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.
Higher strength is always the goal pursued by researchers for the structural materials, especially for the lightweight magnesium (Mg) alloys which generally have relatively low strength at present. ...From this aspect, the present paper reviews the recent reports of a kind of Mg alloys, i.e. Mg-RE (RE: rare earths, mainly Gd or Y) casting and wrought alloys, which have been able to achieve high strength compared with common or commercial Mg alloys, from the viewpoint and content of the alloy system, alloying constitution, preparation process, tensile strength and each of the main strengthening mechanisms. This review of recent research and developments in high-strength Mg-RE alloys is beneficial for the further design of Mg alloys with higher strength as well as excellent comprehensive performance.
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.
We demonstrated the fabrication of functionalized graphene nanosheets via low temperature (300 °C) treatment of graphite oxide with a slow heating rate using Mg(OH)2 nanosheets as template. Because ...of its dented sheet with high surface area, a certain amount of oxygen-containing groups, and low pore volume, the as-obtained graphene delivers both ultrahigh specific gravimetric and volumetric capacitances of 456 F g–1 and 470 F cm–3, almost 3.7 times and 3.3 times higher than hydrazine reduced graphene, respectively. Especially, the obtained volumetric capacitance is the highest value so far reported for carbon materials in aqueous electrolytes. More importantly, the assembled supercapacitor exhibits an ultrahigh volumetric energy density of 27.2 Wh L–1, which is among the highest values for carbon materials in aqueous electrolytes, as well as excellent cycling stability with 134% of its initial capacitance after 10 000 cycles. Therefore, the present work holds a great promise for future design and large-scale production of high performance graphene electrodes for portable energy storage devices.
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.
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