Publications

Electroadhesion generates an adhesion force using an externally applied power source, which has versatile applications in robotics and material handling. In this study, a self-powered electroadhesion system using enhanced triboelectric nanogenerators (TENGs) to supply power for electroadhesion is presented. By introducing a triboelectric charge supplement channel, the open circuit voltage of the TENG can be significantly boosted by over 10 times, from ∼230 V to more than 3300 V for a single TENG unit, providing sufficiently high voltage for an electroadhesive patch to generate enough adhesion for practical use. The charge supplement channel takes effect through a replenishing mechanism for dissipated charges, maintaining an optimal charge distribution throughout TENG electrodes, which enables the highest open circuit voltage under given surface charge density and device configuration. The fabricated self-powered electroadhesion system shows the ability to manipulate objects of various materials via easy and straightforward operations, demonstrating a great potential for applications in material handling and robotics. Moreover, the voltage enhancement mechanism by the charge supplement channel could be extended to TENGs of other modes, which can provide reliable power sources for various applications that require a high voltage.

Perovskite and semiconductor materials are always the focus of research because of their excellent properties, including pyroelectric, photovoltaic effects, and high light absorption. On basis of this, the design of combining BaTiO3 (BTO) thin films with a GaN layer to form a heterojunction structure with a pyro-phototronic effect has achieved an efficient self-powered BTO/GaN ultraviolet photodetector (PD) with high responsivity and a fast response speed. With cooling and prepolarization treatments, the photocurrent peak and plateau have been enhanced by up to 1348 and 1052%, and the response time of the pyroelectric and common photoelectric current are improved from 0.35 to 0.16 s and from 3.27 to 2.35 s with a bias applied, respectively. The self-powered BTO/GaN PD combined with a pyro-phototronic effect provides a new idea and optimization for realizing ultrafast ultraviolet sensing at room temperature, making it a promising candidate in environmentally friendly and economical ultraviolet optoelectronic devices.

Catalysis is vitally important for chemical engineering, energy, and environment. It is critical to discover new mechanisms for efficient catalysis. For piezoelectric/pyroelectric/ferroelectric materials that have a non-centrosymmetric structure, interfacial polarization-induced redox reactions at surfaces leads to advanced mechanocatalysis. Here, the first flexocatalysis for 2D centrosymmetric semiconductors, such as MnO2 nanosheets, is demonstrated largely expanding the polarization-based-mechanocatalysis to 2D centrosymmetric materials. Under ultrasonic excitation, the reactive species are created due to the strain-gradient-induced flexoelectric polarization in MnO2 nanosheets composed nanoflowers. The organic pollutants (Methylene Blue et al.) can be effectively degraded within 5 min; the performance of the flexocatalysis is comparable to that of state-of-the-art piezocatalysis, with excellent stability and reproducibility. Moreover, the factors related to flexocatalysis such as material morphology, adsorption, mechanical vibration intensity, and temperature are explored, which give deep insights into the mechanocatalysis. This study opens the field of flexoelectric effect-based mechanochemistry in 2D centrosymmetric semiconductors.

Abstract In this study, a ratchet‐like wheel‐based and spring‐assisted sustainable triboelectric nanogenerator (RS‐TENG) is fabricated for an efficient harvesting of rotational motion. The multitooth structure of the ratchet‐like wheel and force of the spring are used to convert the rotational motion induced by mechanical energy in the environment (such as wind energy) into a reciprocating linear motion of the movable parts, making two triboelectric layers of each sub‐triboelectrification unit produce contact–separation motion to achieve power output. The power output of one subunit is ≈0.37 mW at a uniform speed of 60 rpm, and the power output can increase to 6.05 mW by parallel connection of six subunits. The RS‐TENG with parallel connection of six subunits exhibits an open‐circuit voltage of 320 V throughout the 8 h of continuous operation (≈345 600 contact–separation events), reflecting its excellent durability and robustness. The thermometer can be stably powered at a wind speed of 15.5 m s −1 by the rectifier circuit and a 330 µF commercial capacitor. The above experiments show that RS‐TENG can not only harvest the mechanical energy around the environment for self‐powered sensing, but also exhibit an improved output performance and outstanding robustness.

The flow augmentation electromagnetic generator (EMG) with a wind deflector structure has been widely studied. However, the wind energy flowing through the wind deflector of the traditional EMG is not effectively harvesting. As a renewable energy harvesting technology, triboelectric nanogenerator (TENG) has a flexible structural design, making it highly compatible with a wind deflector as a new power generation unit, thus achieving the goal of hybrid generation. In this regard, this work proposes a novel wind-gathering enhanced triboelectric-electromagnetic hybrid generator (WGE-TEHG). Coupling the thin-film vibrating TENG and the wind deflector, the WGE-TEHG not only retains the function of flow augmentation EMG, but also generates additional power output by integrating the wind deflector with TENG structure. The experimental results show that the WGE-TEHG as a generator for harvesting wind energy, which can output a total power of 212.4 mW. In addition, the WGE-TEHG can build a self-powered natural environment micro-meteorological sensing system. It can sense wind direction, wind speed, temperature, and relative humidity in the environment. This research has great application value for the self-powered sensing implementation of hybrid TENG and EMG.

Abstract Motion vector sensors play an important role in artificial intelligence and internet of things. Here, a triboelectric vector sensor (TVS) based on a direct‐current triboelectric nanogenerator is reported, for self‐powered measuring various motion parameters, including displacement, velocity, acceleration, angular, and angular velocity. Based on the working mechanism of the contact‐electrification effect and electrostatic breakdown, a continuous DC signal can be collected to directly monitor moving objects free from environmental electromagnetic signal interference existing in conventional self‐powered TVSs with an alternative‐current signal output, which not only enhances the sensitivity of sensors, but also provides a simple solution to miniaturize the sensors. Its sensitivity is demonstrated to be equivalent to state‐of‐the‐art photoelectric technology by a comparative experiment in an intelligent mouse. Notably, an intelligent pen based on the miniaturized TVS is designed to realize motion trajectory tracing, mapping, and writing on the curved surface. This work provides a new paradigm shift to design motion vector sensors and self‐powered sensors in artificial intelligent and internet of things.

Abstract The emerging direct‐current triboelectric nanogenerator (DC‐TENG) does not need to be rectified and is not restricted by a dielectric breakdown compared with an alternating current TENG (AC‐TENG). Furthermore, the charge density of the DC‐TENG reaches an ultrahigh level far beyond that of the AC‐TENG based on a rational design. However, there are always some electrons remaining on the surface of the dielectric after the breakdown process in the DC‐TENG, and therefore a low charge utilization is obtained. Herein, a simple and universal method is proposed through a double‐layer structure design, that is, a triboelectric layer as the friction layer and an electret layer charged through a surface treatment as the field‐enhancing layer to further improve the output performance of the DC‐TENG, which is inspired by the fable “The Crow and the Pitcher.” Owing to the external field‐enhancing breakdown effect, a double improvement in the breakdown efficiency and output charge density is obtained compared with a conventional DC‐TENG. Moreover, a nearly constant output current has been demonstrated for directly powering electronics without a rectifier. This study provides a universal method for optimizing the output performance of a DC‐TENG.