed to the synergetic effects of the iron oxide nanoparticles and carbon matrix in the one-dimensional nanostructure.

A chemically activated graphene-encapsulated LiFePO4 composite for high-performance lithium ion batteries.

A composite of modified graphene and LiFePO4 has been developed to improve the speed of charging-discharging and the cycling stability of lithium ion batteries using LiFePO4 as a cathode material. Chemically activated graphene (CA-graphene) has been successfully synthesized via activation by KOH. The as-prepared CA-graphene was mixed with LiFePO4 to prepare the composite. Microscopic observation and nitrogen sorption analysis have revealed the surface morphologies of CA-graphene and the CA-graphene/LiFePO4 composite. Electrochemical properties have also been investigated after assembling coin cells with the CA-graphene/LiFePO4 composite as a cathode active material. Interestingly, the CA-graphene/LiFePO4 composite has exhibited better electrochemical properties than the conventional graphene/LiFePO4 composite as well as bare LiFePO4, including exceptional speed of charging-discharging and excellent cycle stability. That is because the CA-graphene in the composite provides abundant porous channels for the diffusion of lithium ions. Moreover, it acts as a conducting network for easy charge transfer and as a divider, preventing the aggregation of LiFePO4 particles. Owing to these properties of CA-graphene, LiFePO4 could demonstrate enhanced and stably long-lasting electrochemical performance.

Highly monodisperse rattle-structured nanomaterials with gold nanorod core-mesoporous silica shell as drug delivery vehicles and nanoreactors.

Rattle-structured nanomaterials composed of a gold nanorod in a mesoporous silica nanocapsule (AuNR@mSiO(2)) were prepared by a novel solution-based consecutive process. The drug-loading properties of the nanomaterial and regrowth control of the core nanoparticles were also studied.

Direct synthesis of self-assembled ferrite/carbon hybrid nanosheets for high performance lithium-ion battery anodes.

Extensive applications of rechargeable lithium-ion batteries (LIBs) to various portable electronic devices and hybrid electric vehicles result in the increasing demand for the development of electrode materials with improved electrochemical performance including high energy, power density, and excellent cyclability, while maintaining low production cost. Here, we present a direct synthesis of ferrite/carbon hybrid nanosheets for high performance lithium-ion battery anodes. Uniform-sized ferrite nanocrystals and carbon materials were synthesized simultaneously through a single heating procedure using metal-oleate complex as the precursors for both ferrite and carbon. 2-D nanostructures were obtained by using sodium sulfate salt powder as a sacrificial template. The 2-D ferrite/carbon nanocomposites exhibited excellent cycling stability and rate performance derived from 2-D nanostructural characteristics. The synthetic procedure is simple, inexpensive, and scalable for mass production, and the highly ordered 2-D structure of these nanocomposites has great potential for many future applications.

Prevention of tissue injury by ribbon antisense to TGF-beta1 in the kidney.

Transforming growth factor-beta1 (TGF-beta1) is an important mediator of glomerulosclerosis and tubulointerstitial fibrosis in renal diseases. We designed ribbon-type antisense oligos of TGF-beta1, TGF-beta1 RiAS, and combined them with a short peptide of the nuclear localization signal to form a transfection complex of DNA/peptide/liposomes (DPL) for enhanced cellular uptake. When H4IIE cells were transfected with TGF-beta1 RiAS, the level of TGF-beta1 mRNA was reduced by >70%. We then examined the ratio of the kidney weight per body weight in rats. Whereas the weight ratio was 0.47% for the normal kidney, the ratio was 0.99% on day 5 after unilateral ureteric obstruction (UUO). The ratios were 0.95% with PBS injection, 1.07% with scrambled RiAS, and 0.68% with TGF-beta1 RiAS. When examined for TGF-beta1 expression in the tissue, the level of TGF-beta1 mRNA was also significantly reduced following treatment with TGF-beta1 RiAS. Further, physical changes such as diminished dilation, atrophy, as well as apoptosis caused by UUO were also found to be markedly reduced by TGF-beta1 RiAS. The results show that ribbon antisense to TGF-beta1 when combined with efficient uptake can effectively block TGF-beta1 expression and preserve tissue integrity in kidneys with UUO.