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Graphical abstract Highlights • Low-temperature sintering properties and mechanism of BCTZY NFs were clarified. • BCTZY NFs displayed a high T C owing to its discontinuous physical property. • Vertical alignment and donor doping of Y3+ greatly enhanced electrical properties. • BCTZY NF-based NGs showed great potential in tiny energy harvesting application. Abstract Flexible lead-free (Ba 0.85 Ca 0.15)(Ti 0.9 Zr 0.1)O 3 -0.2 mol%Y nanofibers (BCTZY NFs) were synthesized by electrospinning and their corresponding nanogenerators (NGs) with vertical alignments were fabricated. The low-temperature sintering properties of BCTZY NFs were investigated, to optimize their synthesis path and minimize the thermal energy consumption during the sintering process. The continuity, flexibility, and stability of the BCTZ-based NFs were improved by adding Y3+. Moreover, the temperature-evolved Raman spectra displayed a high Curie temperature of 280 °C for BCTZY NFs, which was far higher than that of about 90 °C for BCTZ-based ceramic bulks, owing to the discontinuous physical property of NFs. The dielectric, ferroelectric, and piezoelectric properties of the vertically aligned BCTZY NFs/PDMS were estimated and compared with those of BCTZ NFs/PDMS composites, to verify the advantages of vertical alignments and the donor doping effect of Y3+. Vertically aligned BCTZY NF-based NGs showed an average V OC of 3.0 V and I SC of 85 nA by finger tapping, suggesting their potential applications in tiny energy harvesting. [ABSTRACT FROM AUTHOR]

BCZT-CuY/rGO/PDMS composites with excellent elasticity and flexibility, and their nanogenerators (NGs) with favorable electrical properties, were fabricated. The impact of rGO on the dispersion of BCZT-CuY, the mechanical properties of BCZT-CuY/rGO/PDMS, and electrical performance of BCZT-CuY/rGO-based NGs were systematically investigated. The results indicated that the distribution of BCZT-CuY in PDMS with added rGO was much more uniform than that without rGO. Moreover, its elastic modulus and elongation at the break increased to 4.6 MPa and 250%, respectively, with the introduction of rGO. Apart from a high d 33 at the percolation threshold, the average V OC (1.36 V) and I SC (35nA) achieved by finger tapping BCZT-CuY/rGO-based NGs suggested their considerable potential in harvesting tiny energy. [ABSTRACT FROM AUTHOR]

Owing to the high electron delocalization in 2D ultrathin regions derived from π-d conjugations, electrically conductive metal-organic frameworks (MOFs) are widely used in electronic applications but mostly for rigid devices. The interaction mechanism between conductive 2D MOFs and flexible substrates remains unclear, which cannot meet the increasing demand for next-generation wearable electronics. Herein, conductive copper-benzenehexathiol (Cu-BHT) layers are developed and the underlying mechanisms responsible for the conductivity difference on different representative substrates are explored. It is found that not only the molecular movement inside the polymer but also the fusion between polymer and Cu-MOFs affects the intrinsic conductivity and long-term stability. Therefore, the potential guiding criteria for selecting flexible substrates for conductive 2D MOFs are established. As a demonstration, the Cu-BHT/polymer layer is considered the flexible electrode of triboelectric nanogenerators to harvest energy from water droplets and human motions, verifying the significant role of conductive 2D MOFs in flexible and wearable applications. This study reveals the insights to the potential interaction effect on the conductivity stability of Cu-BHT and advances the development of 2D conductive MOFs in flexible and wearable electronics. [Display omitted] • Flexible and conductive 2D Cu-MOFs (Cu-BHT) layers were synthesized. • Cu-BHT on various substrates exhibited various initial and long-term conductivity. • The interaction mechanism between Cu-BHT and substrates was explored. • Guiding criteria for selecting flexible substrates for 2D MOFs were established. • Cu-BHT was successfully served as flexible electrode of TENGs in multi-fields. [ABSTRACT FROM AUTHOR]

Owing to the limited deformability and restricted scalability of traditional triboelectric nanogenerator (TENG), liquid single-electrode TENG based on graphene oxide dispersion (GO LS-TENG) was developed in this study. The device exhibits high short-circuit current density of 18.61 mA m−2 at contact frequency of 3 Hz, being much higher than that of reported LS-TENG based on NaCl solution (1.8 mA m−2, 2.3 Hz) and liquid metal (8.6 mA m−2, 3 Hz). Moreover, its maximum power density can reach 4.97 W m−2 (1.99 mW, 3 Hz), which is higher than that of a reported single-electrode TENG based on GO solid electrode (3.13 W m−2, 5 Hz). On palm tapping the device, 87 green LEDs connected in series can be lit up. Robustness, durability and reproducibility tests show high stability, sensitivity, and potential use of this device in wearable electronics. This work demonstrates a novel approach to fabricate LS-TENG with simple structure, high output and high sensitivity for use in highly flexible and deformable wearable devices. Image 1 • Novel liquid single-electrode TENG based on GO dispersion is presented. • The maximum power density (power) of GO LS-TENG reaches 4.97 W m−2 (1.99 mW). • 87 green LEDs are lit up by palm tapping the device with electrode size of 4 cm2. • Minute body movement inputs demonstrate great potential in wearable electronics. [ABSTRACT FROM AUTHOR]