5 research outputs found
Ordered Mesoporous Platinum@Graphitic Carbon Embedded Nanophase as a Highly Active, Stable, and Methanol-Tolerant Oxygen Reduction Electrocatalyst
Highly ordered mesoporous platinum@graphitic carbon (Pt@GC)
composites
with well-graphitized carbon frameworks and uniformly dispersed Pt
nanoparticles embedded within the carbon pore walls have been rationally
designed and synthesized. In this facile method, ordered mesoporous
silica impregnated with a variable amount of Pt precursor is adopted
as the hard template, followed by carbon deposition through a chemical
vapor deposition (CVD) process with methane as a carbon precursor.
During the CVD process, in situ reduction of Pt precursor, deposition
of carbon, and graphitization can be integrated into a single step.
The mesostructure, porosity and Pt content in the final mesoporous
Pt@GC composites can be conveniently adjusted over a wide range by
controlling the initial loading amount of Pt precursor and the CVD
temperature and duration. The integration of high surface area, regular
mesopores, graphitic nature of the carbon walls as well as highly
dispersed and spatially embedded Pt nanoparticles in the mesoporous
Pt@GC composites make them excellent as highly active, extremely stable,
and methanol-tolerant electrocatalysts toward the oxygen reduction
reaction (ORR). A systematic study by comparing the ORR performance
among several carbon supported Pt electrocatalysts suggests the overwhelmingly
better performance of the mesoporous Pt@GC composites. The structural,
textural, and framework properties of the mesoporous Pt@GC composites
are extensively studied and strongly related to their excellent ORR
performance. These materials are highly promising for fuel cell applications
and the synthesis method is quite applicable for constructing mesoporous
graphitized carbon materials with various embedded nanophases
Additional file 1: of Effects of ultrasound-guided stellate ganglion block on cervical vascular blood flow: study protocol for a randomized controlled trial
SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials). Completed SPIRIT 2013 checklist of recommended items to address in a clinical trial protocol and related documents. (DOC 123 kb
Two-Dimensional Mesoporous Carbon Nanosheets and Their Derived Graphene Nanosheets: Synthesis and Efficient Lithium Ion Storage
We report a new solution deposition method to synthesize
an unprecedented
type of two-dimensional ordered mesoporous carbon nanosheets via a
controlled low-concentration monomicelle close-packing assembly approach.
These obtained carbon nanosheets possess only one layer of ordered
mesopores on the surface of a substrate, typically the inner walls
of anodic aluminum oxide pore channels, and can be further converted
into mesoporous graphene nanosheets by carbonization. The atomically
flat graphene layers with mesopores provide high surface area for
lithium ion adsorption and intercalation, while the ordered mesopores
perpendicular to the graphene layer enable efficient ion transport
as well as volume expansion flexibility, thus representing a unique
orthogonal architecture for excellent lithium ion storage capacity
and cycling performance. Lithium ion battery anodes made of the mesoporous
graphene nanosheets have exhibited an excellent reversible capacity
of 1040 mAh/g at 100 mA/g, and they can retain at 833 mAh/g even after
numerous cycles at varied current densities. Even at a large current
density of 5 A/g, the reversible capacity is retained around 255 mAh/g,
larger than for most other porous carbon-based anodes previously reported,
suggesting a remarkably promising candidate for energy storage
Enhanced Electrochemical and Thermal Transport Properties of Graphene/MoS<sub>2</sub> Heterostructures for Energy Storage: Insights from Multiscale Modeling
Graphene
has been combined with molybdenum disulfide (MoS<sub>2</sub>) to ameliorate
the poor cycling stability and rate performance of MoS<sub>2</sub> in lithium ion batteries, yet the underlying mechanisms remain less
explored. Here, we develop multiscale modeling to investigate the
enhanced electrochemical and thermal transport properties of graphene/MoS<sub>2</sub> heterostructures (GM-Hs) with a complex morphology. The calculated
electronic structures demonstrate the greatly improved electrical
conductivity of GM-Hs compared to MoS<sub>2</sub>. Increasing the
graphene layers in GM-Hs not only improves the electrical conductivity
but also stabilizes the intercalated Li atoms in GM-Hs. It is also
found that GM-Hs with three graphene layers could achieve and maintain
a high thermal conductivity of 85.5 W/(m·K) at a large temperature
range (100–500 K), nearly 6 times that of pure MoS<sub>2</sub> [∼15 W/(m·K)], which may accelerate the heat conduction
from electrodes to the ambient. Our quantitative findings may shed
light on the enhanced battery performances of various graphene/transition-metal
chalcogenide composites in energy storage devices
Interface Tension-Induced Synthesis of Monodispersed Mesoporous Carbon Hemispheres
Here we report a novel interface
tension-induced shrinkage approach
to realize the synthesis of monodispersed asymmetrical mesoporous
carbon nanohemispheres. We demonstrate that the products exhibit very
uniform hemispherical morphology (130 × 60 nm) and are full of
ordered mesopores, endowing them high surface areas and uniform pore
sizes. These monodispersed mesoporous carbon hemispheres display excellent
dispersibility in water for a long period without any aggregation.
Moreover, a brand new feature of the mesoporous carbon materials has
been observed for the first time: these monodispersed mesoporous carbon
hemispheres show excellent thermal generation property under a NIR
irradiation