Highly Stable Polyaniline-Based Cathode Material Enabled by Phosphorene for Zinc-Ion Batteries with Superior Specific Capacity and Cycle Life.

Aqueous zinc-ion batteries (ZIBs) are regarded as a type of promising energy-storage device because of their high safety and low cost, and polyaniline (PANI) is normally employed as a cathode material for ZIBs owing to its unique electrochemical properties and high environmental stability. However, a low specific capacity and a short cycle life limit the development and applications of PANI-based electrodes. Herein, we have developed a novel type of highly stable PANI-based cathode material enabled by phosphene (PR) for aqueous Zn-PANI batteries through in situ chemical oxidative polymerization. The introduction of PR nanoflakes not only inhibits the degradation of PANI and generates more active sites for Zn2+ storage but also enables a synergistic effect of the Zn2+ insertion/extraction and P-Zn alloying reaction. This promotes a high reversible specific capacity of 240.2 mAh g-1 at 0.2 A g-1 and excellent rate performance for the PR/PANI nanocomposite cathode material. Compared to the pristine PANI cathode material, the PR/PANI nanocomposite cathode material is more suitable for the Zn-PANI battery, thanks to its higher specific capacity and better cycle stability. This study provides an innovative approach for developing the next generation of reliable PR-based electrode materials for aqueous energy-storage devices.

Chemical Vapor Transport Synthesis of Fibrous Red Phosphorus Crystal as Anodes for Lithium-Ion Batteries.

Red phosphorus (RP) is considered to be the most promising anode material for lithium-Ion batteries (LIBs) due to its high theoretical specific capacity and suitable voltage platform. However, its poor electrical conductivity (10-12 S/m) and the large volume changes that accompany the cycling process severely limit its practical application. Herein, we have prepared fibrous red phosphorus (FP) that possesses better electrical conductivity (10-4 S/m) and a special structure by chemical vapor transport (CVT) to improve electrochemical performance as an anode material for LIBs. Compounding it with graphite (C) by a simple ball milling method, the composite material (FP-C) shows a high reversible specific capacity of 1621 mAh/g, excellent high-rate performance and long cycle life with a capacity of 742.4 mAh/g after 700 cycles at a high current density of 2 A/g, and coulombic efficiencies reaching almost 100% for each cycle.

Significant differences in the electrochemical activity of black phosphorus anodes prepared under different atmospheres.

The effects of atmosphere and temperature on the electrochemical reversibility of black phosphorus (BP) anodes were investigated. BP anodes prepared in ambient air exhibited much-enhanced electrochemical activity due to the newly formed Cu3P phase. This work highlights the importance of maintaining intragranular electronic conduction for developing advanced BP-based anodes with high reversible capacities.

MXene Enhanced the Electromechanical Performance of a Nafion-Based Actuator.

Ionic electroactive polymer-based actuators have attracted much attention due to their low potential stimuli. In this work, MXene-Nafion composite actuators were fabricated, and the actuation performances were tested. The morphology of the as-made MXene-Nafion composite showed that the composite membrane was homogeneous, with an MXene doping level up to 5 wt%. In addition, the results of blocked force, response speed, and durability demonstrated that the actuation behavior of the composite-based actuator was enhanced due to the efficient dispersion of the two-dimensional nanofiller MXene. In addition, the blocking force of the composite actuator with a doping level of 0.5 wt% was about 6 times that of the pure Nafion without back-relaxation and durability degradation during the testing period.

Reduced Graphene Oxide-Polypyrrole Aerogel-Based Coaxial Heterogeneous Microfiber Enables Ultrasensitive Pressure Monitoring of Living Organisms.

Pressure sensors for living organisms can monitor both the movement behavior of the organism and pressure changes of the organ, and they have vast perspectives for the health management information platform and disease diagnostics/treatment through the micropressure changes of organs. Although pressure sensors have been widely integrated with e-skin or other wearable systems for health monitoring, they have not been approved for comprehensive surveillance and monitoring of living organisms due to their unsatisfied sensing performance. To solve the problem, here, we introduce a novel structural design strategy to manufacture reduced graphene oxide-polypyrrole aerogel-based microfibers with a typical coaxial heterogeneous structure, which significantly enhances the sensitivity, resolution, and stability of the derived pressure microsensors. The as-fabricated pressure microsensors exhibit ultrahigh sensitivities of 12.84, 18.27, and 4.46 kPa-1 in the pressure ranges of 0-20, 20-40, and 40-65 Pa, respectively, high resolution (0.2 Pa), and good stability in 450 cycles. Furthermore, the microsensor is applied to detect the movement behavior and organic micropressure changes for mice and serves as a platform for monitoring micropressure for the integrative diagnosis both in vivo and in vitro of organisms.

High Electrochemical Performance Phosphorus-Oxide Modified Graphene Electrode for Redox Supercapacitors Prepared by One-Step Electrochemical Exfoliation.

Phosphorus oxide modified graphene was prepared by one-step electrochemical anodic exfoliation method and utilized as electrode in a redox supercapacitor that contained potassium iodide in electrolytes. The whole preparation process was completed in a few minutes and the yield was about 37.2%. The prepared sample has better electrocatalysis activity for I−/I−3 redox reaction than graphite due to the good charge transfer performance between phosphorus oxide and iodide ions. The maximum discharge specific capacitance is 1634.2 F/g when the current density is 3.5 mA/cm² and it can keep at 463 F/g after 500 charging⁻discharging cycles when the current density increased about three times.

High Performance of Supercapacitor from PEDOT:PSS Electrode and Redox Iodide Ion Electrolyte.

Insufficient energy density and poor cyclic stability is still challenge for conductive polymer-based supercapacitor. Herein, high performance electrochemical system has been assembled by combining poly (3,4-ethylenedioxythiophene) (PEDOT):poly (styrene sulfonate) (PSS) redox electrode and potassium iodide redox electrolyte, which provide the maximum specific capacity of 51.3 mAh/g and the retention of specific capacity of 87.6% after 3000 cycles due to the synergic effect through a simultaneous redox reaction both in electrode and electrolyte, as well as the catalytic activity for reduction of triiodide of the PEDOT:PSS.

Ultra High Electrical Performance of Nano Nickel Oxide and Polyaniline Composite Materials.

The cooperative effects between the PANI (polyaniline)/nano-NiO (nano nickel oxide) composite electrode material and redox electrolytes (potassium iodide, KI) for supercapacitor applications was firstly discussed in this article, providing a novel method to prepare nano-NiO by using ß-cyelodextrin (ß-CD) as the template agent. The experimental results revealed that the composite electrode processed a high specific capacitance (2122.75 F·g-1 at 0.1 A·g-1 in 0.05 M KI electrolyte solution), superior energy density (64.05 Wh·kg-1 at 0.2 A·g-1 in the two-electrode system) and excellent cycle performance (86% capacitance retention after 1000 cycles at 1.5 A·g-1). All those ultra-high electrical performances owe to the KI active material in the electrolyte and the PANI coated nano-NiO structure.

Enhancement in Mechanical and Shape Memory Properties for Liquid Crystalline Polyurethane Strengthened by Graphene Oxide.

Conventional shape memory polymers suffer the drawbacks of low thermal stability, low strength, and low shape recovery speed. In this study, main-chain liquid crystalline polyurethane (LCPU) that contains polar groups was synthesized. Graphene oxide (GO)/LCPU composite was fabricated using the solution casting method. The tensile strength of GO/LCPU was 1.78 times that of neat LCPU. In addition, shape recovery speed was extensively improved. The average recovery rate of sample with 20 wt % GO loading was 9.2°/s, much faster than that of LCPU of 2.6°/s. The enhancement in mechanical property and shape memory behavior could be attributed to the structure of LCPU and GO, which enhanced the interfacial interactions between GO and LCPU.

New Supercapacitors Based on the Synergetic Redox Effect between Electrode and Electrolyte.

Redox electrolytes can provide significant enhancement of capacitance for supercapacitors. However, more important promotion comes from the synergetic effect and matching between the electrode and electrolyte. Herein, we report a novel electrochemical system consisted of a polyanilline/carbon nanotube composite redox electrode and a hydroquinone (HQ) redox electrolyte, which exhibits a specific capacitance of 7926 F/g in a three-electrode system when the concentration of HQ in H2SO4 aqueous electrolyte is 2 mol/L, and the maximum energy density of 114 Wh/kg in two-electrode symmetric configuration. Moreover, the specific capacitance retention of 96% after 1000 galvanostatic charge/discharge cycles proves an excellent cyclic stability. These ultrahigh performances of the supercapacitor are attributed to the synergistic effect both in redox polyanilline-based electrolyte and the redox hydroquinone electrode.

High Rate Performance Nanocomposite Electrode of Mesoporous Manganese Dioxide/Silver Nanowires in KI Electrolytes.

In recent years, manganese dioxide has become a research hotspot as an electrode material because of its low price. However, it has also become an obstacle to industrialization due to its low ratio of capacitance and the low rate performance which is caused by the poor electrical conductivity. In this study, a KI solution with electrochemical activity was innovatively applied to the electrolyte, and we systematically investigated the rate performance of the mesoporous manganese dioxide and the composite electrode with silver nanowires in supercapacitors. The results showed that when mesoporous manganese dioxide and mesoporous manganese dioxide/silver nanowires composite were used as electrodes, the strength of the current was amplified five times (from 0.1 to 0.5 A/g), the remaining rates of specific capacitance were 95% (from 205.5 down to 197.1 F/g) and 92% (from 208.1 down to 191.7 F/g) in the KI electrolyte, and the rate performance was much higher than which in an Na2SO4 electrolyte with a remaining rate of 25% (from 200.3 down to 49.1 F/g) and 60% (from 187.2 down to 113.1 F/g). The morphology and detail structure were investigated by Scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectrometry and Nitrogen adsorption-desorption isotherms. The electrochemical performance was assessed by cyclic voltammograms, galvanostatic charge/discharge and electrochemical impedance spectroscopy.

Preparation and Electrochemical Characterization of Mesoporous Polyaniline-Silica Nanocomposites as an Electrode Material for Pseudocapacitors.

Mesoporous polyaniline-silica nanocomposites with a full interpenetrating structure for pseudocapacitors were synthesized via the vapor phase approach. The morphology and structure of the nanocomposites were deeply investigated by scanning electron microscopy, infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis and nitrogen adsorption-desorption tests. The results present that the mesoporous nanocomposites possess a uniform particle morphology and full interpenetrating structure, leading to a continuous conductive polyaniline network with a large specific surface area. The electrochemical performances of the nanocomposites were tested in a mixed solution of sulfuric acid and potassium iodide. With the merits of a large specific surface area and suitable pore size distribution, the nanocomposite showed a large specific capacitance (1702.68 farad (F)/g) due to its higher utilization of the active material. This amazing value is almost three-times larger than that of bulk polyaniline when the same mass of active material was used.

A Bioinspired Swimming and Walking Hydrogel Driven by Light-Controlled Local Density.

A hydrogel exhibits a real-time depth-controllable swimming motion via light-mediated modulation of local density to mimic the volume changes found in the bladders of fish. Moreover, other motions, e.g., rolling, somersaulting, and bipedal-like walking, can also be realized by designing or combining gel shapes, and the location of light.

Synthesis and characterization of full interpenetrating structure mesoporous polycarbonate-silica spheres and p-phenylenediamine adsorption.

As a common used and hardly emulsified amorphous thermoplastic, the bisphenol-A polycarbonates were used as the polymer candidate to form a novel monodispersed sub-micrometer mesoporous polymer-silica spheres with full interpenetrating structure. The synthesis procedure was based on a modified sol-gel approach in which the polycarbonate was plasticized in advanced by the surfactant of polymer emulsion. The mesoporous spheres possess a perfect uniform particle size and the polymer-silica spheres are held together by permanent entanglement in three dimensions. The defined crystallization of the polycarbonate was occurred when it was entrapped in the silica laminated matrix due to the plasticizing effect of the surfactant, and directly affected the thermal stability of the mesoporous spheres. The specific surface areas and pore diameters of mesoporous sphere were affected by the mass content and crystallization behavior of the polycarbonate. The p-phenylenediamine was used as adsorbate to investigate the cationic organics adsorption ability of the mesoporous spheres. The results shown that the polycarbonate-silica possess a well adsorption capacity for p-phenylenediamine by virtue of two kinds of hydrogen bond, and the maximum adsorption capacity was nearly 7.5 times larger than that of the hollow mesoporous silica.

Ligand-assisted fabrication of hollow CdSe nanospheres via Ostwald ripening and their microwave absorption properties.

Hollow CdSe nanospheres were successfully synthesized by a ligand-assisted solvothermal method based on an Ostwald ripening mechanism. The hollow CdSe nanospheres were synthesized in benzyl alcohol under solvothermal conditions using Cd(Ac)2 and Se as the precursors, and tryptophan as a ligand. The resulting hollow structures consisted of small nanocrystallite building blocks. More importantly, the hollow CdSe nanospheres could be used as an excellent microwave absorber for cm- and mm-wave absorption, depending on the thickness of the absorber.

A non-canonical MEK/ERK signaling pathway regulates autophagy via regulating Beclin 1.

Autophagy-essential proteins are the molecular basis of protective or destructive autophagy machinery. However, little is known about the signaling mechanisms governing these proteins and the opposing consequences of autophagy in mammals. Here we report that a non-canonical MEK/ERK module, which is positioned downstream of AMP-activated protein kinase (AMPK) and upstream of tuberous sclerosis complex (TSC), regulates autophagy by regulating Beclin 1. Depletion of ERK partially inhibited autophagy, whereas specific inhibition on MEK completely inhibited autophagy. MEK could bypass ERK to promote autophagy. Basal MEK/ERK activity conferred basal Beclin 1 by preventing disassembly of mammalian target of rapamycin complex 1 (mTORC1) and mTORC2. Activation of MEK/ERK by AMPK upon autophagy stimuli disassembled mTORC1 via binding to and activating TSC but disassembled mTORC2 independently of TSC. Inhibition of mTORC1 or mTORC2 by transiently or moderately activated MEK/ERK caused moderately enhanced Beclin 1 resulting in cytoprotective autophagy, whereas inhibition of both mTORC1 and mTORC2 by sustained MEK/ERK activation caused strongly pronounced Beclin 1 leading to cytodestructive autophagy. Our findings thus propose that the AMPK-MEK/ERK-TSC-mTOR pathway regulation of Beclin 1 represents different thresholds responsible for a protective or destructive autophagy.

Akt regulates vitamin D3-induced leukemia cell functional differentiation via Raf/MEK/ERK MAPK signaling.

1,25-dihydroxyvitamin D3 (vitamin D3) induces differentiation of HL-60 human myeloid leukemia cells; however, the signaling mechanism governing these effects is not fully clear. Here, we show that vitamin D3 induced functional differentiation by Akt through Raf/MEK/ERK MAPK signaling. Vitamin D3 downregulated Akt, weakened Akt-Raf1 interaction, and subsequently activated the Raf/MEK/ERK MAPK pathway. Pharmacological inhibition of MEK/ERK crippled differentiation in response to vitamin D3. Ectopic overexpression of Akt inhibited MAPK signaling, downregulated cyclin-dependent kinase (CDK) inhibitors p21(Wip1/Cip1) and p27(Kip1) and blunted differentiation in response to vitamin D3 while knockdown of Akt by RNA interference gave reverse effects. Furthermore, knockdown of the CDK inhibitors by siRNA crippled the recruitment of retinoblastoma protein (Rb) from the Raf1-Rb complex and Rb hypophosphorylation, and abolished differentiation in response to vitamin D3. Vitamin D3-induced MAPK signaling mediated upregulation of the CDK inhibitors and Rb, disassociation of Raf1 and Rb, and dephosphorylation of Rb, resulting in Rb binding to transcription factor E2F1 and subsequent differentiation. Finally, knockdown of Rb by siRNA prevented vitamin D3-induced differentiation. Mutating Rb at Ser795 evokes its association with E2F1, indicating the critical role of Rb Ser795 in regulating cell differentiation. Taken together, our data suggest that vitamin D3-triggered differentiation of human myeloid leukemia cells depends on downregulation of Akt, which dissociates from Raf1 and activates MAPK signaling leading to CDK inhibitor upregulation, Raf1 disassociation from Rb, and Rb upregulation and hypophosphorylation coupled to E2F1 binding.

Vitamin D3 induces autophagy of human myeloid leukemia cells.

Vitamin D3 causes potent suppression of various cancer cells; however, significant supraphysiological concentrations of this compound are required for antineoplastic effects. Current combinatorial therapies with vitamin D3 are restricted to differentiation effects. It remains uncertain if autophagy is involved in vitamin D3 inhibition on leukemia cells. Here we show that besides triggering differentiation and inhibiting apoptosis, which was previously known, vitamin D3 triggers autophagic death in human myeloid leukemia cells. Inhibiting differentiation does not efficiently diminish vitamin D3 suppression on leukemia cells. Vitamin D3 up-regulates Beclin1, which binds to class III phosphatidylinositol 3-kinase to trigger autophagy. Vitamin D3 phosphorylates Bad in its BH3 domain, resulting in disassociation of the apoptotic Bad-Bcl-xL complex and association of Bcl-xL with Beclin1 and ultimate suppression of apoptotic signaling. Knockdown of Beclin1 eliminates vitamin D3-induced autophagy and inhibits differentiation but activates apoptosis, suggesting that Beclin1 is required for both autophagy and differentiation, and autophagy cooperates with differentiation but excludes apoptosis, in which Beclin1 acts as an interface for these three different cascades. Moreover, additional up-regulation of autophagy, but not apoptosis, dramatically improves vitamin D3 inhibition on leukemia cells. These findings extend our understanding of the action of vitamin D3 in antineoplastic effects and the role of Beclin1 in regulating multiple cellular cascades and suggest a potentially promising strategy with a significantly better antileukemia effect.