Search

The high-cost synthesis of highly dispersed non-noble metal–nitrogen–carbon (MNC) electrocatalysts hinders their practical applications. Here, we have developed a cost/time-efficient synthesis method for MNC electrocatalysts with highly dispersed metal sites, using the commercially available cheap ZnO as the Zn source, reducing the cost of Zn usage by over 80%. Our specially chosen solvent formamide can react with ZnO and allow the formation of nano-sized ZnFeCo–Nx complexes uniformly distributed in the formamide-derived high-N-doped carbon substrate. Further annealing the ZnFeCo–N–C precursor will produce a highly dispersed FeCo–NC target product. Electrochemical measurements show that the prepared FeCo–NC is an excellent electrocatalyst for alkaline oxygen reduction reaction (ORR), rendering superior onset and half-wave potentials of 1.05 and 0.92 V, respectively. The Al–air battery assembled using this also shows a high specific power (204.9 mW cm−2) and a large specific capacity (552 mA h g−1 at 10 mA cm−2), exceeding those of the 20 wt% Pt/C catalyst. Our method may inspire the scalable and low-cost production of highly dispersed MNC electrocatalysts and their wide range of practical applications.

Lactate and isoprene are two common monomers for the industrial production of polyesters and synthetic rubbers. The present study tested the co-production of D-lactate and isoprene by engineered Escherichia coli in microaerobic conditions. The deletion of alcohol dehydrogenase (adhE) and acetate kinase (ackA) genes, along with the supplementation with betaine, improved the co-production of lactate and isoprene from the substrates of glucose and mevalonate. In fed-batch studies, microaerobic fermentation significantly improved the isoprene concentration in fermentation outlet gas (average 0.021 g/L), compared with fermentation under aerobic conditions (average 0.0009 g/L). The final production of D-lactate and isoprene can reach 44.0 g/L and 3.2 g/L, respectively, through fed-batch microaerobic fermentation. Our study demonstrated a dual-phase production strategy in the co-production of isoprene (gas phase) and lactate (liquid phase). The increased concentration of gas-phase isoprene could benefit the downstream process and decrease the production cost to collect and purify the bio-isoprene from the fermentation outlet gas. The proposed microaerobic process can potentially be applied in the production of other volatile bioproducts to benefit the downstream purification process.

Carbide-derived carbons (CDC) represent a kind of typical and fascinating porous carbon materials (PCM) for broad applications but demand hazardous chlorine to fulfil the conversion into carbon. Here in this study, we report the facile fabrication of PCM with rich porosity from mild molten alkaline-treated calcium carbide (CaC2). Resulted PCM under optimized synthesis conditions exhibited large specific surface area (∼839 m2 g−1) and specific capacitance (403 F g−1 at current density of 0.5 A g−1). Meanwhile, fairly good rate capability of retaining over 63% capacitance at large current density of 5 A g−1, and robust cycling performance (∼5% fading after 5000 cycles at high rate of 5 A g−1) can be also obtainable. Our study rendered a simple but effective method to utilize CaC2 as carbon source and may have broad applications such as adsorbents, anode materials for Li/Na-ion batteries.

Rational design of conductive polymer-based supercapacitor (CPSC) by integrating three-dimensional (3D) interconnected electrode materials with porosified electrolyte is of great potential to simultaneously increase the specific capacitance and rate capability of CPSC device. Herein, we describe for the first time a prototype of all-solid-state CPSC using 3D interconnected fibrous polypyrrole (PPy) and 3D porosified electrolyte. The as-made PPy was characterized to possess excellent electron conductivity (∼7.8 S cm−1), 3D interconnected structure, providing fast electron/ion transportation pathway to accelerate the kinetics of interfacial pseudocapacitive reactions. The symmetric PPy-based CPSC device initially delivered a high specific capacity up to 505 mF cm−2 (corresponding to 168 F g−1) at current stream of 2.0 mA cm−2 and was capable of retaining 50% capacitance (∼250 mF cm−2) at high rate (20.0 mA cm−2). Meanwhile, an improved energy density of 44.9 μWh·cm−2 at power of 8 mW cm−2 was achieved. In addition, PPy-CPSC exhibited excellent flexible performance, no obvious degradation of capacitive performance was observed for PPy-CPSC device under bent or twisted.

Stretchable energy storage devices, maintaining the capability of steady operation under large mechanical strain, have become increasing more important with the development of stretchable electronic devices. Stretchable supercapacitors (SSCs), with high power density, modest energy density, and superior mechanical properties are regarded as one of the most promising power supplies to stretchable electronic devices. Conductive polymers, such as polyaniline (PANI), polypyrrole (PPy), polythiophene (PTh) and poly(3,4-ehtylenedioxythiophene) (PEDOT), are among the well-studied electroactive materials for the construction of SSCs because of their high specific theoretical capacity, excellent electrochemical activity, light weight, and high flexibility. Much effort has been devoted to developing stretchable, conductive polymer-based SSCs with different device structures, such as sandwich-type and fiber-shaped type SSCs. This review summarizes the material and structural design for conductive polymer-based SSCs and discusses the challenge and important directions in this emerging field.

Metal-nitrogen-complexed carbon (MNC) materials have received tremendous attention because of their extraordinary catalytic performance and widely spread applications in the fields of electrocatalysis especially oxygen reduction reaction (ORR). Yet currently, an efficient method for the mass production of MNC electrocatalysts under low costs is still lacking. Herein, we explored a facile low-cost route to construct Co-N-decorated carbon (Co-N-C) materials that were capable of providing a considerably higher ORR performance than commercial 20 wt% Pt/C catalyst (comparable activity, higher long-term cycling stability, and tolerance to methanol contamination). The Co-N-C electrocatalysts were mainly facilitated via the efficient dehalogenation of polyvinyl dichloride or polyvinyl chloride and in situ doping with nitrogen and cobalt ions under mild conditions. Besides the rendered promising electrocatalysts for ORR, our developed method may be capable of converting the halogenated polymeric plastic wastes that are massively accumulated in our environment into value-added carbon-based catalytic materials.

Simultaneously improving the loading and accessibility of atomically dispersed metal sites to achieve high-activity and high-throughput electrocatalysis is important yet challenging. Herein, a simple method based on formamide chemistry was developed for the efficient synthesis of 3D flower-like N-doped carbons decorated with highly loaded atomic Fe-N4 motifs. Approximately twice as much atomic Fe (6.84 wt%) was loaded due to the introduction of 2,1,3-benzothiadiazole (Bz) as additional ligands in the preparation of formamide-derived binary ZnFe-NC (f-ZnFe-NC). Meanwhile, with the promotion of Bz, the f-ZnFe-NC precursor also showed improved 3D flower structure that could be robustly inherited into the formation of flower-like Fe-NC product after high-temperature treatment, leading to the obtainment of rich open pores for exposing more atomic Fe sites (site density of 26.6 umol g−1 and turnover of frequency of 1.73 s−1) for oxygen reduction electrocatalysis. Electrochemical measurements showed that the Bz-promoted synthesized Fe-NC (referred to as Bz-Fe1-NC) possessed superior onset potential (1.04 V) and half-wave potential (0.94 V), and its assembled Al-air battery provided a very large specific power of 238.2 mW cm−2 along with high-rate capability and good long-term stability.

Conducting polymer hydrogels emerge as a novel class of polymeric materials that show great potential in many energy, environmental, and biomedical devices. We describe here for the first time a general supramolecular approach toward controlled in situ synthesis of one-dimensional nanostructured conductive hydrogels (polypyrrole (PPy) as a model system) using a rational dopant counterion, which is a disc-shaped liquid crystal molecular copper phthalocyanine-3,4',4″,4‴-tetrasulfonic acid tetrasodium salt (CuPcTs). The dopant molecule CuPcTs cross-linked the PPy chains to form a three-dimensional network that gelated into a hydrogel. The PPy hydrogel could be synthesized in bulk quantities with uniform morphology of self-assembled interconnected nanofibers. The tetra-functional dopant favors a supramolecular self-assembly mechanism to form one-dimensional PPy nanostructures. Furthermore, the enhanced interchain charge transport of CuPcTs doped PPy resulted in greatly enhanced conductivity and pseudocapacitance compared with pristine PPy.

Self-healing materials emerge as a fascinating class of materials important for various technological applications. However, achieving the synergistic characteristics of high conductivity, room-temperature self-healing ability, and decent mechanical properties still remains a critical challenge. Here we develop for the first time a hybrid gel based on self-assembled supramolecular gel and nanostructured polypyrrole that synergizes the dynamic assembly/disassembly nature of metal-ligand supramolecule and the conductive nanostructure of polypyrrole hydrogel and exhibits features of high conductivity (12 S m(-1)), appealing mechanical and electrical self-healing property without any external stimuli, and enhanced mechanical strength and flexibility. The attractive characteristics of the hybrid gel are further demonstrated by a flexible yet self-healable electrical circuit. Our work shows the great potential of self-healing hybrid gel system in flexible electronics and provides a useful strategy to design multifunctional self-healing materials.

Background Osteoarthritis (OA) is a common degenerative joint disease, which seriously impacts the health of elderly. However, there is no effective treatment for curing this disease until now. Numerous studies reported that long noncoding RNAs (lncRNAs) are closely related to the pathogenesis of OA. Therefore, the study aims to investigate the effect of maternally expressed gene 3 (MEG3) on lipopolysaccharide (LPS)-induced inflammatory injury of ATDC5 cells. Methods Different concentrations (0, 1, 5, and 10 μg/ml) of LPS were used to induce ATDC5 cells injury. The specific expressing vectors were then transfected into ATDC5 cells to alter MEG3, Sirt1 and miR-203 expressions. Flow cytometry, luciferase reporter, qRT-PCR and western blot assays were used to detect cell viability, apoptosis, and the expressions of apoptosis-related proteins and pro-inflammatory factors (IL-1β, IL-6, IL-8 and TNF-α). Meanwhile, ELISA was used for analyzing the concentrations of inflammatory cytokines in culture supernatant. Besides, the key pathways of PI3K/AKT and NF-κB were examined by western blot. Results LPS decreased cell viability, increased cell apoptosis, promoted the release of pro-inflammatory factors, and down-regulated MEG3 expression, Moreover, MEG3 knockdown alleviated LPS-induced inflammatory injury. MEG3 acted as a competing endogenous RNAs (ceRNA) for miR-203, and MEG3 knockdown reduced inflammatory injury by regulating miR-203. Furthermore, miR-203 positively regulated Sirt1 expression, and Sirt1 alleviated LPS-induced inflammatory injury via mediating PI3K/AKT and NF-κB pathways. Conclusion This study showed that MEG3 knockdown alleviated LPS-induced inflammatory injury in ATDC5 cells by regulating miR-203 expression. Hence, the findings may offer a potential treatment perspective of OA.

Electrochemically active conducting polymers are an important class of materials for applications in energy storage devices such as batteries and supercapacitors, owing to their advantageous features of unique three-dimensional (3D) porous microstructure, high capacitive energy density, scalable synthesis and light weight. Here, we synthesized a nanostructured conductive polypyrrole (PPy) hydrogel via an interfacial polymerization method. The simple synthesis chemistry offers the conductive hydrogel tunable nanostructures and electrochemical performance, as well as scalable processability. Moreover, the unique 3D porous nanostructure constructed by interconnected polymer nanospheres endows PPy hydrogels with good mechanical properties and high performance acting as supercapacitor electrodes with a specific capacitance of ∼380 F g−1, excellent rate capability, and areal capacitance as high as ∼6.4 F cm−2 at a mass loading of 20 mg cm−2.

The effect of the surface modification with a silane coupling agent (octyl-trimethoxysilane) of aluminum (Al) nanoparticles on the dielectric breakdown behaviors of polyethylene (PE)/Al nanocomposites was investigated in comparison of the influence of the improvement of the interfacial adhesion between Al nanoparticles and PE using a compatibilizer (maleic anhydride grafted polyethylene). It was found that when compared with the other modification approaches, the surface-treated Al nanofiller with the silane coupling agent makes it possible for the PE/Al nanocomposites to still keep the relatively higher breakdown strength even in the higher Al loading level above 14 vol %, which can be understood in terms of the better interfacial adhesion between the surface-treated particle dispersion and the matrix. The combined effects of the Al nanoparticles on the different factors which influence the dielectric breakdown processes in polymer matrix such as microstructure, conductivity, and crystallinity of the nanocomposites were discussed in detail. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

The development of a scalable, low-cost, and versatile biosensor platform for the sensitive and rapid detection of human metabolites is of great interest for healthcare, pharmaceuticals, and medical science. On the basis of hierarchically nanostructured conducting polymer hydrogels, we designed a flexible biosensor platform that can detect various human metabolites, such as uric acid, cholesterol, and triglycerides. Owing to the unique features of conducting polymer hydrogels, such as high permeability to biosubstrates and rapid electron transfer, our biosensors demonstrate excellent sensing performance with a wide linear range (uric acid, 0.07–1 mM; cholesterol, 0.3–9 mM, and triglycerides, 0.2–5 mM), high sensitivity, low sensing limit, and rapid response time (∼3 s). Given the facile and scalable processability of hydrogels, the proposed conductive hydrogels-based biosensor platform shows great promise as a low-cost sensor kit for healthcare monitoring, clinical diagnostics, and biomedical devices.

Pressure sensing is an important function of electronic skin devices. The development of pressure sensors that can mimic and surpass the subtle pressure sensing properties of natural skin requires the rational design of materials and devices. Here we present an ultra-sensitive resistive pressure sensor based on an elastic, microstructured conducting polymer thin film. The elastic microstructured film is prepared from a polypyrrole hydrogel using a multiphase reaction that produced a hollow-sphere microstructure that endows polypyrrole with structure-derived elasticity and a low effective elastic modulus. The contact area between the microstructured thin film and the electrodes increases with the application of pressure, enabling the device to detect low pressures with ultra-high sensitivity. Our pressure sensor based on an elastic microstructured thin film enables the detection of pressures of less than 1Pa and exhibits a short response time, good reproducibility, excellent cycling stability and temperature-stable sensing.

Glucose enzyme biosensors have been shown useful for a range of applications from medical diagnosis, bioprocess monitoring, to beverage industry and environmental monitoring. We present here a highly sensitive glucose enzyme sensor based on Pt nanoparticles (PtNPs)-polyaniline (PAni) hydrogel heterostructures. High-density PtNPs were homogeneously loaded onto the three-dimensional (3D) nanostructured matrix of the PAni hydrogel. The PtNP/PAni hydrogel heterostructure-based glucose sensor synergizes the advantages of both the conducting hydrogel and the nanoparticle catalyst. The porous structure of the PAni hydrogel favored the high density immobilization of the enzyme and the penetration of water-soluble molecules, which helped efficiently catalyze the oxidation of glucose. In addition, the PtNPs catalyzed the decomposition of hydrogen peroxide that was generated during the enzymatic reaction. The transferred charges from these electrochemical processes were efficiently collected by the highly conducting PtNP/PAni hydrogel heterostructures. The glucose enzyme sensor based on this heterostructure exhibited unprecedented sensitivity, as high as 96.1 μA·mM(-1)·cm(-2), with a response time as fast as 3 s, a linear range of 0.01 to 8 mM, and a low detection limit of 0.7 μM.

Space charge behavior of the composite of polyethylene and nano-MgO was investigated with pulsed electroacoustic method (PEA). It is found that space charge was well suppressed as the content of nano-MgO is less than 2.0%wt. Also it could be seen that bi-polar injection occurs in the composite as electrical stress increases to 60 kV/mm. Comparing to the amount of space charge in the short-circuited pure cross-linking polyethylene, it is very low in the composite. It is more interesting that semiconductive electrode has a great effect on space charge in both cross-linking polyethylene and the composite. In order to know space charge injection threshold, dc conduction was measured at various electrical stresses. And it is found that nano-MgO increases the threshold.

Nano-SiO2/ low density polyethylene composite and micro-SiO2/ LDPE composite were prepared via a method of double-solution mixture. The discharging current of all samples after being prestressed at a DC electric field were recorded via Keithley 6517A. Currents of the both composites are less than those of pure LDPE. In addition, the curve shape of the nanocomposite is different from that of pure LDPE and or the microcomposite, which suggests the slow polarization mechanism of the nanocomposite containing nano-SiOx differs from that of pure LDPE and or the microcomposite. The slow polarization characteristics of all samples were analyzed via a method of Fast Fourier Transfer (FFT) in a frequency domain and parameters of epsiv' - epsivinfin and epsiv" of all samples were obtained by converting the discharging currents. The polarization intensity of pure LDPE is the highest among all of the samples, while the polarization peak locates at lowest frequency. At the same time, the polarization intensity of microcomposite was higher than that of nanocomposite, and the polarization peak location of microcomposite was lower frequency than that of nanocomposite. The polarization peak of the nanocomposite increases with the loading level whereas that of the microcomposite does not vary with loading level at all.