Photo-stimulated triboelectric generation

DNA-Nanocrystal Assemblies for Environmentally Responsive and Highly Efficient Energy Harvesting and Storage

Natural polymer-based and self-powered bioelectronic devices are attracting attention owing to an increased interest in human health monitoring and human-machine interfaces. However, obtaining both high efficiency and multifunctionality from a single natural polymer-based bioelectronics platform is still challenging. Here, molybdenum disulfide (MoS₂ ) nanoparticle- and carbon quantum dot (CQDs)-incorporated deoxyribonucleic acid (DNA) nanocomposites are reported for energy harvesting, motion sensing, and charge storing. With nanomaterial-based electrodes, the MoS₂ -CQD-DNA nanocomposite exhibits a high triboelectric open-circuit voltage of 1.6 kV (average) and an output power density of 275 mW cm^-2 , which is sufficient for turning on hundred light-emitting diodes and for a highly sensitive motion sensing. Notably, the triboelectric performance can be tuned by external stimuli (light and thermal energy). Thermal and photon energy absorptions by the nanocomposite generate additional charges, resulting in an enhanced triboelectric performance. The MoS₂ -CQD-DNA nanocomposite can also be applied as a capacitor material. Based on the obtained electronic properties, such as capacitances, dielectric constants, work functions, and bandgaps, it is possible that the charges generated by the MoS₂ -CQD-DNA triboelectric nanogenerator can be stored in the MoS₂ -CQD-DNA capacitor. A new way is presented here to expand the application area of self-powered devices in wearable and implantable electronics.

Controlling Surface Charge Generated by Contact Electrification: Strategies and Applications

Contact electrification is the phenomenon in which charge is generated on the surfaces of materials after they come into contact. The surface charge generated has traditionally been known to cause a vast range of undesirable consequences in our lives and in industry; on the other hand, it can also give rise to many types of useful applications. In addition, there has been a lot of interest in recent years for fabricating devices and materials based on regulating a desired amount of surface charge. It is thus important to understand the general strategies for increasing, decreasing, or controlling the surface charge generated by contact electrification. Herein, the fundamental mechanisms for influencing the amount of charge generated, the methods used for implementing these mechanisms, and some of the recent interesting applications that require regulating the amount of surface charge generated by contact electrification, are briefly summarized.

A spring-assisted hybrid triboelectric-electromagnetic nanogenerator for harvesting low-frequency vibration energy and creating a self-powered security system

With the rapid development of portable electronics, exploring sustainable power sources is becoming more and more urgent. Utilizing a nanogenerator to harvest ambient mechanical energy could be an effective approach to solve this challenge. In this work, a novel spring-assisted hybrid nanogenerator (HG) consisting of a triboelectric nanogenerator (TENG) and an electromagnetic generator (EMG) was developed for harvesting low-frequency vibration energy. The results show that the TENG with a PTFE surface nanostructure has better output performance than that without the nanostructure. The effect of operating frequency on the open-circuit voltage and short-circuit current of the TENG and EMG is systematically investigated. Under a 2 Hz operating frequency, the EMG and TENG are able to produce a peak power of about 57.6 mW with a resistive load of 2000 Ω and 1682 μW with a resistive load of 50 MΩ, respectively. The impedance matching between the TENG and EMG can be realized by using a transformer to reduce the impedance of the TENG. The charging performance of the HG is much better than that of the individual EMG or TENG. The HG enabled us to develop a self-powered safety system and to power LEDs, and drive some electronic devices. The present work provides a superior solution to improve the output performance of the HG for harvesting low-frequency vibration energy.