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Piezoelectric energy harvesters (PEHs) have attracted considerable attention in fields such as energy harvesting and motion monitoring due to their high electromechanical conversion capabilities. Conventionally, PEHs are obtained by dispersing piezoelectric nanofillers in a polymer matrix to achieve piezoelectric output and flexibility. However, the limited internal stress transmission results in a low piezoelectric performance, failing to meet application demands. Herein, a three-dimensional (3D) barium titanate (BT) ceramic framework is successfully prepared by pine wood-assisted sol–gel synthesis, and then composited with polydimethylsiloxane (PDMS) to form elastomer PEHs. In order to solve the low mass loading of BT due to the limited solubility of the precursors in the sol–gel, the presynthesized BT nanoparticles (NPs) are introduced into the sol–gel solution. The interconnected 3D PDMS/BT networks are found to facilitate the transmission of load along the BT framework and thereby give a large piezoelectric response. The PEH with 75% BT NPs achieves the optimal electromechanical conversion performance, with an open-circuit voltage (VOC) of 86.6 V, a short-circuit current (ISC) of 17.3 μA, and the maximum output power density of 39.98 μW cm−2 with loading an external resistance of 10 MΩ. This work provides a new approach to develop 3D piezoelectric elastomer networks with a high output performance and extends applications for self-powered devices. [ABSTRACT FROM AUTHOR]

Piezoelectric nanogenerators (PENGs) are booming for energy collection and wearable energy supply as one of the next generations of green energy-harvesting devices. Balancing the output, safety, degradation, and cost is the key to solving the bottleneck of PENG application. In this regard, yttrium (Y)-doped zinc oxide (ZnO) (Y-ZnO) was synthesized and embedded into polylactide (PLLA) for developing degradable piezoelectric composite films with an enhanced energy-harvesting performance. The synthesized Y-ZnO exhibits high piezoelectric properties benefiting from the stronger polarity of the Y-O bond and regulation of oxygen vacancy concentration, which improve the output performance of the composite film with Y-ZnO and PLLA (Y-Z-PLLA). The obtained open-circuit voltage ( V oc ), short-circuit current ( I sc ), and instantaneous power density of the optimized Y-Z-PLLA PENG reach 17.52 V, 2.45 μA, and 1.76 μW/cm 2 , respectively. The proposed PENG also shows good degradability. In addition, practical applications of the proposed PENG were demonstrated by converting biomechanical energy, such as walking, running, and jumping, into electricity.