Xianming He

A nanogenerator for harvesting airflow energy and light energy

Harvesting airflow energy and light energy from the ambient environment to build a self-powered system is attractive and challenging work. In this article, an airflow-induced triboelectric nanogenerator (ATNG) has been fabricated that converts wind energy to alternating electricity. The mechanism of ATNG has also been illustrated. The performance of ATNGs with different sizes was studied, from which we discovered that the ATNG (size: 1 cm × 3 cm, electrode gap: 1.5 mm) could easily collect energy from a gentle wind (5.3 m s−1). Due to the relatively high alternating electricity frequency (179.5–1220.9 Hz), an approximately stable output power (of up to 1.5 mW) was obtained from the ATNG (size: 1 cm × 3 cm, electrode gap: 0.5 mm) with 8.35 μC of charge transferred per second. Meanwhile, the fabricated wind energy harvesting device was used to drive 46 commercial green light-emitting diodes (LEDs) connected in series and charge a 220 μF capacitor to 2.5 V over 50 s. When combined with a dye-sensitized solar cell (DSC), the device can individually and simultaneously harvest wind and light energy. This shows the potential applications of this ATNG in self-powered systems.

Enhancing Performance of Triboelectric Nanogenerator by Filling High Dielectric Nanoparticles into Sponge PDMS Film

Understanding of the triboelectric charge accumulation from the view of materials plays a critical role in enhancing the output performance of triboelectric nanogenerator (TENG). In this paper, we have designed a feasible approach to modify the tribo-material of TENG by filling it with high permittivity nanoparticles and forming pores. The influence of dielectricity and porosity on the output performance is discussed experimentally and theoretically, which indicates that both the surface charge density and the charge transfer quantity have a close relationship with the relative permittivity and porosity of the tribo-material. A high output performance TENG based on a composite sponge PDMS film (CS-TENG) is fabricated by optimizing both the dielectric properties and the porosity of the tribo-material. With the combination of the enhancement of permittivity and production of pores in the PDMS film, the charge density of ∼19 nC cm(-2), open-circuit voltage of 338 V, and power density of 6.47 W m(-2) are obtained at working frequency of 2.5 Hz with the optimized film consisting of 10% SrTiO3 nanoparticles (∼100 nm in size) and 15% pores in volume, which gives over 5-fold power enhancement compared with the nanogenerator based on the pure PDMS film. This work gives a better understanding of the triboelectricity produced by the TENG from the view of materials and provides a new and effective way to enhance the performance of TENG from the material itself, not just its surface modification.

Flexible interdigital-electrodes-based triboelectric generators for harvesting sliding and rotating mechanical energy

Triboelectric generators have attracted considerable attention due to their rapidly improved electromechanical conversion efficiency. It is a great challenge to design a triboelectric generator to enable practical and effective operations. In this paper, we present a flexible interdigital-electrodes-based triboelectric generator (FITG) for harvesting sliding and rotating mechanical energy. When a film of flexible interdigital electrodes is placed on a plane, it can be used for harvesting sliding energy. When the film of the flexible interdigital electrodes is rolled into a cylinder, it can be used for harvesting rotating energy. In sliding mode, the maximum open-circuit voltage, short-circuit current and peak power density reach up to 400 V, 120 μA (10 mA m−2) and 13 W m−2, respectively, under a sliding velocity of 3.95 m s−1, which can be used to light tens of light-emitting diodes (LEDs) and to charge a commercial capacitor to 7.2 V within 35 s. The FITG can harvest the mechanical energy of mouse operation and traditional printing. In rotating mode, the maximum output voltage of the generator reaches as high as 1020 V at a rotating speed of 240 rpm. The FITG with interdigital electrodes on a flexible substrate has the advantages of light weight, resistance to wear, multifunction and high output power.

Nanorod-aggregated flower-like CuO grown on a carbon fiber fabric for a super high sensitive non-enzymatic glucose sensor

A novel and exceptionally sensitive glucose biosensor based on nanorod-aggregated flower-like CuO grown on a carbon fiber fabric (CFF) is developed for glucose detection, which is prepared by a simple, fast and green hydrothermal method. The electron transfer resistance of the CuO/CFF electrode on the interface between the electrode and the electrolyte is as low as 12.79 Ω as evaluated by electrochemical impedance spectroscopy. A cyclic voltammetry study reveals that the CuO/CFF electrode displays an excellent electrocatalytic activity toward the direct oxidation of glucose. Besides, chronoamperometry demonstrates a high sensitivity of 6476.0 μA mM-1 cm-2 at an applied potential of 0.45 V (vs. Ag/AgCl), with a fast response time and a low detection limit of only 1.3 s and ∼0.27 μM, respectively. In addition, the glucose sensor has high reproducibility with a relative standard deviation (R.S.D.) of 1.53% over eight identically fabricated electrodes and long-term stability with a minimal sensitivity loss of ∼9.9% over a period of one month as well as excellent anti-interference ability. Importantly, the CuO-CFF composite has such good flexible characteristics and can be fabricated into flexible electrodes for application in various complicated circumstances. This work presents a new strategy to achieve highly sensitive glucose sensors with flexibility by growing glucose electroactive nanostructure materials directly on multichannels and highly conductive carbon fiber fabrics.

Enhanced output-power of nanogenerator by modifying PDMS film with lateral ZnO nanotubes and Ag nanowires

In this paper, a nanogenerator based on flexible polydimethylsiloxane (PDMS) film modified with semiconductor zinc-oxide (ZnO) nanotubes and conductive Ag nanowires is designed and fabricated. The modified PDMS film consists of semiconductor ZnO nanotubes distributed on a dielectric PDMS film with conductive Ag nanowires covered on the surface of the ZnO nanotubes and another thin PDMS layer encapsulated on the top, which forms the structure of PDMS/Ag/ZnO/PDMS. The Ag nanowires act as multi-antennal electrodes and play an important role in improvement of output power. The performance of the nanogenerator with different modified PDMS films is investigated under different measurement conditions. The output current density and power density of the generator under periodic stress (20 N) are 10 μA cm and 1.1 mW cm−2, respectively. The instantaneous output current peak can reach as high as 115 μA (23.75 μA cm−2) under a pressure of 90 N which can be used to light up 99 commercial green LEDs connected in series. The output power of this modified PDMS-based nanogenerator is much higher than that of previously reported PDMS-based nanogenerators, demonstrating excellent structural advantages.