Transition
metal phosphides (TMPs) have been demonstrated for prospective
applications in electrocatalytic reaction and energy conversion owing
to their specialties of catalytic activity and superhigh theoretical
capacity. Herein, a facile and robust strategy for confining phosphides
in a three-dimensional N,P-codoped carbon skeleton was achieved through
a simple evaporation method. After calcination treatment, metal phosphide
nanoparticles (MP, M = Co, Ni, Fe, and Cu) were successfully encapsulated
in an interconnected N,P-codoped carbon network, which not only endowed
high electrical conductivity and electrochemical stability but also
provided more active sites and ion diffusion channels. As-prepared
CoP@N,P–C exhibited satisfactory hydrogen evolution reaction
activity, displaying lower overpotential of 140 and 197 mV at 10.0
mA cm–2 in 0.5 M H2SO4 and
1.0 M KOH, respectively. Moreover, CoP@N,P–C also delivered
satisfactory lithium-ion storage properties. A higher specific capacity
of 604.9 mAh g–1 was retained after 1000 cycles
at 0.5 A g–1, one of the best reported performances
of CoP-based anode materials. This work highlights a facile pathway
to encapsulate metal phosphides in a conductive carbon skeleton, which
is suitable for scaled-up production of bifunctional composites for
efficient energy storage and conversion.
Constructing
a hierarchical nanostructure has been regarded as
one of the most useful strategies to improve the cycling stability
and rate performance of anode. Herein, hierarchical N-doped carbon
combined with ultrathin WS2 nanosheets (N-C/WS2) was fabricated through a simple chelation coordination method and
sulfuration treatment. Ultrathin WS2 nanosheets with few
layers were embedded in the porous conductive carbon nanosheet structure,
which not only restricted the aggregation of WS2 nanosheets
but also enhanced the ion/electron transfer kinetics during the charge–discharge
procedure. Owing to the robust interaction between WS2 nanosheets
and N-doped carbon, the as-prepared N-C/WS2 exhibited excellent
cycling stability and rate performance in lithium-ion storage. Specifically,
N-C/WS2 anodes delivered an excellent retention capacity
of 600 mAh g–1 after 500 cycles at 1.0 A g–1. This work provides a facile strategy to fabricate a three-dimensional
hierarchical carbon hybrid composed of metal sulfides for energy storage
and conversion fields.
Carbon
fiber composites composed of carbon fiber and pyrolytic
carbon (PyC) matrix have great potential application in the brakes
of aircrafts, where the combination of high mechanical strength and
excellent frictional properties are required. In this work, two-component
silicon-based interlocking enhancements were designed and constructed into carbon fiber composites for
boosting the mechanical and frictional properties. Specially, silicon
carbide nanowires (SiCnws) and silicon nitride nanobelts (Si3N4nbs) could form interlocking architectures, where SiCnws
are rooted firmly on the carbon fiber surface in the radial direction
and Si3N4nbs integrate the PyC matrix with carbon
fibers together via a networked shape. SiCnws–Si3N4nbs not only refine the PyC matrix but also promote
the bonding of the fiber/matrix interface and the cohesion strength
of the PyC matrix, thus enhancing the mechanical and frictional properties.
Benefiting from the SiCnws–Si3N4nbs synergistic
effect and interlocking enhancement mechanism, the interlaminar shear
strength and compressive strength of carbon fiber composites increased
by 88.41% and 73.40%, respectively. In addition, the friction coefficient
and wear rate of carbon fiber composites decreased by 39.50% and 69.88%,
respectively. This work could open up an interlocking enhancement
strategy for efficiently fabricating carbon fiber composites and promoting
mechanical and frictional properties that could be used in the brakes
of aircrafts.
Developing
hierarchical nanostructures composed of transition-metal
dichalcogenides and hollow carbon matrixes is one of the attractive
avenues in energy storage and conversion field on account of their
unique the synergistic effect and stable architecture. Herein, N,
P-codoped hollow carbon nanocomposites combined with WSe2 nanosheets were fabricated via a robust strategy including a metal
chelation coordination method and high-temperature selenization treatment.
Such a typical hollow structure can offer numerous reaction sites
and more diffusion paths to accelerate the transport of Li-ions. In
addition, the carbon substrate is able to enhance electric conductivity
and alleviate the aggregation of the WSe2 nanosheets. As
a result, the as-prepared WSe2 nanosheets/N, P-codoped
carbon nanocomposites deliver the rate capability of 477 mA h g–1 at 5.0 A g–1. This electrode demonstrates
super-durable cyclability after 3000 cycles with the capability of
620 mA h g–1 at 1.0 A g–1. Moreover,
the as-prepared sample displays a high-power density (4987.5 W kg–1), high-energy density (125.1 W h kg–1), and impressive cyclic durability, when assembled with activated
carbon for hybrid Li-ion capacitors. This work proposes an effective
approach to design advanced hierarchical nanostructures in various
energy-related applications.
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