In order to commercialize the rapidly developing technology of energy harvesters, the following devices need to be developed further for enhancing output performance, flexibility, scalability, facile fabrication, and cheaper price. The composite-based triboelectric nanogenerator (CTENG), which contains the above properties, is a promising technology that has attracted special interest for a decade. Focus has been placed on the hybrid concept between the composite-based piezoelectric nanogenerator (CPENG) and CTENG in order to enhance CTENG efficiency. This study presented a high-performance hybridized CPENG and CTENG device, which operated from the composite film of Ti0.8O2 nanosheets (Ti NSs)/silver nanoparticles (Ag NPs) co-doped BaTiO3 nanopowders (BT NPOs) inside the polydimethyl­siloxane (PDMS) host. The 0.3 vol % of Ti NSs and 1.5 vol % of Ag NPs exhibited the optimum harvesting performance in all compositions, with an output voltage and current density reaching approximately 150 V and 0.32 μA/cm2, respectively. Their harvesting performance was approximately 60 and 32 times higher than that of the CPENG constructed from pure PDMS. In addition, practical demonstration of the proposed device was investigated. The hybridized CPENG and CTENG device could operate in a long-term cyclic operation, charge the capacitor for storing energy, and also drive LEDs to brighten. This work suggested facile device fabrication and made a guideline to develop high-performance nanogenerators, which is crucial for device development and practical usage in the future.

The lepidocrocite-type layered alkali titanate A x M y Ti 2−y O 4 has diverse chemical compositions with variation in charge per formula unit x, the interlayer cation A + , and the intralayer metal M. Despite this multivariable nature, the composition dependence of physical properties is not well explored. We report herein the AC conductivity and the complementary dielectric properties of Cs 0.7 M 0.35 Ti 1.65 O 4 , K 0.8 M 0.4 Ti 1.6 O 4 (M = Zn, Ni), and the mixed-interlayer ion Cs 0.6 K 0.1 Zn 0.35 Ti 1.65 O 4 . For Cs 0.7 Zn 0.35 Ti 1.65 -O 4 , the total AC conductivity is ∼7 × 10 −8 to 2 × 10 −6 S•cm −1 at 200−350 °C, associating with an activation energy E a ∼ 865 meV. Meanwhile, the conductivity of K 0.8 Zn 0.4 Ti 1.6 O 4 is higher by 1 order of magnitude at much lower temperature (25−150 °C) and a smaller E a ∼ 250 meV. This difference originates from the compositional robustness of the cesium-containing samples, contrasting with the sintering-induced changes in the potassium analogues. For the latter, the loss of the interlayer K + ion results in (i) generation of carriers due to charge compensation, (ii) reduction of sheet charge density and weakening of electrostatic attraction, and (iii) widening of the interlayer distance, all contributing to a lower E a in K 0.8 M 0.4 Ti 1.6 O 4 . The angular frequency dependence of conductivity, dielectric permittivity (up to a colossal value of 10 9 ), and dielectric loss follows the universal power law. Our work demonstrates the potential of simple compositional variation for electrical properties tuning, prompting a more in-depth investigation covering a wider range of possible candidates of x, A + , and M in lepidocrocite titanate.

There is a need to develop inexpensive, lightweight, and flexible high‐performance triboelectric nanogenerators (TENGs) from renewable resources. Here, a multifunctional cellulose filter paper (CFP)‐based TENG consisting of dielectric Ti0.8O2 nanosheets (Ti0.8O2 NSs) and conducting Ag nanoparticles (Ag NPs) is prepared by a simple dip coating method. The incorporation of dielectric Ti0.8O2 NSs onto the CFP significantly improves charge generation, while the inclusion of Ag NPs provides an electrically conductive path for charge transportation. The presence of these fillers can be deduced from XRD, SEM, EDS, X‐ray photoelectron spectroscopy, and Raman spectroscopy. Their distribution is visualized in 3D by synchrotron radiation X‐ray tomography. The present CFP‐based TENG provides an output voltage and current density of ≈42 V and ≈1 µA cm−2, respectively with the power density of ≈25 µW cm−2. It is capable of lighting up 40 light‐emitting diode bulbs and charging a 0.22 µF capacitor to 8 V in only 5 s. The developed TENG is also capable of detecting simple human motions, i.e., finger tapping, finger rubbing, and foot trampling. This work offers a facile design of low cost yet efficient paper‐based TENG by dual modification with multifunctional nanomaterials, and also demonstrates its use as a feasible power source that not only drives small electronics, but also scavenges energy from human actions.

The ubiquitous (re)­adsorption of atmospheric water by functional ceramics leads to some applications such as humidity sensing; at the same time, this phenomenon complicates the understanding of the nature of original conducting species. We presented herein the effects of adsorbed water on the electrical properties and charge transport of K0.8Zn0.4Ti1.6O4, Cs0.7Zn0.35Ti1.65O4, and Cs0.6K0.1Zn0.35Ti1.65O4 lepidocrocite-type alkali titanate ceramics. A small amount of atmospheric water (0.02–0.33 mol/mol) is merely adsorbed on the external surface but not intercalated into the interlayer space. In temperature scan experiments, water sorption leads to the dielectric permittivity/loss hysteresis loops, where the values upon cooling are unusually larger than those upon heating. In frequency scan experiments, multiple frequency- and temperature-dependent anomalies are detected. The AC conductivity was fitted to the Jonscher universal power law response (σ′AC = σDC + Aωs) from 101 to 106 Hz and 400–25 °C. We observed an uncommon U-shaped A(T) but an inverted U-shaped s(T), regardless of the interlayer ion, charge per formula unit, or pellet density. These plots allow a qualitative description of (i) the apparent activation energy, (ii) the effective dimension of the conduction pathway, and (iii) the charge carrier concentration, all as a function of the temperature under the influence of atmospheric water. Our physical interpretation is potentially applicable to other systems, providing insights into the (unintentional) water-induced conductions and complementing rigorous but time-consuming investigations by controlled humidity experiments.

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This research successfully demonstrated a facile, effective and scalable preparation of BaTiO3 nanowires (BT-NWs) via the template-free salt flux assisted method. High-performance lead-free flexible piezoelectric nanogenerator using BT-NWs was proposed in this work.

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This study introduced a new facile roughness fabrication method for the triboelectric nanogenerator (TENG). Solid salt was applied to induce the macroscopic triangle-like roughness on material surface in which the density could be controlled. Additionally, the roughness effect on the electrical property of TENG was investigated. Three roughness fabrication techniques were designed to make textures for TENG materials by producing certain roughness formations. The highest electrical outputs (voltage and current) were found in the device designed for matching the roughness textures. Both output voltage and current increased by about 3 times when compared with the non-textured device. The increase of electrical outputs of TENG was due to the increase of roughness area, leading to more triboelectric charge generation. This work presented a new feasible fabrication technique and suggested a scheme to engineer the roughness for enhancing the TENG performance, which is crucial for TENG-based device development and practical use in the future.