Sodium ion batteries (NIBs) have become attractive promising alternatives to lithium ion batteries in a broad field of future energy storage applications. The development of high‐performance anode ...materials has become an essential factor and a great challenge toward satisfying the requirements for NIBs, advancement. This work is the first report on GeS2 nanocomposites uniformly distributed on reduced graphene oxide (rGO) as promising anode materials for NIBs prepared via a facile hydrothermal synthesis and a unique carbo‐thermal annealing. The results show that the GeS2/rGO hybrid anode yields a high reversible specific capacity of 805 mA h g−1 beyond the theoretical capacity, an excellent rate capability of 616 mA h g−1 at 5 A g−1, and a cycle retention of 89.4% after 100 cycles. A combined ex situ characterization study reveals that the electrochemically driven amorphization plays a key role in achieving efficient sodium storage by accommodating excess sodium ions in the electrode materials. Understanding the sequential conversion‐alloying reaction mechanism for GeS2/rGO hybrid anodes provides a new approach for developing high‐performance energy storage applications.
The novel‐designed GeS2/rGO hybrid anode materials are prepared via a facile hydrothermal synthesis and a unique carbo‐thermal annealing. The nanocomposites ensure the high reversible specific capacity of 805 mA h g−1 beyond the theoretical capacity and the excellent rate capability (562 mA h g−1 at 5 A g−1), revealing the best use of electrochemically driven amorphization.
A new direction for developing electrocatalysts for hydrogen fuel cell systems has emerged, based on the fabrication of 3D architectures. These new architectures include extended Pt surface building ...blocks, the strategic use of void spaces, and deliberate network connectivity along with tortuosity, as design components. Various strategies for synthesis now enable the functional and structural engineering of these electrocatalysts with appropriate electronic, ionic, and electrochemical features. The new architectures provide efficient mass transport and large electrochemically active areas. To date, although there are few examples of fully functioning hydrogen fuel cell devices, these 3D electrocatalysts have the potential to achieve optimal cell performance and durability, exceeding conventional Pt powder (i.e., Pt/C) electrocatalysts. This progress report highlights the various 3D architectures proposed for Pt electrocatalysts, advances made in the fabrication of these structures, and the remaining technical challenges. Attempts to develop design rules for 3D architectures and modeling, provide insights into their achievable and potential performance. Perspectives on future developments of new multiscale designs are also discussed along with future study directions.
3D Pt architectures have received tremendous attention owing to their superior structure and intrinsic properties, and are suited to fuel cell electrocatalyst applications. The fabrication methods and the effect of geometry on electrochemical processes for high‐performance 3D Pt electrocatalysts are reviewed. New design guidelines for the development of such electrocatalysts are proposed, considering future research directions.
Abstract
The present study investigates the fabrication of hierarchical 3D nanostructures with multi-component metal oxides in the presence of highly-porous graphene and characterized for its ...applications in high-performance supercapacitors. A hierarchical flowers like 3D nanostructure of Co
3
O
4
@MnO
2
on nitrogen-doped graphene oxide (NGO) hybrid composite was synthesized by thermal reduction process at 650 °C in the presence of ammonia and urea. The synthesized Co
3
O
4
@MnO
2
/NGO hybrid composites were studied
via
Raman, XRD, X-ray XPS, FE-SEM, FE-SEM with EDX, FE-TEM and BET analyses. The electrochemical analysis of Co
3
O
4
@MnO
2
/NGO hybrid composite electrode was investigated using cyclic voltammetry, chronopotentiometry and electrochemical impedance measurements. The hybrid composite electrode showed significant specific capacitance results of up to 347 F/g at 0.5 A/g and a corresponding energy density of 34.83 Wh kg
−1
with better rate performance and excellent long-term cycling stability were achieved for 10,000 cycles. The obtained electrochemical results paved a way to utilize Co
3
O
4
@MnO
2
/NGO composite electrode as a promising electrode material in high performance supercapacitors.
Nanostructural design renders several breakthroughs for the construction of high-performance materials and devices including energy-storage systems. Although attempts made toward electrode ...engineering have improved the existing drawbacks, nanoengineering is still hindered by some issues. To achieve practical applications of lithium–sulfur (Li–S) batteries, it is difficult to attain a high areal capacity with stable cycling. Physical encapsulation via nanostructural design not only can resolve the issue of lithium polysulfide dissolution during the electrochemical cycling, but also can offer significant contact resistance, which in turn can decrease the kinetics, particularly at a high sulfur loading. Thus, we demonstrate an electrospun carbon nanofiber (CNF) matrix for a sulfur cathode. This simple design enables a high mass loading of 10.5 mg cm–2 with a high specific capacity and stable cycling. The CNF–sulfur complex can deliver a high areal capacity of greater than 7 mAh cm–2, which is related to the excellent electrical conductivity of one-dimensional species. Moreover, we have observed that the reacted sulfur species have adhered well to the junction of the CNF network with specific wetting angles, which are induced by the cohesive force between the narrow gaps in the matrix that trapped the viscous polysulfides during cycling. The results of this study open new avenues for the design of high-areal-capacity Li–S batteries.
A continuous operating pre-concentrator for trace gas analysis was developed and introduced for specific applications that can achieve a significant increase in trace gas concentrations using ...relative simple mass diffusion separation stages, without interrupting the gas flows. The pre-concentrator, which can be useful in the detection of the real-time variations in the concentration of trace gases, required less operational time. The prototype of a pre-concentrator designed as a macroscale device, which used the physical properties of the molecules and room temperature, was applied to two different polycarbonate membranes to examine the effects of porosity and the transmission probability. The concentration ratios of trace gases obtained by the experiment did not increase significantly, as predicted by the theoretical model. However, the experimental results showed that a prototype pre-concentrator can be used to obtain an increase in trace gas concentration within tens of seconds.
Display omitted
•Experimental investigation of continuously operating pre-concnetrator in free molecular flow (Kn>1).•Gas separation by physical properties such as pressure difference and gas molecular weight ratio between carrier and trace gases.•Variation of concentration ratio of trace gases independent of material properties of separation membranes.
A single-ended transmitter achieves low power consumption with an integrated voltage modulation (IVM) scheme for memory interfaces. The transmitter preserves the power advantages of the ground ...(VSS)-terminated single-ended signaling by consuming no static power when transmitting logic-0s before the last bit of consecutive logic-0s (CLZs). All the intersymbol interference (ISI) accumulated during CLZs is compensated at once by the proposed IVM, which provides the unit interval (UI) spaced compensation voltage during the period of the last logic-0. The equalization, combining four-tap IVM and two-tap pull-up feed-forward equalization (FFE), allows the transmitter to be energy efficient without degrading the compensation effect. Per-UI basis IVM also has better immunity to noise and process, supply voltage, and temperature (PVT) variations than conventional phase equalization and pulsewidth modulation. The compensation effect and power consumption of IVM are also mathematically analyzed and compared with other conventional equalizations. A prototype chip fabricated in 65-nm CMOS has an area of 0.0168 mm2 and achieves a data rate of 16 Gb/s/pin over a transmission channel with −12.6 dB loss, with an energy efficiency of 0.85 pJ/bit.
Summary
Co3O4/RuO2@nitrogen‐doped graphene oxide (NGO) composite materials were synthesized through a sonication‐assisted thermal reduction method in the presence of cobalt and ruthenium starting ...reagents for supercapacitor and gas sensor applications. The composite materials were characterized using various analytical tools to confirm the structural and morphological properties. The synthesized Co3O4/RuO2@NGO composites showed the nanostructured grains anchored on the NGO surface. The electrochemical storage performance was studied by using cyclic voltammetry, galvanostatic charge discharge, and electrochemical impedance spectroscopy using a two‐electrode asymmetric configuration. The prepared Co3O4/RuO2@NGO electrode exhibited a maximum capacitance of ~149 F/g at an applied current of ~0.5 A/g, an energy density of 20.69 Wh kg−1, and at a power density of 250 W kg−1. The cycling behavior of the fabricated asymmetric capacitor revealed a 90% capacitance retention after 5000 cycles. Moreover, the prepared composite material was used successfully for dimethyl methylophosphonate (DMMP) vapor detection, showing excellent sensitivity, selectivity, and stability. Therefore, the constructed Co3O4/RuO2@NGO composite is a suitable material for supercapacitors and DMMP gas‐detection applications.
Co3O4/RuO2@nitrogen doped graphene oxide (NGO) composite materials were synthesized through a sonication assisted thermal reduction method. From the supercapacitive and gas sensing performance tests, the novel composite shows the feasibility for supercapacitors and DMMP gas detection applications.
Mitophagy is activated by a number of stimuli, including hypoxia, energy stress, and increased oxidative phosphorylation activity. Mitophagy is associated with oxidative stress conditions and central ...neurodegenerative diseases. Proper regulation of mitophagy is crucial for maintaining homeostasis; conversely, inadequate removal of mitochondria through mitophagy leads to the generation of oxidative species, including reactive oxygen species and reactive nitrogen species, resulting in various neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. These diseases are most prevalent in older adults whose bodies fail to maintain proper mitophagic functions to combat oxidative species. As mitophagy is essential for normal body function, by targeting mitophagic pathways we can improve these disease conditions. The search for effective remedies to treat these disease conditions is an ongoing process, which is why more studies are needed. Additionally, more relevant studies could help establish therapeutic conditions, which are currently in high demand. In this review, we discuss how mitophagy plays a significant role in homeostasis and how its dysregulation causes neurodegeneration. We also discuss how combating oxidative species and targeting mitophagy can help treat these neurodegenerative diseases.
Review of nanocellulose for sustainable future materials Kim, Joo-Hyung; Shim, Bong Sup; Kim, Heung Soo ...
International journal of precision engineering and manufacturing-green technology,
04/2015, Volume:
2, Issue:
2
Journal Article
Open access
Cellulose, the chain of glucose residues easily obtained from nature, is the most common natural polymer. Owing to its own unique material properties, compared to the conventional usage, ...nanocellulose (NC) with a crystalline structure can be considered to be used in various industrial applications. As a novel sustainable future material, we review the recent achievements of NC from the view point of material extraction and the composite processes to some extended important applications. While the mechanical properties of NCs and the energy consumption during their composite processing are the key considerations, their application potentials have never been limited to mechanical or commodity products as conventional celluloses. In the latter part of this review, emerging engineering applications of NCs such as energy storage, flexible electronics, and smart materials will be further discussed for readers searching future high-end eco-friendly functional materials. Also some suggestions for potential applications will be also discussed.
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