Flexible, wearable, and portable energy storage devices with high-energy density are crucial for next-generation electronics. However, the current battery technologies such as lithium ion batteries have limited theoretical energy density. Additionally, battery materials with small scale and high flexibility which could endure the large surface stress are highly required. In this study, a yarn-based 1D Zn-air battery is designed, which employs atomic layer thin Co O nanosheets as the oxygen reduction reaction/oxygen evolution reaction catalyst. The ultrathin nanosheets are synthesized by a high-yield and facile chemical method and show a thickness of only 1.6 nm, corresponding to few atomic layers. The 1D Zn-air battery shows high cycling stability and high rate capability. The battery is successfully knitted into clothes and it shows high stability during the large deformation and knotting conditions.

Air permeability is crucial to nanofibrous membrane applications, such as in wound dressing and membrane distillation. Herein, hierarchical structure membrane is prepared layer by layer with different fiber diameters, using electrospinning method. The results showed that with different layer arrangement results in different air permeability, and optimal condition is found.

Aerogel fiber, with the characteristics of ultra-low density, ultra-high porosity, and high specific surface area, is the most potential candidate for manufacturing wearable thermal insulation material. However, aerogel fibers generally show weak mechanical properties and complex preparation processes. Herein, through firstly preparing a cellulose acetate/polyacrylic acid (CA/PAA) hollow fiber using coaxial wet-spinning followed by injecting the silk fibroin (SF) solution into the hollow fiber, the CA/PAA-wrapped SF aerogel fibers toward textile thermal insulation were successfully constructed after freeze-drying. The sheath (CA/PAA hollow fiber) possesses a multiscale porous structure, including micropores (11.37 ± 4.01 μm), sub-micron pores (217.47 ± 46.16 nm), as well as nanopores on the inner (44.00 ± 21.65 nm) and outer (36.43 ± 17.55 nm) surfaces, which is crucial to the formation of a SF aerogel core. Furthermore, the porous CA/PAA-wrapped SF aerogel fibers have many advantages, such as low density (0.21 g/cm3), high porosity (86%), high strength at break (2.6 ± 0.4 MPa), as well as potential continuous and large-scale production. The delicate structure of multiscale porous sheath and ultra-low-density SF aerogel core synergistically inhibit air circulation and limit convective heat transfer. Meanwhile, the high porosity of aerogel fibers weakens heat transfer and the SF aerogel cellular walls prevent infrared radiation. The results show that the mat composed of these aerogel fibers exhibits excellent thermal insulating properties with a wide working temperature from −20 to 100 °C. Therefore, this SF-based aerogel fiber can be considered as a practical option for high performance thermal insulation.

Electrical voltage has a crucial effect on the nanofiber morphology as well as the jet number in the electrospinning process, while few literatures were found to explain the deep mechanism. Herein, the electrical field distribution around the spinning electrode was studied by the numerical simulation firstly. The results show that the electrical field concentrates on the tip of a protruding droplet under relatively low voltage, while subsequently turns to the edge of needle tip when the protruding droplet disappears under high voltage. The experimental results are well consistent with the numerically simulated results, that is, only one jet forms at low voltage (below 20 kV for PVDF-HFP and PVA nanofiber), but more than one jet forms under high voltage (two jets for PVDF-HFP nanofiber, four jets for PVA nanofiber). These more jets lead to (1) higher fiber diameter resulting from actually weaker electrical field for each jet and (2) wide distribution of fiber diameters due to unstable spinning process (changeable jet number/site/height) under high voltage. The results will benefit the nanofiber preparation and application in traditional single-needle electrospinning and other electrospinning methods.

Purpose The evaluation of the electron transfer capacities (ETC) of DOM is important to understand their roles in microbial activity, pollution degradation, and metal mobility. Those currently used methods to quantify ETC, such as Zn and Fe 3+ assays, are normally time consuming and usually require experience and skills to achieve reproducible results. The aim of this paper is to develop a rapid and simple approach to accurately and directly quantify the ETC of DOM. Materials and methods DOM was extracted from sewage sludge compost. Cycle voltammetry (CV) was used to investigate the redox behavior of DOM derived from sludge compost. Chronoamperometry (CA) was employed to study the electron-accepting capacities (EAC) and electrondonating capacities (EDC) by applying fixed positive or negative potentials to a working electrode in a conventional three-electrode cell. For comparison, the EAC and EDC of DOM were also determined by chemical methods using Zn as the reductant and Fe 3+ as the oxidant. The reversible electron transfer of DOM was studied electrochemically by CA with a multi-potential step technique. Results and discussionThe CV of sludge DOM displayed that a couple of quasi-reversible redox peaks with a formal potential of -0.866 V (vs. Ag/AgCl), demonstrating that the DOM was capable of reversibly transferring electrons. The value of EAC was determined by CA to be 361.6 μmol e− (g C) −1 at a potential of −0.6 V (vs. Ag/AgCl), and the value of initial EDC was 5.0 μmol e− (g C) −1 at a potential of +0.4 V (vs. Ag/AgCl). Both the values of EAC and EDC depended on the applied potentials on the working electrode. The results determined by the proposed method were comparable with those by using chemical methods. Conclusions A rapid electrochemical approach was employed to investigate the EAC and EDC of DOM extracted from sewage sludge compost. The acquired values of EAC and EDC were comparable with those measured by chemical methods using zinc as the reductant and ferric iron as the oxidant. The determination could be completed in tens of seconds, which was faster and more direct than conventional chemical methods.