54 research outputs found
Multiplexed Free-Standing Nanowire Transistor Bioprobe for Intracellular Recording: A General Fabrication Strategy
Recent
advance in free-standing nanowire transistor bioprobes opens
up new opportunities of accurately interfacing spatially unobstructed
nanoscale sensors with live cells. However, the existing fabrication
procedures face efficiency and yield limitations when working with
more complex nanoscale building blocks to integrate, for example,
multiplexed recordings or additional functionalities. To date, only
single-kinked silicon nanowires have been successfully used in such
probes. Here we establish a general fabrication strategy to mitigate
such limitations with which synthetically designed complex nanoscale
building blocks can be readily used without causing significant penalty
in yield or fabrication time, and the geometry of the probe can be
freely optimized based on the orientation and structure of the building
blocks. Using this new fabrication framework, we demonstrate the first
multiplexed free-standing bioprobe based on w-shaped silicon kinked
nanowires that are synthetically integrated with two nanoscale field-effect
transistor devices. Simultaneous recording of intracellular action
potentials from both devices have been obtained of a single spontaneously
beating cardiomyocyte
VO<sub>2</sub> Nanowires Assembled into Hollow Microspheres for High-Rate and Long-Life Lithium Batteries
Development
of three-dimensional nanostructures with high surface
area and excellent structural stability is an important approach for
realizing high-rate and long-life battery electrodes. Here, we report
VO<sub>2</sub> hollow microspheres showing empty spherical core with
radially protruding nanowires, synthesized through a facile and controllable
ion-modulating approach. In addition, by controlling the self-assembly
of negatively charged C<sub>12</sub>H<sub>25</sub>SO<sub>4</sub><sup>ā</sup> spherical micelles and positively charged VO<sup>2+</sup> ions, six-armed microspindles and random nanowires are also prepared.
Compared with them, VO<sub>2</sub> hollow microspheres show better
electrochemical performance. At high current density of 2 A/g, VO<sub>2</sub> hollow microspheres exhibit 3 times higher capacity than
that of random nanowires, and 80% of the original capacity is retained
after 1000 cycles. The superior performance of VO<sub>2</sub> hollow
microspheres is because they exhibit high surface area about twice
higher than that of random nanowires and also provide an efficient
self-expansion and self-shrinkage buffering during lithiation/delithiation,
which effectively inhibits the self-aggregation of nanowires. This
research indicates that VO<sub>2</sub> hollow microspheres have great
potential for high-rate and long-life lithium batteries
Design and Synthesis of Diverse Functional Kinked Nanowire Structures for Nanoelectronic Bioprobes
Functional kinked nanowires (KNWs) represent a new class
of nanowire
building blocks, in which functional devices, for example, nanoscale
field-effect transistors (nanoFETs), are encoded in geometrically
controlled nanowire superstructures during synthesis. The bottom-up
control of both structure and function of KNWs enables construction
of spatially isolated point-like nanoelectronic probes that are especially
useful for monitoring biological systems where finely tuned feature
size and structure are highly desired. Here we present three new types
of functional KNWs including (1) the zero-degree KNW structures with
two parallel heavily doped arms of U-shaped structures with a nanoFET
at the tip of the āUā, (2) series multiplexed functional
KNW integrating multi-nanoFETs along the arm and at the tips of V-shaped
structures, and (3) parallel multiplexed KNWs integrating nanoFETs
at the two tips of W-shaped structures. First, U-shaped KNWs were
synthesized with separations as small as 650 nm between the parallel
arms and used to fabricate three-dimensional nanoFET probes at least
3 times smaller than previous V-shaped designs. In addition, multiple
nanoFETs were encoded during synthesis in one of the arms/tip of V-shaped
and distinct arms/tips of W-shaped KNWs. These new multiplexed KNW
structures were structurally verified by optical and electron microscopy
of dopant-selective etched samples and electrically characterized
using scanning gate microscopy and transport measurements. The facile
design and bottom-up synthesis of these diverse functional KNWs provides
a growing toolbox of building blocks for fabricating highly compact
and multiplexed three-dimensional nanoprobes for applications in life
sciences, including intracellular and deep tissue/cell recordings
Ultralong Sb<sub>2</sub>Se<sub>3</sub> Nanowire-Based Free-Standing Membrane Anode for Lithium/Sodium Ion Batteries
Metal chalcogenides
have emerged as promising anode materials for lithium ion batteries
(LIBs) and sodium ion batteries (SIBs). Herein, a free-standing membrane
based on ultralong Sb<sub>2</sub>Se<sub>3</sub> nanowires has been
successfully fabricated via a facile hydrothermal synthesis combined
with a subsequent vacuum filtration treatment. The as-achieved free-standing
membrane constructed by pure Sb<sub>2</sub>Se<sub>3</sub> nanowires
exhibits good flexibility and integrity. Meanwhile, we investigate
the lithium and sodium storage behavior of the Sb<sub>2</sub>Se<sub>3</sub> nanowire-based free-standing membrane. When applied as the
anode for LIBs, it delivers a reversible capacity of 614 mA h g<sup>ā1</sup> at 100 mA g<sup>ā1</sup>, maintaining 584
mA h g<sup>ā1</sup> after 50 cycles. When applied as the anode
for SIBs, it delivers a reversible capacity of 360 mA h g<sup>ā1</sup> at 100 mA g<sup>ā1</sup>, retaining 289 mA h g<sup>ā1</sup> after 50 cycles. Such difference in electrochemical performance
can be attributed to the more complex sodiation process relative to
the corresponding lithiation process. This work may provide insight
on developing Sb<sub>2</sub>Se<sub>3</sub>-based anode materials for
high-performance LIBs or SIBs
Lipoic Acid-Assisted In Situ Integration of Ultrathin Solid-State Electrolytes
Ultrathin
solid-state electrolytes (SSEs) have contributed to high-energy-density
lithium-ion batteries (LIBs). However, when reducing thickness of
SSEs, mechanical properties will inevitably deteriorate, even increasing
the safety hazards. In this work, we developed an in-situ integration
strategy to form an ultrathin SSE by combining a lipoic acid-assisted
semi-interpenetrating polymer network and an ultrathin porous membrane.
With this strategy, the thickness of the obtained SSE (named LA-SSE)
is only 10 Ī¼m, and the LA-SSE possesses extraordinary mechanical
performances to suppress the growth of lithium dendrites. Meanwhile,
the flexible LA-SSE presents anionic conductivity of 0.036 mS cmā1 and promotes interfacial compatibility between the
lithium anode and the electrolyte. By employing LA-SSE as the electrolyte,
the assembled Liā„LA-SSEā„Li symmetric cell operated with
long-term cycling (more than 3000 h), and the LiFePO4ā„LA-SSEā„Li
full battery worked steadily over 200 cycles at 0.5 C with a capacity
retention of 84% at room temperature. This work provides a promising
strategy for designing ultrathin SSEs, with satisfactory mechanical
properties, excellent interfacial compatibility, and safety, for LIBs
Synergistic Effect of Hierarchical Nanostructured MoO<sub>2</sub>/Co(OH)<sub>2</sub> with Largely Enhanced Pseudocapacitor Cyclability
Pseudocapacitors have demonstrated
an ability to deliver high energy
and power densities. The main limitation is their poor cyclability
and for this reason the architectural design of electrode materials
has attracted considerable attention. Here we report the synthesis
of hierarchical nanostructured material by growing CoĀ(OH)<sub>2</sub> nanoflakes onto MoO<sub>2</sub> thin film. The electrode material
exhibits a high capacitance of 800 F g<sup>ā1</sup> at 20 A
g<sup>ā1</sup> with only 3% capacitance loss after 5000 cycles
and high rate capability with increasing current density from 2 to
40 A g<sup>ā1</sup>, which are better than those of individual
component. The enhanced pseudocapacitor performances benefit from
the synergistic effect of the hierarchical nanostructure: (1) faster
ion diffusion and electron transport at electrode/electrolyte interface,
and (2) mitigation of the electrode destruction caused by ion insertion/deinsertion
during charge-storage process. This facile design and rational synthesis
offers an effective strategy to enhance the electrochemical performance
of pseudocapacitors and shows promising potential for large-scale
application in energy storage
Enhancement of Photovoltaic Performance by Utilizing Readily Accessible Hole Transporting Layer of Vanadium(V) Oxide Hydrate in a PolymerāFullerene Blend Solar Cell
Herein,
a successful application of V<sub>2</sub>O<sub>5</sub>Ā·<i>n</i>H<sub>2</sub>O film as hole transporting layer (HTL) instead
of PEDOT:PSS in polymer solar cells is demonstrated. The V<sub>2</sub>O<sub>5</sub>Ā·<i>n</i>H<sub>2</sub>O layer was spin-coated
from V<sub>2</sub>O<sub>5</sub>Ā·<i>n</i>H<sub>2</sub>O sol made from melting-quenching solāgel method by directly
using vanadium oxide powder, which is readily accessible and cost-effective.
V<sub>2</sub>O<sub>5</sub>Ā·<i>n</i>H<sub>2</sub>O (<i>n</i> ā 1) HTL is found to have comparable work function
and smooth surface to that of PEDOT:PSS. For the solar cell containing
V<sub>2</sub>O<sub>5</sub>Ā·<i>n</i>H<sub>2</sub>O HTL
and the active layer of the blend of a novel polymer donor (PBDSe-DT2PyT)
and the acceptor of PC<sub>71</sub>BM, the PCE was significantly improved
to 5.87% with a 30% increase over 4.55% attained with PEDOT:PSS HTL.
Incorporation of V<sub>2</sub>O<sub>5</sub>Ā·<i>n</i>H<sub>2</sub>O as HTL in the polymer solar cell was found to enhance
the crystallinity of the active layer, electron-blocking at the anode
and the light-harvest in the wavelength range of 400ā550 nm
in the cell. V<sub>2</sub>O<sub>5</sub>Ā·<i>n</i>H<sub>2</sub>O HTL improves the charge generation and collection and suppress
the charge recombination within the PBDSe-DT2PyT:PC<sub>71</sub>BM
solar cell, leading to a simultaneous enhancement in <i>V</i><sub>oc</sub>, <i>J</i><sub>sc</sub>, and FF. The V<sub>2</sub>O<sub>5</sub>Ā·<i>n</i>H<sub>2</sub>O HTL proposed
in this work is envisioned to be of great potential to fabricate highly
efficient PSCs with low-cost and massive production
Electrostatic Assembly of Sandwich-like Ag-C@ZnO-C@AgāC Hybrid Hollow Microspheres with Excellent High-Rate Lithium Storage Properties
Herein,
we introduce a facile electrostatic attraction approach to produce
zincāsilver
citrate hollow microspheres, followed by thermal heating treatment
in argon to ingeniously synthesize sandwich-like Ag-C@ZnO-C@Ag-C hybrid
hollow microspheres. The 3D carbon conductive framework in the hybrids
derives from the <i>in situ</i> carbonation of carboxylate
acid groups in zincāsilver citrate hollow microspheres during
heating treatment, and the continuous and homogeneous Ag nanoparticles
on the outer and inner surfaces of hybrid hollow microspheres endow
the shells with the sandwiched configuration (Ag-C@ZnO-C@Ag-C). When
applied as the anode materials for lithium ion batteries, the fabricated
hybrid hollow microspheres with sandwich-like shells reveal a very
large reversible capacity of 1670 mAh g<sup>ā1</sup> after
200 cycles at a current density of 0.2 A g<sup>ā1</sup>. Even
at the very large current densities of 1.6 and 10.0 A g<sup>ā1</sup>, the high specific capacities of about 1063 and 526 mAh g<sup>ā1</sup> can be retained, respectively. The greatly enhanced electrochemical
properties of Ag-C@ZnO-C@Ag-C hybrid microspheres are attributed to
their special structural features such as the hollow structures, the
sandwich-like shells, and the nanometer-sized building blocks
NiSe<sub>2</sub> Nanooctahedra as an Anode Material for High-Rate and Long-Life Sodium-Ion Battery
In
this article, we report NiSe<sub>2</sub> nanooctahedra as a promising
anode material for sodium-ion batteries (SIBs). They exhibit outstanding
long-term cyclic stability (313 mAh/g after 4000 cycles at 5 A/g)
and excellent high-rate capability (175 mAh/g at 20 A/g). Besides,
the initial Coulombic efficiency of NiSe<sub>2</sub> is also very
impressive (over 90%). Such remarkable performances are attributed
to good conductivity, structural stability, and the pseudocapacitive
behavior of the NiSe<sub>2</sub>. Furthermore, the sodium ion storage
mechanism of NiSe<sub>2</sub> is first investigated by <i>in
situ</i> XRD and <i>ex situ</i> XRD. These highlights
give NiSe<sub>2</sub> a competitive strength for rechargeable SIBs
Porous and Low-Crystalline Manganese Silicate Hollow Spheres Wired by Graphene Oxide for High-Performance Lithium and Sodium Storage
Herein,
a graphene oxide (GO)-wired manganese silicate (MS) hollow sphere
(MS/GO) composite is successfully synthesized. Such an architecture
possesses multiple advantages in lithium and sodium storage. The hollow
MS structure provides a sufficient free space for volume variation
accommodation; the porous and low-crystalline features facilitate
the diffusion of lithium ions; meanwhile, the flexible GO sheets enhance
the electronic conductivity of the composite to a certain degree.
When applied as the anode material for lithium-ion batteries (LIBs),
the as-obtained MS/GO composite exhibits a high reversible capacity,
ultrastable cyclability, and good rate performance. Particularly,
the MS/GO composite delivers a high capacity of 699 mA h g<sup>ā1</sup> even after 1000 cycles at 1 A g<sup>ā1</sup>. The sodium-storage
performance of MS/GO has been studied for the first time, and it delivers
a stable capacity of 268 mA h g<sup>ā1</sup> after 300 cycles
at 0.2 A g<sup>ā1</sup>. This study suggests that the rational
design of metal silicates would render them promising anode materials
for LIBs and SIBs
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