0D, 1D, 2D molybdenum disulfide functionalized by 2D polymeric carbon nitride for photocatalytic water splitting.

Photocatalytic activity of molybdenum disulfide structures with different dimensions (0D, 1D and 2D) functionalized with polymeric carbon nitride (PCN) is presented. MoS2nanotubes (1D), nanoflakes (2D) and quantum dots (0D, QDs) were used, respectively, as co-catalysts of PCN in photocatalytic water splitting reaction to evolve hydrogen. Although, 2D-PCN showed the highest light absorption in visible range and the most enhanced photocurrent response after irradiation with light from 460 to 727 nm, QDs-PCN showed the highest photocatalytic efficiency. The detailed analysis revealed that the superior photocatalytic activity of QDs-PCN in comparison with other structures of MoS2arose from (i) the most effective separation of photoexcited electron-hole pairs, (ii) the most enhanced up-converted photoluminescence (UCPL), (iii) the highest reactivity of electrons in conduction band. Moreover, a narrowed size of QDs affected shorter diffusion path of charge carriers to active reaction sites, higher number of the sites and higher interfacial area between molybdenum disulfide and PCN.

Antibacterial performance of nanocrystallined titania confined in mesoporous silica nanotubes.

In this paper, we study synthesis and characteristics of mesoporous silica nanotubes modified by titanium dioxide, as well as their antimicrobial properties and influence on mitochondrial activity of mouse fibroblast L929. Nanocrystalized titania is confined in mesopores of silica nanotubes and its light activated antibacterial response is revealed. The analysis of the antibacterial effect on Escherichia coli. (ATCC 25922) shows strong enhancement during irradiation with the artificial visible and ultraviolet light in respect to the commercial catalyst and control sample free from the nanomaterials. In darkness, the mesoporous silica/titania nanostructures exhibited antibacterial activity dependent on the stirring speed of the suspension containing nanomaterials. Obtained micrograph proved internalization of the sample into the microorganism trough the cell membrane. The analysis of the mitochondrial activity and amount of lactate dehydrogenase released from mouse fibroblast cells L929 in the presence of the sample were determined with LDH and WST1 assays, respectively. The synthesized silica/titania antibacterial agent also exhibits pronounced photoinduced inactivation of the bacterial growth under the artificial visible and UV light irritation in respect to the commercial catalyst. Additionally, mesoporous silica/titania nanotubes were characterized in details by means of high resolution transmission electron microscopy (HR-TEM), XRD and BET Isotherm.

Creation of mesopores in carbon nanotubes with improved capacities for lithium ion batteries.

The porous carbon nanotubes were selectively prepared from the pristine carbon nanotubes. The surface of carbon nanotubes was firstly functionalized with Fe2O3 nanoparticles and subsequent heat treatment induced CNT etching. After removal of Fe2O3 nanoparticles, mesopores were formed in carbon nanotubes and thus porous structure was obtained. The obtained material of porous carbon nanotubes with higher specific surface area and larger pore sizes was tested as anode material of lithium ion batteries and showed improved performance with respect to the pristine carbon nanotubes.

Carbon-nanotube-based stimuli-responsive controlled-release system.

A stimuli-responsive controlled-release delivery system based on carbon nanotubes is demonstrated. Through TEM, FTIR spectroscopic, and thermogravimetric analysis, functional groups have been successfully attached to the open ends of the tubes, thereby enabling functionalized silica spheres to preferentially attach to the ends. This, in essence, plugs the ends of the tube. Controlling release of encapsulated materials within the tubes is illustrated by fluorescein-filled carbon nanotubes. The discharge process can be triggered by exposure to 1,4-dithiothreitol (DTT) or at elevated temperature. Moreover, both triggering systems, DTT and temperature, provide rate of release control through increased DTT concentration or temperature choice, respectively. This delivery system paves the way for the development of a new generation of site-selective, controlled-release, drug-delivery systems, and interactive nanosensor devices.

Synthesis and Characterization of Nitrogen-doped Carbon Nanotubes Derived from g-C3N4.

Here, nitrogen-doped carbon nanotubes (CNT-N) were synthesized using exfoliated graphitic carbon nitride functionalized with nickel oxides (ex-g-C3N4-NixOy). CNT-N were produced at 900 °C in two steps: (1) ex-g-C3N4-NixOy reduction with hydrogen and (2) ethylene assisted chemical vapor deposition (CVD). The detailed characterization of the produced materials was performed via atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The possible mechanism of nanotubes formation is also proposed.

A Comparison of Hydrogen Storage in Pt, Pd and Pt/Pd Alloys Loaded Disordered Mesoporous Hollow Carbon Spheres.

Comprehensive study to evaluate the ability of hydrogen uptake by disordered mesoporous hollow carbon spheres doped witch metal such as Pt, Pd or Pt/Pd was conducted. They were synthesized facilely using sonication and then calcination process under vacuum at the temperature of 550 °C. The effect on hydrogen sorption at neat-ambient conditions (40 °C, up to 45 bar) was thoroughly analyzed. The results clearly revealed that metal functionalization has a significant impact on the hydrogen storage capacity as the mechanism of gas uptake depends on two factors: metal type and certain size of particles. Thus, functionalized spheres adsorb hydrogen by physisorption forming metal hydrides or metal hydrides combined with hydrogen spillover effect. As a result, a sample with narrower distribution of nanoparticles and smaller specific size exhibited enhanced hydrogen uptake.

Oxide-driven carbon nanotube growth in supported catalyst CVD.

Detailed HREM studies on carbon nanotubes (CNTs) synthesized via chemical vapor deposition (CVD) using nanoengineered Fe particles on oxide supports show capped tops and open-ended roots. We demonstrate that the pristine catalyst particle dictates the CNT diameter and number of walls at nucleation. The consecutive inward formation of concentric graphene caps during nucleation constricts and elongates the catalyst particle within the tube core. Continued growth stems from the oxide support.

Porous nanopeapod Pd catalyst with excellent stability and efficiency.

Porous Pd@m-C/SiO2 nanopeapods are prepared by a nanoconfinement method. The Pd nanoparticles show high efficiency and stability in chemical reactions such as reduction of nitrobenzene by H2 and reduction of NO by NH3. The high catalytic activity is attributed to the unique peapod structure, mesoporous wall, and large specific surface area on Pd@m-C/SiO2 rendering the Pd nanoparticles highly active in chemical reactions.

Nanoconfinement induced formation of core/shell structured mesoporous carbon spheres coated with solid carbon shell.

A novel method for the fabrication of core/shell structured mesoporous carbon spheres with solid shell using a template method has been presented. The unique molecular nanostructures are characterized by XRD, TEM, TGA, and nitrogen adsorption/desorption measurement. The formation mechanism of the mesostructured carbon spheres with a carbon shell is proposed according to the experimental results. Nanoconfinement effect, occurring in the core/shell structured template, is believed to play a key role in mediating the formation of these hierarchical carbon mesostructures, with SnO2 as a template and C2H4 as a carbon source of a mesoporous carbon core. This synthesis method is simple, straightforward, and suitable for the preparation of various nanostructures that are unique scaffolds in catalytic and electrochemical applications.

Facile synthesis of hollow silica spheres with nanoholes.

The synthesis of designed nanostructures is an ultimate target of nanomaterial science. Here, silica spheres with nanoholes have been selectively prepared. Coating the necklace-like structured and magnetic nanoparticles along carbon nanotubes, which is an essential step of the simple synthetic procedure of silica hollow spheres, led to the formation of silica hollow spheres with controllable sized nanoholes in their shell walls. The synthesized hollow spheres with nanoholes would be a good support for loading large molecules, e.g. drugs and proteins.

Template method synthesis of mesoporous carbon spheres and its applications as supercapacitors.

Mesoporous carbon spheres (MCS) have been fabricated from structured mesoporous silica sphere using chemical vapor deposition (CVD) with ethylene as a carbon feedstock. The mesoporous carbon spheres have a high specific surface area of 666.8 m2/g and good electrochemical properties. The mechanism of formation mesoporous carbon spheres (carbon spheres) is investigated. The important thing is a surfactant hexadecyl trimethyl ammonium bromide (CTAB), which accelerates the process of carbon deposition. An additional advantage of this surfactant is an increase the yield of product. These mesoporous carbon spheres, which have good electrochemical properties is suitable for supercapacitors.

Synthesis, dispersion, and cytocompatibility of graphene oxide and reduced graphene oxide.

The synthesis, characterization, and toxicity of graphene oxide and reduced graphene oxide are reported. Prior to the cytocompatibility tests the stability of the suspensions in a wide range of concentrations (3.125-100 µg/mL) of three different dispersants is studied. Polyethylene glycol (PEG), polyethylene glycol-polypropylene glycol-polyethylene glycol (Pluronic P123), and sodium deoxycholate (DOC) are investigated as the dispersants. The toxicity depends on the type of dispersant and concentration of the nanomaterials in the suspensions. Detailed analysis suggests that graphene oxide functionalized with PEG in the concentration range between 3125 µg/mL and 25 µg/mL exhibits the best biocompatibility with mice fibroblast cells (line L929).

Magnetic silica nanotubes: synthesis, drug release, and feasibility for magnetic hyperthermia.

A new kind of silica nanotube with incorporated γ-Fe(2)O(3) nanoparticles has been successfully prepared through sol-gel processes. Hematite particles supported on carbon nanotubes served as templates for the fabrication of the magnetic silica nanotubes. The obtained nanostructures consisting of magnetic Fe(2)O(3) nanoparticles protected by a silica shell were fully characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), N(2) sorption and desorption, and magnetization studies. The hollow inner space and the magnetic functionalization render the material promising for applications in biology and medicine. This is underlined by studies in alternating magnetic fields which show a significant heating effect, i.e., the feasibility for applications in hyperthermia therapies. In addition, the material exhibits enhanced drug-loading capacity which is demonstrated by loading with rhodamine B molecules as drugs and corresponding release experiments. The results show that magnetic silica nanotubes can be straightforwardly synthesized and have a great potential as a multifunctional drug carrier system.