7 research outputs found
Superelastic Graphene Aerogels Constructed by Structural Modulation for Piezoresistive Sensing
The microstructure is a critical factor in determining
the macroscopic
properties of aerogel materials and has a significant impact on their
performance in various application scenarios. Here, drawing inspiration
from the microstructure regulation of the bubble template, polyvinylpyrrolidone
(PVP) was used to microscopically regulate graphene oxide nanosheets
in the fabrication of the graphene aerogel (GA). Simultaneously, sodium
dodecyl sulfate (SDS) foaming was employed as the bubble template
to aid in the construction of PVP/SDS-GA (PSGA) with a hierarchical
porous structure. Such an innovative structural blueprint inherently
promotes a more even distribution of stress, thereby enhancing the
compressive strength of the aerogel. The advanced architecture of
PSGA enables rapid desiccation by using ambient pressure and elevated
thermal methods, simplifying the fabrication process. PSGA possesses
several remarkable characteristics: an ultralow density of 2.84 mg/cm3, a high electrical conductivity of 10 S/m, a superelasticity
with an extreme strain of 99%, an outstanding fatigue resistance with
the ability to withstand 10,000 cycles at 70% strain, and a high compressive
strength of 0.66 MPa. In light of these characteristics, the piezoresistive
sensor conceptualized using PSGA as a foundational substrate exhibited
superior signal discernment capabilities
Biodegradable and biocompatible alginate/gelatin/MXene composite membrane with efficient osteogenic activity and its application in guided bone regeneration
Guided bone regeneration (GBR) utilizes a barrier membrane to maintain the osteogenic space and promote osseointegration of the implants. Developing a novel biomaterial to meet the mechanical and biological performance requirements of GBR membrane (GBRM) remains a huge challenge. Here, the sodium alginate (SA, S)/gelatin (G)/MXene (M) composite membrane (SGM) was prepared by combining sol-gel and freeze-drying processes. The incorporation of MXene improved the mechanical properties and hydrophilicity of the SA/G (SG) membrane, and also enhanced its cell proliferation and osteogenic differentiation. More importantly, when the concentration of MXene is 0.25%W/V, the SGM composite membrane exhibited the best tensile strength (40 MPa), high swelling rate (1012%), and appropriate degradation rate (40%). Meanwhile, the biological improvements were more significant. Therefore, the appropriate amount addition of MXene has a positive and obvious effect on the improvements of the mechanical properties, biocompatibility, and osteogenic induction of the SG composite membranes. This work provides a more extendable development idea for the application of SGM composite membrane as GBRM.</p
Fluorine Doping Strengthens the Lithium-Storage Properties of the Mn-Based Metal–Organic Framework
The
electrochemical properties of the metal–organic framework (MOF)-based
composite as electrode material can be significantly improved by means
of partial destruction of the full coordination of linkers to metal
ions and replacing with other small ions, which make metal centers
become more accostable and consequently more effective for the lithiation/delithiation
process. In this paper, F<sup>–</sup> was chosen to replace
some of the benzenedicarboxylate (BDC) linkers because of its better
interaction with the Li<sup>+</sup> than the oxide ion. What’s
more, the formed M–F bond promotes the Li<sup>+</sup> to transfer
at the active material interface and protects the surface from HF
attacking. The as-synthesized F-doped Mn-MOF electrode maintains a
reversible capacity of 927 mA h g<sup>–1</sup> with capacity
retention of 78.5% after 100 cycles at 100 mA g<sup>–1</sup> and also exhibits a high discharge capacity of 716 mA h g<sup>–1</sup> at 300 mA g<sup>–1</sup> and 620 mA h g<sup>–1</sup> at 500 mA g<sup>–1</sup> after 500 cycles. Even at 1000 mA
g<sup>–1</sup>, the electrode still maintains a high reversible
capacity of 494 mA h g<sup>–1</sup> after 500 cycles as well
as a Coulombic efficiency of nearly 100%, which is drastically increased
compared with pure Mn-MOF material as expected
Synthesis of a PNIPAM-Based Composite Hydrogel and Its Multipurpose Applications in Piezoresistive and Temperature Sensing
Herein, a poly(N-isopropylacrylamide)-based
conductive
composite hydrogel system coenhanced by clay and polydopamine-modified
MXene was synthesized to achieve strain and temperature sensibility
simultaneously. The noncovalently cross-linked network via MXene,
clay, and polymer chains endowed the synthesized hydrogel with excellent
mechanical properties (tensile strength at a break of 117 kPa and
elongation at a break of 1723%). This hydrogel also exhibits strong
adhesion and good electrical conductivity (0.13 S/m). Regarding the
sensing properties, its temperature sensitivity is 2.749 °C–1, while its strain detection limit is as low as 0.05%.
Based on the unique characteristics of the prepared hydrogel, the
as-assembled sensor can detect stress and temperature simultaneously,
exhibiting great application potential in human physiological monitoring
Simple Synthesis of Amorphous NiWO<sub>4</sub> Nanostructure and Its Application as a Novel Cathode Material for Asymmetric Supercapacitors
This
study reports a simple synthesis of amorphous nickel tungstate
(NiWO<sub>4</sub>) nanostructure and its application as a novel cathode
material for supercapacitors. The effect of reaction temperature on
the electrochemical properties of the NiWO<sub>4</sub> electrode was
studied, and results demonstrate that the material synthesized at
70 °C (NiW-70) has shown the highest specific capacitance of
586.2 F g<sup>–1</sup> at 0.5 A g<sup>–1</sup> in a
three-electrode system. To achieve a high energy density, a NiW-70//activated
carbon asymmetric supercapacitor is successfully assembled by use
of NiW-70 and activated carbon as the cathode and anode, respectively,
and then, its electrochemical performance is characterized by cyclic
voltammetry and galvanostatic charge–discharge measurements.
The results show that the assembled asymmetric supercapacitor can
be cycled reversibly between 0 and 1.6 V with a high specific capacitance
of 71.1 F g<sup>–1</sup> at 0.25 A g<sup>–1</sup>, which
can deliver a maximum energy density of 25.3 Wh kg<sup>–1</sup> at a power density of 200 W kg<sup>–1</sup>. Furthermore,
this asymmetric supercapacitor also presented an excellent, long cycle
life along with 91.4% specific capacitance being retained after 5000
consecutive times of cycling
Casein Phosphopeptide-Biofunctionalized Graphene Biocomposite for Hydroxyapatite Biomimetic Mineralization
Casein
phosphopeptides (CPPs) with abundant phosphoserine clusters
can mediate hydroxyapatite (HA) nucleation and growth. In this work,
a new type of CPPs-biofuctionalized graphene composite was synthesized
by amidation reaction between CPPs and carboxyalated graphene (CGO).
When immersed in stimulated body fluid (1.5 × SBF) at 37 °C
for different periods, the CPPs layer on the composite facilitated
efficient interaction between the CGO surface and mineral ions, which
promoted HA nanoparticle formation and shortened mineralization time
in comparison with pristine CGO. The synthesis of the composite mimicked
the natural biomineralization of bone, demonstrating that CPPs can
effectively improve the bioactivity of graphene and be useful for
HA formation. The presented biocomposite may have potential biomedical
applications in different areas
Method for Measuring the Three-Dimensional Morphology of Near-Wall Bubbles and Droplets Based on LED Digital Holography
Digital holography, recognized for
its noncontact nature and high
precision in three-dimensional imaging, is effectively employed to
measure the morphology of bubbles and droplets. However, in terms
of near-wall bubbles and droplets, such as confined bubbles in microfluidic
chips, the measurement of the interface morphology of bubbles near
the glass surface has not yet been resolved due to the coherent noise
resulting from glass surface reflections in microfluidic chips. Accordingly,
an off-axis digital holography system was devised by using Linnik
interferometry. Measuring the confined bubble interface near the wall
within a microfluidic chip and droplet evaporation on solid surfaces
was studied. Partially coherent LED sources and reference light modulation
techniques were employed in the optical setup to mitigate the coherent
noise. Dual exposure and weighted least-squares unwrapping algorithms
were introduced to correct phase distortions, enhancing image quality.
Imaging two confined CO2 bubbles was done near the wall
in silicon oil within a porous microfluidic chip, and contact angles
of 4.7 and 4.5° were measured. Additionally, the measurement
of the three-dimensional morphology of vertically evaporating deionized
water droplets on a glass surface was done, due to which calculation
of contact angles at various orientations was possible. This work
offers a feasible new method for measuring the 3D interface morphology
of bubbles and droplets, particularly in microfluidic visualization,
addressing current measurement gaps