Energy Harvester Nanogenerator

Overview

Global sensor development has been played significant importance in the internet of things. The devices mounted with electronics, network connectivity, sensors, and actuators, which enable these devices to exchange and transfer the data. Also, the materials and science technology growth can help develop miniaturized and stretchable electronics on multifunctional devices. In 2007, and 2010, Wang's group was the first introduced piezotronics and piezo‐phototronics fundamental principle, respectively. Those materials with non‐central symmetry properties such as the wurtzite structured ZnO, GaN, and InN can create piezopotential when applying the stress, which has a strong effect on the carrier transport at the interface. A device with piezopotential using as a "gate" voltage to control charge carrier transport in a traditional metal-oxide-semiconductor field-effect transistor (MOS FET).  Our group[ has successfully introduced nanogenerators via using eco-friendly and high-performance materials.

Our strategies:
1. Piezoelectric Nanogenerator

Our group successfully demonstrated a single-microbelt nanogenerator first made using a ZnSnO3 microbelt that generated output power of ∼3 nW under a compressive and releasing strain of 0.8–1%. The ZnSnO3 nanobelts/microbelts were synthesized using a vapor transfer process at 1173 K. An individual ZnSnO3 microbelt was bonded at its ends on a flexible polystyrene substrate as a nanogenerator, which gives an output voltage and current of 100 mV and 30 nA, respectively, corresponding to an energy conversion efficiency of 4.2–6.6% (based on 0.8–1% strain). Our results show that ZnSnO3 microbelts are one of the highly promising materials for lead-free piezoelectric energy harvesting. 

Recent first/corresponding-author publications: 

1. ACS nano 6 (5), 4335-4340 

2. ACS nano 6 (5), 4369-4374 

3. Advanced Materials 24 (45), 6094-6099 

2. Triboelectric Nanogenerator

In this work, we are the first to discover the high-output current density of the triboelectric nanogenerator (TENG) using rice husks as a source material. The raw rice husks (RH) can be directly phase transited into the amorphous SiO2 (RHSiO2) structure with highly nanoporous fragments by the thermal annealing with additional acid hydrolysis process. The RHSiO2-TENG׳s configuration is designed by polytetrafluoroethene (PTFE) and RHSiO2 films, which are chemically and thermally more stable than the metallic film. The pore size around 20–40 nm is widely distributed throughout the SiO2 fragments that possess rich Si–O–Si and OH stretching bonds with strong tendency of repulsing electron because the H atoms have an extremely low electron affinity, leading to the RHSiO2 film exhibits much lower electron affinity when compared with the commercial SiO2 nanoparticles. Rice husk possesses many advantageous traits such as their light weight, low cost, being environmentally friendly, high porosity, excellent robustness, exceptionally chemical and thermal stability for superior corrosion resistance, makes it a valuable material for industrial applications. 

3. Triboelectric Nanogenerator

Our group has successfully demonstrated the self-powered wireless triboelectric vibration sensor, which is made from naturally nanoporous SiO2 particles for allowing the detection of the vibrations and movement in the underwater environment. Interestingly, the nanoporous SiO2 particles are directly prepared from the rice husks (referred to as RHSiO2). Thanks to the enzymatic treatments, RHSiO2 surface potential can be modulated to achieve either extremely low or high electronegativity. Also, by adding fluorinated groups using fluoroalkyl silane (FOTS) treatment to obtain RHSiO2-F, the charge density of the RHSiO2-F triboelectric nanogenerator (TENG) can be enhanced∼56.67-fold as compared to the untreated RHSiO2-TENG. The RHSiO2-F particles are encapsulated in a quartz cube to fabricate a self-powered wireless sensor that can be stabilized for operating in an underwater environment at various temperatures. 

Recent first/corresponding-author publications: 

1. Nano Energy 60, 715-723 

2. Nano Energy 19, 39-47