2 research outputs found
Fluorine-Doped SnO<sub>2</sub>@Graphene Porous Composite for High Capacity Lithium-Ion Batteries
For the first time, a composite of
fluorine-doped SnO<sub>2</sub> and reduced graphene oxide (F-SnO<sub>2</sub>@RGO) was synthesized
using a cheap F-containing Sn source, SnÂ(BF<sub>4</sub>)<sub>2</sub>, through a hydrothermal process. X-ray photoelectron spectroscopy
and X-ray diffraction results identified that F was doped in the unit
cells of the SnO<sub>2</sub> nanocrystals, instead of only on the
surfaces of the nanoparticles. F doping of SnO<sub>2</sub> led to
more uniform and higher loading of the F-SnO<sub>2</sub> nanoparticles
on the surfaces of RGO sheets, as well as enhanced electron transportation
and Li ion diffusion in the composite. As a result, the F-SnO<sub>2</sub>@RGO composite exhibited a remarkably high specific capacity
(1277 mA h g<sup>–1</sup> after 100 cycles), a long-term cycling
stability, and excellent high-rate capacity at large charge/discharge
current densities as anode material for lithium ion batteries. The
outstanding performance of the F-SnO<sub>2</sub>@RGO composite electrode
could be ascribed to the combined features of the composite electrode
that dealt with both the electrode dynamics (enhanced electron transportation
and Li ion diffusion due to F doping) and the electrode structure
(uniform decoration of the F-SnO<sub>2</sub> nanoparticles on the
surfaces of RGO sheets and the three-dimensional porous structures
of the F-SnO<sub>2</sub>@RGO composite)
Enhanced Photothermal Bactericidal Activity of the Reduced Graphene Oxide Modified by Cationic Water-Soluble Conjugated Polymer
Surface
modification of graphene is extremely important for applications.
Here, we report a grafting-through method for grafting water-soluble
polythiophenes onto reduced graphene oxide (RGO) sheets. As a result
of tailoring of the side chains of the polythiophenes, the modified
RGO sheets, that is, RGO-<i>g</i>-P3TOPA and RGO-<i>g</i>-P3TOPS, are positively and negatively charged, respectively.
The grafted water-soluble polythiophenes provide the modified RGO
sheets with good dispersibility in water and high photothermal conversion
efficiencies (ca. 88%). Notably, the positively charged RGO-<i>g</i>-P3TOPA exhibits unprecedentedly excellent photothermal
bactericidal activity, because the electrostatic attractions between
RGO-<i>g</i>-P3TOPA and <i>Escherichia coli</i> (<i>E. coli</i>) bind them together, facilitating direct
heat conduction through their interfaces: the minimum concentration
of RGO-<i>g</i>-P3TOPA that kills 100% of <i>E. coli</i> is 2.5 μg mL<sup>–1</sup>, which is only 1/16th of
that required for RGO-<i>g</i>-P3TOPS to exhibit a similar
bactericidal activity. The direct heat conduction mechanism is supported
by zeta-potential measurements and photothermal heating tests, in
which the achieved temperature of the RGO-<i>g</i>-P3TOPA
suspension (2.5 μg mL<sup>–1</sup>, 32 °C) that
kills 100% of <i>E. coli</i> is found to be much lower than
the thermoablation threshold of bacteria. Therefore, this research
demonstrates a novel and superior method that combines photothermal
heating effect and electrostatic attractions to efficiently kill bacteria