2 research outputs found
Immobilization of Co–Al Layered Double Hydroxides on Graphene Oxide Nanosheets: Growth Mechanism and Supercapacitor Studies
Layered double hydroxides (LDHs) are generally expressed
as [M<sup>2+</sup><sub>1–<i>x</i></sub>M<sup>3+</sup><sub><i>x</i></sub> (OH)<sub>2</sub>] [A<sup><i>n</i>–</sup><sub><i>x</i>/<i>n</i></sub>·<i>m</i>H<sub>2</sub>O], where M<sup>2+</sup> and M<sup>3+</sup> are divalent and trivalent metal cations respectively, and A is <i>n</i>-valent interlayer guest anion. Co–Al layered double
hydroxides (LDHs) with different sizes have been grown on graphene
oxide (GO) via in situ hydrothermal crystallization. In the synthesis
procedure, the GO is partially reduced in company with the formation
of Co–Al LDHs. The morphology and structure of LDHs/GO hybrids
are characterized by transmission electron microscopy (TEM), scanning
electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron
spectroscopy (XPS) and Raman spectroscopy. The growth mechanism of
LDHs on GO nanosheets is discussed. Moreover, both LDHs and LDHs/graphene
nanosheets (GNS) hybrids are further used as electrochemical supercapacitor
materials and their performance is evaluated by cyclic voltammetry
(CV) and galvanostatic charge/discharge measurements. It is shown
that the specific capacitances of LDHs are significantly enhanced
by the hybridization with GNS
Nitrogen-Doped Graphene Nanoribbons as Efficient Metal-Free Electrocatalysts for Oxygen Reduction
Nitrogen-doped
graphene nanoribbon (N-GNR) nanomaterials with different nitrogen
contents have been facilely prepared via high temperature pyrolysis
of graphene nanoribbons (GNR)/polyaniline (PANI) composites. Here,
the GNRs with excellent surface integration were prepared by longitudinally
unzipping the multiwalled carbon nanotubes. With a high length-to-width
ratio, the GNR sheets are prone to form a conductive network by connecting
end-to-end to facilitate the transfer of electrons. Different amounts
of PANI acting as a N source were deposited on the surface of GNRs
via a layer-by-layer approach, resulting in the formation of N-GNR
nanomaterials with different N contents after being pyrolyzed. Electrochemical
characterizations reveal that the obtained N<sub>8.3</sub>-GNR nanomaterial
has excellent catalytic activity toward an oxygen reduction reaction
(ORR) in an alkaline electrolyte, including large kinetic-limiting
current density and long-term stability as well as a desirable four-electron
pathway for the formation of water. These superior properties make
the N-GNR nanomaterials a promising kind of cathode catalyst for alkaline
fuel cell applications