Abstract
Real-time sensing of nitric oxide (NO) in physiological environments is critically important in monitoring neurotransmission, inflammatory responses, cardiovascular systems, etc. ...Conventional approaches for NO detection relying on indirect colorimetric measurement or built with rigid and permanent materials cannot provide continuous monitoring and/or require additional surgical retrieval of the implants, which comes with increased risks and hospital cost. Herein, we report a flexible, biologically degradable and wirelessly operated electrochemical sensor for real-time NO detection with a low detection limit (3.97 nmol), a wide sensing range (0.01–100 μM), and desirable anti-interference characteristics. The device successfully captures NO evolution in cultured cells and organs, with results comparable to those obtained from the standard Griess assay. Incorporated with a wireless circuit, the sensor platform achieves continuous sensing of NO levels in living mammals for several days. The work may provide essential diagnostic and therapeutic information for health assessment, treatment optimization and postsurgical monitoring.
Three-dimensional flower-like and hierarchical porous carbon material (FHPC) has been fabricated through a simple and efficient carbonization method followed by chemical activation with flower-like ...ZnO as template and pitch as carbon precursor. The hierarchical porous structure is composed of numerous micropores and well-defined mesopores in the interconnected macroporous walls. The FHPC electrode can achieve a relatively high capacitance of 294Fg−1 at a scan rate of 2mVs−1 and excellent rate capability (71% retention at 500mVs−1) with superior cycle stability (only 2% loss after 5000 cycles) in 6molL−1 KOH electrolyte. The symmetric supercapacitor fabricated with FHPC electrodes delivers a high energy density of 15.9Whkg−1 at a power density of 317.5Wkg−1 operated in the voltage range of 0–1.8V in 1molL−1 Na2SO4 aqueous electrolyte.
A graphene nanosheet (GNS)/polyaniline (PANI) composite was synthesized using
in situ polymerization. The morphology and microstructure of samples were examined by scanning electron microscopy (SEM), ...transition electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. Electrochemical properties were characterized by cyclic voltammetry (CV) and galvanostatic charge/discharge. GNS as a support material could provide more active sites for nucleation of PANI as well as excellent electron transfer path. The GNS was homogeneously coated on both surfaces with PANI nanoparticles (∼2
nm), and a high specific capacitance of 1046
F
g
−1 (based on GNS/PANI composite) was obtained at a scan rate of 1
mV
s
−1 compared to 115
F
g
−1 for pure PANI. In addition, the energy density of GNS/PANI composite could reach 39
W
h
kg
−1 at a power density of 70
kW
kg
−1.
Three‐dimensional carbon nanotube/graphene sandwich structures with CNT pillars grown in between the graphene layers have been developed by chemical vapor deposition. The special structure endows the ...high‐rate transportation of electrolyte ions and electrons throughout the electrode matrix, resulting in excellent electrochemical performance of this hybrid material.
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•NiCo2S4@CoMoO4 core-shell heterostructure nanowire arrays are prepared as flexible supercapacitor electrode.•The NiCo2S4@CoMoO4 electrode exhibits remarkable specific capacitance and ...high-rate capability.•A flexible all-solid-state ACS device based on NiCo2S4@CoMoO4 is fabricated.
In order to meet the application requirements of portable and wearable devices, the high-efficiency energy storage units with high energy density, high power density and long cycle life are urgently needed. In this work, we have successfully fabricated novel flexible electrode comprising NiCo2S4@CoMoO4 core–shell nanowire arrays on carbon cloth via a facile three-step hydrothermalprocess. Benefiting from the unique hierarchical structure and their synergistic effects between CoMoO4 and NiCo2S4, the supercapacitor electrode realizes a fast electron and ion transfer, a large electroactive surface area and superior conductivity. As a result, the NiCo2S4@CoMoO4 electrode exhibits superior performances with an outstanding specific capacitance of 2118.8 F g−1 at 1 A g−1 and an excellent rate capability of 81.6% at 20 A g−1. After 5000 cycles, the NiCo2S4@CoMoO4 electrode shows an excellent cyclic performance with 88.6% capacity retention. The excellent performance of electrode is also confirmed by assembling all-solid-state asymmetric supercapacitor, which delivers a high energy density of 66.6 Wh kg−1 as well as the maximum power density of 16 kW kg−1. This work demonstrates that the NiCo2S4@CoMoO4 electrode provides a promising material for the energy storage applications in the future.
The effects of combined addition of Y and Ce on the microstructure, mechanical properties and anisotropy of as-rolled Mg-8Li-1Al (LA81) alloy were studied. The combined addition of Y and Ce improves ...the mechanical properties with a low plasticity loss by solution strengthening, dispersion strengthening, grain refinement strengthening. Mg-8Li-1Al-0.6Y-0.6Ce (LA81-0.6Y-0.6Ce) has better mechanical properties and shows an almost isotropy. It possesses an ultimate tensile strength of 278.7 MPa and an elongation of 15.0%. Compared to LA81 alloy, the ultimate tensile strength increases by about 17.6% with an elongation reduction of only 3.5%, and a good isotropy of ultimate tensile strength and elongation (the value of ravg is near 1).
Graphene nanosheet/carbon nanotube/polyaniline (GNS/CNT/PANI) composite is synthesized via in situ polymerization. GNS/CNT/PANI composite exhibits the specific capacitance of 1035
F
g
−1 (1
mV
s
−1) ...in 6
M of KOH, which is a little lower than GNS/PANI composite (1046
F
g
−1), but much higher than pure PANI (115
F
g
−1) and CNT/PANI composite (780
F
g
−1). Though a small amount of CNTs (1
wt.%) is added into GNS, the cycle stability of GNS/CNT/PANI composite is greatly improved due to the maintenance of highly conductive path as well as mechanical strength of the electrode during doping/dedoping processes. After 1000 cycles, the capacitance decreases only 6% of initial capacitance compared to 52% and 67% for GNS/PANI and CNT/PANI composites.
A green and facile approach was demonstrated to prepare graphene nanosheets/ZnO (GNS/ZnO) composites for supercapacitor materials. Glucose, as a reducing agent, and exfoliated graphite oxide (GO), as ...precursor, were used to synthesize GNS, then ZnO directly grew onto conducting graphene nanosheets as electrode materials. The small ZnO particles successfully anchored onto graphene sheets as spacers to keep the neighboring sheets separate. The electrochemical performances of these electrodes were analyzed by cyclic voltammetry, electrochemical impedance spectrometry and chronopotentiometry. Results showed that the GNS/ZnO composites displayed superior capacitive performance with large capacitance (62.2
F/g), excellent cyclic performance, and maximum power density (8.1
kW/kg) as compared with pure graphene electrodes. Our investigation highlight the importance of anchoring of small ZnO particles on graphene sheets for maximum utilization of electrochemically active ZnO and graphene for energy storage application in supercapacitors.
Glucose was used to synthesize GNS, then ZnO directly grew onto conducting graphene nanosheets as electrode materials for supercapacitor. Results showed that the composites have superior capacitive performance.
▪
► Graphene nanosheets were synthesized via using glucose as a reducing agent. ► The reductant and the oxidized product are environmentally friendly. ► ZnO grew onto conducting graphene sheets keeping neighboring sheets separate. ► The structure improves the contact between the electrode and the electrolyte. ► Results showed that these composites have good electrochemical property.
Here we present a facile and efficient process for the preparation of Fe3O4 nanoparticles (about an average diameter of 5nm) grown on reduced graphene oxide (Fe3O4/rGO) with high supercapacitive ...properties. The novel composite with high surface area and mesoporous structure are prepared by a one-step hydrothermal method with the help of glucose, which can serve as a binder for the assembly of Fe3O4 nanoparticles (NPs) and a reducing agent for the reduction of graphene oxide simultaneously. Benefiting from the combined rGO and Fe3O4 in such a unique structure, the Fe3O4/rGO electrode material possesses a high specific capacitance of 241F/g at 1A/g within the potential range from -1 to 0V and an excellent cycling stability of 79.2% after 1000 cycles at a high current density of 10A/g. These results demonstrate that such synthetic route may open a new pathway to design and fabricate other materials with largely enhanced electrochemical properties, which can be of great potential in the development of energy-storage systems.
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