Microstructure and Thermoelectric Characterization of Composite Nanofiber Webs Derived from Polyacrylonitrile and Sodium Cobalt Oxide Precursors

Preparation and characterization of conjugated PVA/PANi blend films doped with functionalized graphene for thermoelectric applications

Flexible nanocomposite thick films consisting of PVA0.7PANi0.3 polymer blend doped with different concentrations of nanoplatelets functionalized Graphene (NPFGx) (where x = 0, 5, 10, 15, 20, and 25 wt.%) were fabricated using the solution cast technique. Scanning electron microscopy (SEM), X-ray diffractometer (XRD), energy dispersive spectroscopy analysis (EDX), and Fourier-transform infrared spectra (FT-IR) were used to study the structure of the samples. The results showed that the ordered structure, its orientation, the PANis' well dispersion, and the electrostatic forces play a significant role in enhancing the interfaces between the polymer blend and the NPFG. Thermogravimetric analyses (TGA) and Thermoelectrical analyses (TE) showed that the PVA-PANi conducts a promised conjugated blend for thermoelectric applications. The introduction of the NPFG contents into the blend increased the TE measurements as the DC electrical conductivity ≈ 0.0114 (S cm-1), power factor ≈ 3.93 × 10-3 (W m-1 K-2), and Z.T. ≈ 8.4 × 10-7, for the 25 wt.% NPFG nanocomposite film. The effect of the polymers' phonon contribution in the thermal conductivity controlling and enhancing the thermal stability of the prepared nanocomposite films.

Biomimetic Exogenous "Tissue Batteries" as Artificial Power Sources for Implantable Bioelectronic Devices Manufacturing

Implantable bioelectronic devices (IBDs) have gained attention for their capacity to conformably detect physiological and pathological signals and further provide internal therapy. However, traditional power sources integrated into these IBDs possess intricate limitations such as bulkiness, rigidity, and biotoxicity. Recently, artificial "tissue batteries" (ATBs) have diffusely developed as artificial power sources for IBDs manufacturing, enabling comprehensive biological-activity monitoring, diagnosis, and therapy. ATBs are on-demand and designed to accommodate the soft and confining curved placement space of organisms, minimizing interface discrepancies, and providing ample power for clinical applications. This review presents the near-term advancements in ATBs, with a focus on their miniaturization, flexibility, biodegradability, and power density. Furthermore, it delves into material-screening, structural-design, and energy density across three distinct categories of TBs, distinguished by power supply strategies. These types encompass innovative energy storage devices (chemical batteries and supercapacitors), power conversion devices that harness power from human-body (biofuel cells, thermoelectric nanogenerators, bio-potential devices, piezoelectric harvesters, and triboelectric devices), and energy transfer devices that receive and utilize external energy (radiofrequency-ultrasound energy harvesters, ultrasound-induced energy harvesters, and photovoltaic devices). Ultimately, future challenges and prospects emphasize ATBs with the indispensability of bio-safety, flexibility, and high-volume energy density as crucial components in long-term implantable bioelectronic devices.

Regulating Na Occupation to Introduce Non-Fermi-Liquid States of NaxCoO2 for Enhanced Water Oxidation Activity

The couplings among fundamental quantum parameters provide versatile freedom of manipulations for useful electronic structures, based on which optimized oxygen evolution reaction (OER) performances can be achieved. In this work, we demonstrate the successful regulation of the electronic structure in layered Na_xCoO₂ oxides to introduce a non-Fermi-liquid (NFL) state by adjusting the Na content and Na occupation in the lattice. The presence of an NFL is facilitated by the weakened electron-electron correlation when the on-site Coulomb repulsion of Co⁴⁺ with Na⁺ and oxygen vacancy with Na⁺ is balanced. As a feature of NFL, the metallic states in the vicinity of the Fermi energy contribute to a fast electron transfer efficiency and eventually to an improved OER performance. These findings open up a new avenue to design highly efficient OER electrocatalysts in strong electron-correlated transition metal material systems by consideration of couplings among the fundamental quantum parameters.

Thermo-active Smart Electrospun Nanofibers

The recent burst of research on smart materials is a clear evidence of the growing interest of the scientific community, industry, and society in the field. The exploitation of the great potential of stimuli-responsive materials for sensing, actuation, logic, and control applications is favored and supported by new manufacturing technologies, such as electrospinning, that allows to endow smart materials with micro- and nano-structuration, thus opening up additional and unprecedented prospects. In this wide and lively scenario, this article systematically reviews the current advances in the development of thermo-active electrospun fibers and textiles, sorting them, according to their response to the thermal stimulus. Hence, several platforms including thermo-responsive systems, shape memory polymers, thermo-optically responsive systems, phase change materials, thermoelectric materials, and pyroelectric materials, have been described and critically discussed. The difference in active species and outputs of the aforementioned categories has been highlighted, evidencing the transversal nature of temperature stimulus. Moreover, the potential of novel thermo-active materials has been pointed out, revealing how their development could take to utmost interesting achievements. This article is protected by copyright. All rights reserved.

New Progress on Fiber-Based Thermoelectric Materials: Performance, Device Structures and Applications

With the rapid development of wearable electronics, looking for flexible and wearable generators as their self-power systems has proved an extensive task. Fiber-based thermoelectric generators (FTEGs) are promising candidates for these self-powered systems that collect energy from the surrounding environment or human body to sustain wearable electronics. In this work, we overview performances and device structures of state-of-the-art fiber-based thermoelectric materials, including inorganic fibers (e.g., carbon fibers, oxide fibers, and semiconductor fibers), organic fibers, and hybrid fibers. Moreover, potential applications for related thermoelectric devices are discussed, and future developments in fiber-based thermoelectric materials are also briefly expected.