Nanocomposites of chitosan and graphene oxide are prepared by simple self-assembly of both components in aqueous media. It is observed that graphene oxide is dispersed on a molecular scale in the chitosan matrix and some interactions occur between chitosan matrix and graphene oxide sheets. These are responsible for efficient load transfer between the nanofiller graphene and chitosan matrix. Compared with the pure chitosan, the tensile strength, and Young's modulus of the graphene-based materials are significantly improved by about 122 and 64%, respectively, with incorporation of 1 wt % graphene oxide. At the same time, the elongation at the break point increases remarkably. The experimental results indicate that graphene oxide sheets prefer to disperse well within the nanocomposites.

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Future generations of wearable electronic systems and mobile communication place a great demand for harvesting energy from ambient environments or human movements. Soft fiber-based electric power generators are attractive in meeting the requirements of wearable devices because of efficient energy conversion performance, high durability and comfort. In this paper, we present a novel all-fiber wearable electric power nanogenerator, which consists of a PVDF-NaNbO 3 nanofiber nonwoven fabric as an active piezoelectric component, and an elastic conducting knitted fabric, made from segmented polyurethane and silver coated polyamide multifilament yarns, as the top and bottom electrodes. The non-uniform deformation distribution in a compressed nanogenerator device determines the complex operating modes in the piezoelectric nanofiber nonwoven fabric. The nanogenerator consistently produces a peak open-circuit voltage of 3.4 V and a peak current of 4.4 mA in cyclic compression tests at 1 Hz and a maximum pressure of 0.2 MPa, which is comparable to normal human walking motion.More importantly, the all-fiber nanogenerator retains its performance after 1 000 000 compression cycles, demonstrating great promise as a wearable energy harvester that converts the mechanical energy of human movement into electricity. Broader contextFuture generations of wearable electronic systems place a great demand for harvesting energy from the ambient environment or human movement rather than relying on a rechargeable battery power supply. Flexible and so ber-based electric power generators can be designed in such a manner that low levels of strain and thus high fatigue resistance can be achieved over a large number of deformation cycles. In this work, we demonstrate the rst integration of a PVDF-NaNbO 3 nanober nonwoven fabric and elastic conducting knitted fabric for simultaneously harvesting mechanical energy. More importantly, the all-ber nanogenerator retains its performance aer one million compression cycles, which is the highest reported number for this kind of generator. The robust so ber-based electric power generator is attractive because of its efficient energy conversion performance, high durability and comfort to wearers. This new type of all-ber nanogenerator demonstrates great promise as a wearable energy harvester that converts the mechanical energy of human movement into electricity.