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Redox-active organic molecules have drawn extensive interests in redox flow batteries (RFBs) as promising active materials, but employing them in nonaqueous systems is far limited in terms of useable capacity and cycling stability. Here we introduce azobenzene-based organic compounds as new active materials to realize high-performance nonaqueous RFBs with long cycling life and high capacity. It is capable to achieve a stable long cycling with a low capacity decay of 0.014% per cycle and 0.16% per day over 1000 cycles. The stable cycling under a high concentration of 1 M is also realized, delivering a high reversible capacity of ~46 Ah L −1 . The unique lithium-coupled redox chemistry accompanied with a voltage increase is observed and revealed by experimental characterization and theoretical simulation. With the reversible redox activity of azo group in π-conjugated structures, azobenzene-based molecules represent a class of promising redox-active organics for potential grid-scale energy storage systems. Organic molecules are promising active materials for nonaqueous redox-flow batteries (RFBs), but suffer from poor cycling stability. Here, the authors introduce azobenzene-based molecules as new type of highly soluble and stable active materials to realize high-capacity and long-life nonaqueous RFBs.

In this study, Cu@Ag core–shell nanoparticles (NPs) with highly environmental stability were synthesized successfully by combining the NaBH 4 reduction method with the transmetallation reaction, and the Cu@Ag nano-ink was prepared for direct writing flexible electronics. The structure, component, thermal stability and oxidation resistance of Cu NPs and Cu@Ag core–shell nanoparticles were characterized and discussed systematically. The results showed that Cu NPs could be obtained via the reduction of Cu 2+ ions by using cetyltrimethylammonium bromide (CTAB) as a dispersing agent under an excess of sodium hydroxide (NaOH) and sodium borohydride (NaBH 4 ) in aqueous solution. And the Cu@Ag core–shell nanoparticles with uniform Ag shell and Cu core can be fabricated with the transmetallation reaction that Ag + ions were reduced by the copper atoms on the surface of Cu NPs at pH 7, and the Cu core were kept from oxidation from the Ag shell. Besides, Cu@Ag nano ink were fabricated by dispersing Cu@Ag core–shell nanoparticles in ethylene glycol, and Cu@Ag conductive pattern were directly drawn on ordinary photo paper using a roller pen filled with 30 wt% Cu@Ag nano ink. The electrical resistivity of the conductive Cu@Ag pattern obtained from the nano ink was as low as 13.8 μΩ cm −1 due to the continuous interconnections between the nanoparticles established when thermal sintered at 150 °C for 1 h under N 2 . When the conductive wires of a lamp were connected to the two ends of the written conductive line, the lamp was illuminated immediately. It demonstrated that the complicated Cu@Ag nano-ink pattern had very good conductivity and applicability. This work provides an effective approach to prepare Cu@Ag core–shell nano-ink for direct writing flexible electronics.

Silver nanowires (AgNWs) were chemically etched to significantly increase the surface roughness and then self-assembled on the liquid/gas interfaces via the interfacial assembly method to obtain aligned chemically etched silver nanowire films. The as-fabricated silver nanowire films were used as novel surface-enhanced Raman scattering (SERS) substrates. The morphologies and plasmon characteristics of the substrates were investigated using multiple measurement methods. The performance of as-fabricated substrates was measured using rhodamine B as a probe. The detection limitation can be as low as 10 −11  M. The greatly improved plasmonic properties are attributed to the efficient light coupling and larger electromagnetic field enhancement. The novel set of SERS substrates of aligned chemically etched AgNWs is believed to be important for efficient, homogeneous, and ultrasensitive SERS sensing applications.

The four-arm star copolymers poly(methacrylic acid)-poly(2-hydroxyethyl methacrylate-disulfide~)-poly(poly(ethylene glycol) methyl ether methacrylate) (4AS-PMAA x -(PHEMA-SS~) y -PPEGMA z ) with four different block ratios were synthesized and could self-assembled into cross-linked polymer micelles for the exploration of the structure-property relationship. The cross-linked polymer micelles in aqueous solution had low critical micelle concentration (CMC) values (1.9-4.6 mg/L), which exhibited better stability than non-cross-linked micelles. The CMC value decreased with the increase of the length of inner PMAA core and hydrophobic PHEMA cross-linked middle layer. The blank and doxorubicin (DOX)-loaded micelles with different block ratios were prepared by dialysis with the particle sizes of 120-240 nm. The longer inner PMAA core and cross-linked middle layer enhanced the drug loading content (DLC) results and led to relatively bigger particle sizes of polymer micelles. The in vitro DOX release data revealed that DOX-loaded micelles had low DOX cumulative release percentages of 18-37% after 110 h at pH 7.4, but up to 83-90% when introducing reductant GSH at pH 5.0. The 4AS-PMAA 21.2 -(PHEMASS≈) 13.1 -PPEGMA 5.1 micelles with the longest PMAA core had the largest cumulative release of 90.1%. The DOX release process and mechanism of the micelles at different conditions fitted well with the semi-empirical equation. Overall, the results demonstrated that the block ratios and pH/redox-responsiveness of these four-arm star copolymers could be well-controlled and their self-assembled cross-linked micelles as anticancer drug carrier system could be improved by optimizing the different ratios.

Ordered nanopatterns of triblock copolymer polystyrene- block -poly(2-vinylpyridine)- block - poly (ethylene oxide)(PS- b -P2VP- b -PEO) have been achieved by the addition of lithium chloride (LiCl). The morphological and structural evolution of PS- b -P2VP- b -PEO/LiCl thin films were systematically investigated by varying different experimental parameters, including the treatment for polymer solution after the addition of LiCl, the time scale of ultrasonic treatment and the molar ratio of Li + ions to the total number of oxygen atoms (O) in PEO block and the nitrogen atoms (N) in P2VP block. When toluene was used as the solvent for LiCl, ordered nanopattern with cylinders or nanostripes could be obtained after spin-coating. The mechanism of nanopattern transformation was related to the loading of LiCl in different microdomains.

A novel gap-plasmon of Fe3O4@Ag core-shell nanoparticles for surface enhanced fluorescence detection of Rhodamine B（RB） was developed. Fe3O4@Ag core-shell nanostructures with Ag shell and Fe3O4 core were synthetized by self-assembled method with the assistance of 3-mercaptopropyl trimethoxy silane（MPTS）. To study the RB fluorescence enhanced by gap-plasmon, the fluorescence properties of RB on the substrates with different nanogap densities were systematically investigated, and the results showed that the fluorescence intensity of RB on Fe3O4@Ag core-shell NPs substrate was much stronger than that on bare glass substrate, and the fluorescence intensity was further improved by using multilayer Fe3O4@Ag core-shell NPs substrate which had higher nanogap density. Different from the mechanism that is based on the maximum overlap of the surface plasmon resonance（SPR） band and emission band, the mechanism of the fluorescence enhancement in our work is based on the localized surface plasmon（LSP） and the gap plasmon near-field coupling with the Fe3O4@Ag core-shell NPs. Besides, the detection limit obtained was as low as 1×10~（-7） mol/L, and the Fe3O4@Ag core-shell NPs substrate had high selectivity for RB fluorophores. It was demonstrated that the Fe3O4@Ag core-shell NPs substrate had activity, good stability, and selectivity for fluorescence detection of RB. And the detection of RB by the surface plasmon enhanced fluorescence was more convenient and rapid than the traditional detection methods in previous works.

The widespread implementation of supercapacitors is hindered by the limited energy density and the pricey porous carbon electrode materials. The cost of porous carbon is a significant factor in the overall cost of supercapacitors, therefore a high carbon yield could effectively mitigate the production cost of porous carbon. This study proposes a method to produce porous carbon spheres through a spray drying technique combined with a carbonization process, utilizing renewable enzymatic hydrolysis lignin as the carbon source and KOH as the activation agent. The purpose of this study is to examine the relationship between the quantity of activation agent and the development of morphology, pore structure, and specific surface area of the obtained porous carbon materials. We demonstrate that this approach significantly enhances the carbon yield of porous carbon, achieving a yield of 22% in contrast to the conventional carbonization-activation method (9%). The samples acquired through this method were found to contain a substantial amount of mesopores, with an average pore size of 1.59 to 1.85 nm and a mesopore ratio of 25.6%. Additionally, these samples showed high specific surface areas, ranging from 1051 to 1831 m 2·g −1. Zinc ion hybrid capacitors with lignin-derived porous carbon cathode exhibited a high capacitance of 279 F·g −1 at 0.1 A·g −1 and an energy density of 99.1 Wh·kg −1 when the power density was 80 kW·kg −1. This research presents a novel approach for producing porous carbons with high yield through the utilization of a spray drying approach.

Understanding the structural formation mechanism of hard carbon and the relationship between its microstructure and sodium‐ion storage performance is critical for the precise fabrication of hard carbon. Herein, lignin‐derived hard carbons with tunable microstructures were prepared via one‐step carbonization by tuning carbonization temperatures (600°C−1600°C) and time (0−6 h). The graphitic microcrystalline structures in hard carbons become more ordered with increasing carbonization temperature and time, which in turn leads to the reduced interlayer spacing of graphene layers, decreased defect concentration, and increased size and volume of the closed pores. The pseudo‐graphitic structures with expanded interlayer spacing and abundant defect structures contribute to enhanced slope‐potential capacity, whereas the sodium‐ion accessible closed pores with large pore volume contribute to improved plateau‐potential capacity. A small closed‐pore size is beneficial for enhancing the rate performance. The hard carbons displayed an adsorption/intercalation‐dominated to a pore‐filling‐dominated mechanism with increasing carbonization temperature and time. The optimized hard carbon exhibited a high reversible capacity (322 mAh g −1 at 0.05 A g −1 ) with a plateau‐potential capacity of 246 mAh g −1 , and good rate performance. These findings provide fundamental insights for the structural revolution and sodium‐ion storage mechanism of hard carbon anodes, which could pave the way for understanding how the structure evolves and how we precisely design high‐performance hard carbon anodes.

Poly( N -isopropylacrylamide- co -N-vinylpyrrolidone) [P(NIPAM- co -NVP)] copolymers with different content of N -vinylpyrrolidone (NVP) were synthesized, and reversible aggregation kinetics of the copolymers in aqueous solutions was investigated with elastic light scattering (ELS) spectra. The results indicated that the apparent activation energy of aggregation process during heating and dissociation process during cooling increased with the NVP content increasing. The phase transition temperature also increased as the content of NVP increased, suggesting that the hydrophilic nature of NVP strongly affected the phase behavior of the copolymer solutions. The higher the content of NVP, the higher the temperature required to break the balance between the hydrophilic and hydrophobic interaction. Besides, during heating and cooling process, the phase transition hysteresis of P(NIPAM- co -NVP) chains decreased when the hydrophilic comonomer increased.

A series of nanostructured zinc compounds with different nanostructures such as nanobelts, flake-like, flower-like, and twinning crystals was synthesized using zinc acetate (Zn(Ac) 2 ) as a single-source. The evolution of the zinc compounds from layered basic zinc acetate (LBZA) to bilayered basic zinc acetate (BLBZA) and twinned ZnO nano/microcrystal was studied. The low-angle X-ray diffraction spectra indicate the layered spacing is 1.34 and 2.1 nm for LBZA and BLBZA, respectively. The Fourier transform infrared (FTIR) spectra results confirmed that the bonding force of acetate anion with zinc cations decreases with the phase transformation from Zn(Ac) 2 to BLBZA, and finally to LBZA. The OH − groups gradually replaced the acetate groups coordinated to the matrix zinc cation, and the acetate groups were released completely. Finally, the Zn(OH) 2 and ZnO were formed at high temperature. The conversion process from Zn(Ac) 2 to ZnO with release of acetate anions can be described as Zn(Ac) 2  → BLBZA → LBZA → Zn(OH) 2  → ZnO.