Modulating ZnO Growth Structures for Maximum Power Output of Hybrid Piezo/Triboelectric Nanogenerator

Abstract

Hybrid piezo/triboelectric nanogenerators (H-P/TENGs) are developed to compensate the drawbacks of a single nanogenerator by synergizing high triboelectric output voltage and piezoelectric output current in continuous contact-separation cycles. In particular, piezoelectric zinc oxide (ZnO) has been widely used due to its excellent orientation along the c-axis and tunable growth structures. Herein, various growth structures of ZnO, unoriented, oriented, and hierarchical structures, are incorporated in H-P/TENGs, enhancing their power densities from 6 to 17 times. Particularly, oriented ZnO nanorod/ PVA (ZnR) achieves a maximum power density of 15.9 W m −2 (≈17-fold increment compared to pristine PVA). The highly oriented ZnO growth along the c-axis enables large deformation upon a vertical compression, subsequently generating a large piezoelectric polarization. Moreover, the enhancement mechanism via piezoelectric polarization is elucidated using a modified overlapped electron cloud model supported with Kelvin probe force microscopy measurements. The polarization of ZnO nanocomposites enlarges the difference in the highest electron energies (ΔE) between the two triboelectric layers, driving more electrons to transfer during contact electrification, thereby enriching their surface charge densities. This study highlights the significance of growth structure control in maximizing the piezoelectric responses of ZnO, consequently improving the output performances of H-P/TENGs.

A hybrid piezoelectric and triboelectric nanogenerator with lead-free BZT–BCT/PDMS composite and PVA film for scavenging mechanical energy

“…eqn (1) is used to approximate the surface charge density of the polymer composite films. 44 where σ and ε r are the surface charge density and relative dielectric constant of the polymer composite film, while the ε 0 is the vacuum permittivity (8.854 × 10 −12 F m −1 ), V is the open-circuit voltage measured using the polymer composite film, and d is the separation distance between the two triboelectric layers. The calculated surface charge density of the pristine, forward and reverse poled composite films is shown in Fig.…”

“…Herein, an overlapping electron cloud (OEC) model is adopted to explain the formation of charges during the contact electrication in H/P-TENG. 28,44,50 This model is able to illustrate how charges are formed within the H/P-TENG during contact electrication and how factors like piezoelectric inclusion and the poling orientation of the PDMS/BZT-BCT polymer composite lm affect the charge generation. Fig.…”

A passive optical fibre sensor based on Fabry‐Perot interferometry for bipolar electrostatic monitoring of insulating dielectrics

“…Concerning to an improvement in sensitivity of the sensor, the performance of the electromechanical transducer could be improved by increasing the d 33 according to Equation (3). Thus, the development and research of novel functional dielectrics with higher electromechanical conversion performance could contribute to the research of the electrostatic sensor [21,30]. For example, the thermodynamic -685 study of the electromechanical transducer can solve the problems in varying temperature environment for engineering applications.…”

“…In recent years, extensive studies have been conducted on the optical fibre sensors based on the principle of Fabry-Perot (F-P) interference in the partial discharge detection of the transformer due to their merits of high sensitivity, high accuracy, high signal-to-noise ratio [14][15][16][17][18][19][20] etc. Meanwhile, the development of advanced functional materials enables the development of the sensor for higher performance [21]. As shown in Figure 1, an optical fibre electrostatic sensor based on the principle of F-P interference is developed and fabricated in order to overcome the limitations of the Kelvin vibrating probe and the optical Pockels technology.…”

Enhanced nanogenerator by embedding lead-free double perovskite Cs2AgBiBr6 in polymer matrix for hybrid energy harvesting

“…In some recent studies, CsPbI 2 Br-decorated PVDF nanofibers 27 possessed the most desirable morphology and functionality with a V oc of 8.3 V and I SC of 1.91 mA. Considering the PE effect of PVDF, using the above functional materials to establish HENGs 28,29 could be regarded as a progressive scheme to achieve an efficient energy conversion mode. F. Jiang 30 et al used Cs 3 Bi 2 Br 9 as a functional filler to prepare a poly(vinylidene fluoride-cohexafluoropropylene) (PVDF-HFP)-based composition; the resulting HENG achieved an enhanced V oc and short-current density (J sc ) of 400 V and 1.63 mA cm À2 .…”