1D Carbon-Based Nanocomposites for Electrochemical Energy Storage.

Electrochemical energy storage (EES) devices have attracted immense research interests as an effective technology for utilizing renewable energy. 1D carbon-based nanostructures are recognized as highly promising materials for EES application, combining the advantages of functional 1D nanostructures and carbon nanomaterials. Here, the recent advances of 1D carbon-based nanomaterials for electrochemical storage devices are considered. First, the different categories of 1D carbon-based nanocomposites, namely, 1D carbon-embedded, carbon-coated, carbon-encapsulated, and carbon-supported nanostructures, and the different synthesis methods are described. Next, the practical applications and optimization effects in electrochemical energy storage devices including Li-ion batteries, Na-ion batteries, Li-S batteries, and supercapacitors are presented. After that, the advanced in situ detection techniques that can be used to investigate the fundamental mechanisms and predict optimization of 1D carbon-based nanocomposites are discussed. Finally, an outlook for the development trend of 1D carbon-based nanocomposites for EES is provided.

Methyl-functionalized MoS2 nanosheets with reduced lattice breathing for enhanced pseudocapacitive sodium storage.

Sodium ion batteries (SIBs) possess the potential to realize low-cost and large-scale energy storage due to the abundance of sodium. However, the large ionic radius of sodium often leads to sluggish kinetics and large volume change, limiting the further development of SIBs. Layered MoS2, with a large interlayer distance, is a promising intercalation anode material for SIBs. In this work, we report the synthesis of methyl-functionalized MoS2 (M-MoS2) nanosheets through a facile second solvothermal method. During the second solvothermal treatment, the pristine MoS2 is mostly converted from the 2H to 1T phase and the interlayer distance is expanded from 0.65 to 0.80 nm. When evaluated as the anode for SIBs, the M-MoS2 exhibits superior cycling stability and rate capability. Kinetic analysis shows that the capacity is mainly contributed from a pseudocapacitive process. Ex situ XRD shows that the M-MoS2 exhibits inhibited lattice breathing and thus reduced volume change during cycling. This work demonstrates that the M-MoS2 is a promising candidate for pseudocapacitive sodium storage.

The role of TRPV4 in the regulation of retinal ganglion cells apoptosis in rat and mouse.

Retinal ganglion cell (RGC) damages are common in glaucoma, causing atrophy of the optic papilla, visual field damage, and visual loss. Transient receptor potential vanilloid 4 (TRPV4) is significantly expressed in the eyeball and is sensitive to mechanical and osmotic pressure. However, the specific role and mechanism of TRPV4 in glaucoma and RGC progression remain unclear. TRPV4 expression was detected in RGCs under different pressure culture conditions. We also explored the pressure effect on TRPV4 expression and the role and mechanism behind the functional regulation of RGCs. Immunofluorescence staining, western blotting, and TUNEL were utilized in this study. Our results established that TRPV4 was expressed in RGCs. TRPV4 expression was decreased at 40 mmHg and 60 mmHg, and the expression of BAX at 40 mmHg, 60 mmHg. Additionally, the expression of caspase 9 protein increased at 40 mmHg with the pressure increase compared with the conventional culture group. TUNEL staining revealed that the apoptosis rate of RGCs was elevated at 40 mmHg and 60 mmHg, compared with the traditional culture group. Therefore, the expression of BAX and caspase 9 increased, along with the apoptosis rate of RGCs compared with the control group. However, after TRPV4 antagonist treatment, the expression of BAX and caspase 9 decreased, and the apoptosis rate of RGCs decreased. Thus, TRPV4 may affect the mitochondrial apoptosis pathway, such as BAX and caspase 9, leading to the apoptosis of RGCs. The antagonists of TRPV4 could provide a new idea for clinically treating acute glaucoma.

Anchoring ultra-small Mo2C nanocrystals on honeycomb-structured N-doped carbon spheres for efficient hydrogen evolution.

Molybdenum carbide (Mo2C) has attracted considerable research interest as one of the most efficient non-noble electrocatalysts for the hydrogen evolution reaction (HER). Supporting nanosized Mo2C on a conductive carbon matrix with high porosity and large surface area represents an efficient strategy to enhance its HER performance. Herein, we constructed a Mo2C based HER catalyst consisting of ultra-small Mo2C nanocrystals anchored on honeycomb-structured N-doped carbon spheres (Mo2C-HNCS). The as-prepared Mo2C-HNCS manifests a high HER catalytic activity in alkaline media with an overpotential of 128 mV at 10 mA cm-2, a Tafel slope of 60 mV decade-1, and good stability.

Cobalt decorated nitrogen-doped carbon bowls as efficient electrocatalysts for the oxygen reduction reaction.

Cobalt decorated nitrogen-doped carbon bowls (Co@NCB) have been successfully constructed by impregnating bowl-like resin particles with cobalt salt followed by annealing. The cobalt exists in the following two forms in the obtained Co@NCB: Co nanoparticles and CoN4. The Co@NCB outperforms the commercial Pt/C in the oxygen reduction reaction in terms of half-wave potential and stability. When Co@NCB is applied in zinc-air batteries, a high open-circuit voltage, excellent power density, and satisfactory stability are achieved.

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-1 even after 1000 cycles at 1 A g-1. 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-1 after 300 cycles at 0.2 A g-1. This study suggests that the rational design of metal silicates would render them promising anode materials for LIBs and SIBs.

Mass Production of Monodisperse Carbon Microspheres with Size-Dependent Supercapacitor Performance via Aqueous Self-Catalyzed Polymerization.

A facile, aqueous, self-catalyzed polymerization method has been developed for the mass production of monodisperse phenolic resin and carbon microspheres. The synthesis is mainly based on the self-catalyzed reaction between phenol derivatives and the hydrolysis products of hexamethylenetetramine (HMTA). The obtained phenolic resin spheres have a tunable size of 0.8-6.0 µm, depending on the type of phenol and HMTA/phenol ratio. Treating the phenolic resin with steam at an elevated temperature results in monodisperse carbon microspheres with abundant micropores, high surface area, and rich surface functionality. The resultant carbon spheres exhibit a size-dependent electrical double-layer capacitor performance; the capacitance increases with decreasing particle size. The nitrogen and oxygen codoped carbon spheres with the smallest size (≈600 nm) deliver a high specific capacitance (282 F g-1 at 0.5 A g-1 ), excellent rate capability (170 F g-1 at 20 A g-1 ), and outstanding cycling stability (95.3 % capacitance retention after 10 000 cycles at 5 A g-1 ). This study provides a new avenue for the mass production of monodisperse carbon microspheres.

Facet-Selective Deposition of FeOx on α-MoO3 Nanobelts for Lithium Storage.

One-dimensional heterostructures have attracted significant interests in various applications. However, the selective deposition of shell material on specific sites of the backbone material remains a challenge. Herein, a facile facet-selective deposition strategy has been developed for the construction of heterostructured α-MoO3@FeOx nanobelts. Because of the anisotropic feature of α-MoO3 nanobelts, the FeOx nanoparticles selectively deposit on the edges of α-MoO3 nanobelts, that is, the {100} and {001} facets. Such a heterostructure facilitates the electron transfer in lithium storage. As a result, the α-MoO3@FeOx nanobelts exhibit high capacities of 913 mA h g-1 after 100 cycles at 200 mA g-1 and 540 mA h g-1 after 100 cycles at 1000 mA g-1. The facet-selective deposition strategy developed here would be extended to the construction of other novel heterostructures with fascinating physical/chemical properties and wide potential applications.

Low-crystalline iron oxide hydroxide nanoparticle anode for high-performance supercapacitors.

Carbon materials are generally preferred as anodes in supercapacitors; however, their low capacitance limits the attained energy density of supercapacitor devices with aqueous electrolytes. Here, we report a low-crystalline iron oxide hydroxide nanoparticle anode with comprehensive electrochemical performance at a wide potential window. The iron oxide hydroxide nanoparticles present capacitances of 1,066 and 716 F g-1 at mass loadings of 1.6 and 9.1 mg cm-2, respectively, a rate capability with 74.6% of capacitance retention at 30 A g-1, and cycling stability retaining 91% of capacitance after 10,000 cycles. The performance is attributed to a dominant capacitive charge-storage mechanism. An aqueous hybrid supercapacitor based on the iron oxide hydroxide anode shows stability during float voltage test for 450 h and an energy density of 104 Wh kg-1 at a power density of 1.27 kW kg-1. A packaged device delivers gravimetric and volumetric energy densities of 33.14 Wh kg-1 and 17.24 Wh l-1, respectively.

Alkaline earth metal vanadates as sodium-ion battery anodes.

The abundance of sodium resources indicates the potential of sodium-ion batteries as emerging energy storage devices. However, the practical application of sodium-ion batteries is hindered by the limited electrochemical performance of electrode materials, especially at the anode side. Here, we identify alkaline earth metal vanadates as promising anodes for sodium-ion batteries. The prepared calcium vanadate nanowires possess intrinsically high electronic conductivity (> 100 S cm-1), small volume change (< 10%), and a self-preserving effect, which results in a superior cycling and rate performance and an applicable reversible capacity (> 300 mAh g-1), with an average voltage of ∼1.0 V. The specific sodium-storage mechanism, beyond the conventional intercalation or conversion reaction, is demonstrated through in situ and ex situ characterizations and theoretical calculations. This work explores alkaline earth metal vanadates for sodium-ion battery anodes and may open a direction for energy storage.The development of suitable anode materials is essential to advance sodium-ion battery technologies. Here the authors report that alkaline earth metal vanadates are promising candidates due to the favorable electrochemical properties and interesting sodium-storage mechanism.

Self-adaptive strain-relaxation optimization for high-energy lithium storage material through crumpling of graphene.

High-energy lithium battery materials based on conversion/alloying reactions have tremendous potential applications in new generation energy storage devices. However, these applications are limited by inherent large volume variations and sluggish kinetics. Here we report a self-adaptive strain-relaxed electrode through crumpling of graphene to serve as high-stretchy protective shells on metal framework, to overcome these limitations. The graphene sheets are self-assembled and deeply crumpled into pinecone-like structure through a contraction-strain-driven crumpling method. The as-prepared electrode exhibits high specific capacity (2,165 mAh g(-1)), fast charge-discharge rate (20 A g(-1)) with no capacity fading in 1,000 cycles. This kind of crumpled graphene has self-adaptive behaviour of spontaneous unfolding-folding synchronized with cyclic expansion-contraction volumetric variation of core materials, which can release strain and maintain good electric contact simultaneously. It is expected that such findings will facilitate the applications of crumpled graphene and the self-adaptive materials.