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Abstract: Polymer‐based composites are of high interest in the field of thermoelectric (TE) materials because of their properties: abundance, low thermal conductivity, and nontoxicity. In applications, like TE for wearable energy harvesting, where low operating temperatures are required, polymer composites demonstrate compatible with the targeted specifications. The main challenge is reaching high TE efficiency. Fillers and chemical treatments can be used to enhance TE performance of the polymer matrix. The combined application of vertically aligned carbon nanotubes forest (VA‐CNTF) is demonstrated as fillers and chemical post‐treatment to obtain high‐efficiency TE composites, by dispersing VA‐CNTF into a poly (3,4‐ethylenedioxythiophene) polystyrene sulfonate matrix. The VA‐CNTF keeps the functional properties even in flexible substrates. The morphology, structure, composition, and functional features of the composites are thoroughly investigated. A dramatic increase of power factor is observed at the lowest operating temperature difference ever reported. The highest Seebeck coefficient and electrical conductivity are 58.7 µV K−1 and 1131 S cm−1, respectively. The highest power factor after treatment is twice as high in untreated samples. The results demonstrate the potential for the combined application of VA‐CNTF and chemical post‐treatment, in boosting the TE properties of composite polymers toward the development of high efficiency, low‐temperature, flexible TEs. [ABSTRACT FROM AUTHOR]

Carbon nanofibrous (CNF) films are of great interest for various applications, e.g., as substrates for electrodes, sensors, or catalysts. Here, a fast microwave-assisted synthesis is reported to fabricate square-centimeter large free-standing carbon nanofibrous films of approximately 10 μm thickness utilizing nickel-based catalysts and ethanol as carbon source. The obtained CNF coatings exhibit a good stability and partial self-delamination from the substrate is observed, which enables their easy detachment from the substrate without the need for further treatment. Scanning electron microscopy is applied to investigate the morphology of the films and to develop a growth model. [ABSTRACT FROM AUTHOR]