Triboelectric Generator Research Articles

Gas-solid two-phase flow triboelectric generator for powder triboelectrification energy collection and road early warning

With the rapid development of modern industrial processes, electrostatic safety issues caused by powder in production and daily life have attracted people's attention. Since powder is small in size and easily agglomerates, it is difficult to observe or design devices to monitor the electrostatic process generated by powder. Herein, a continuous gas-solid two-phase flow triboelectric nanogenerator (GS-TENG) was developed to harvest triboelectricity from the collision process between the powder-air flow and the solid surface. Compared with the signals under non-continuous airflow, the short-circuit current and output voltage signals generated under continuous airflow impact exhibit an unidirectional direct current peak characteristic. Additionally, in order to analyze the relationship between motion of powder airflow and the triboelectric signals, the two-phase flow more comprehensively, a high-speed camera was used to record motion during the charge generation process. Results showed that 3 mm nylon sphere generated normal alternating current signals upon contact and separation from PTFE, while nylon power with the diameter of about 30 µm produced direct current triboelectric signals owing to the effect of point discharge. At a wind speed of 32 m/s, 5 cm distance, 90° impact angle, the short-circuit current and output voltage can reach the maximum values of 20 µA and 130 V, respectively, which can serve as a power source sufficient to power 63 commercial LEDs. Based on the gas-solid two-phase flow triboelectric nanogenerator, a self-powered road warning lights was designed, indicating application prospects in dusty weather.

Asymmetrical Schottky Junction Built by Metal/Conducting Polymer Targeting Efficient Flexible Direct Current Tribovoltaic Generator

Direct current (DC) from mechanical energy built on the tribovoltaic effect is promising for the development of self‐powered flexible electronics. A semiconductor triboelectric generator is one of the optimized solutions for DC output. However, it remains underutilized because of its low output power and insufficient insight into the fundamental principles of charge generation and transport at dynamic interfaces. Herein, a flexible fabric‐based DC generator that relies on a metal–semiconducting polymer interface constructed by an asymmetric Schottky junction between a poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS)‐coated fabric and an aluminum (Al) foil is reported. The dependence of the electrical output performance of the device on the doping carrier concentration using different types of PEDOT:PSS to modulate the Schottky barrier height, validating both the work function and conductivity of the triboelectric material, which plays a fundamental role in DC generation, is explored. A large work function difference is required to create a high built‐in electric field for efficient separation of electron–hole pairs. Decent conductivity also fulfills an integral role in the innate carrier‐transport capability. Accordingly, an open‐circuit voltage (Voc) of 800 mV, a short‐circuit current (Isc) of 80 μA, and a power density of 6.7 mW cm−2 are yielded simultaneously.

Contact Area of Electrification Materials Relating to Triboelectric Generators: A Comparative Study

Triboelectric generators (TEGs) stemming from the triboelectric phenomena, are promising for energy harvesting due to their high output power and efficiency. Analysis of the tribo material selection for TEGs has suggested that energy generation is linked to heterogeneous and homogeneous materials found at opposite ends of the triboelectric series. Current research has identified that the triboelectric phenomenon also exists from contact between identical tribo materials with the advancement of surface modification. However, a comparison of composite and identical homogeneous TEGs has yet to be reported. For this research, organic polymer membranes Polyamide-6 (PA6) and Polytetrafluoroethylene (PTFE) were evaluated. The membranes were cut into samples of varying dimensions to build three sets of TEGs for comparison. Two identical sets of four sampled TEGs were fabricated using the same membrane (i.e., PA6-PA6 and PTFE-PTFE); in contrast to a composite set of four sampled TEGs made from the two distinct membranes (i.e., PA6-PTFE). By repeatedly sampling the TEGs in sliding mode at a speed of 0.2 m/s and with a vertical force of 9.8 N an open circuit voltage (Voc) was generated and recorded. As a result, the Voc of the identical TEGs was compared to the Voc of the composite TEG in which the tribo materials are located at opposite ends of the triboelectric series. It was also observed that the Voc increased almost linear in relation to the surface area of the TEGs; thus, suggesting that the surface area of the TEG can influence significantly the Voc to a great extent.Graphical abstract

The Effect of an Aluminium Disc Rotator on Polyvinyl Chloride (PVC) Material using 360° Lateral Sliding Disc Triboelectric Generator (TEG)

Triboelectric generatorshave the ability to harvest energy from human activities, mechanical vibration, and other sources to drive minor electronic devices.In many circumstances, charges created from a triboelectric process are referred to as a negative effect or waste energy. Here, this paper will demonstrate an approach of the charging process in friction with a rotator and stator to investigate the effects of rotating speed and the different thickness of electrification to the output voltage. The 360° lateral sliding disc triboelectric generator (TEG) fabricated by connecting an Aluminium disc to the motor as a rotator, while a Polyvinyl Chloride (PVC) sheet placed at the top of an acrylic coated by a copper electrode served as a stator. PVC material with different thicknesses (0.2, 0.5 and 0.7 mm) and grit sizes were used (P500, P1000 and P1500) and prepared prior to the experiment. Thus, three different rotational speeds (500, 1000 and 1500 rpm) were monitored using a tachometer to standardize the speed for each set of experiment. Such as a TEG at 1500 rpm on a 0.2 mm thick sample with P500 grit size modification delivers a maximum voltage output, VRMSof 13.8 mV, with the maximum calculated current of 69 µA and the maximum power density of 0.485 mW/m2.

Wear-Resistant Smart Textiles Using Nylon-11 Triboelectric Yarns.

The ever-increasing demand for self-powered systems such as glucose biosensors and mixed reality devices has sparked significant interest in triboelectric generators, which hold large potential as renewable energy solutions. Our study explores new methods for integrating energy-harvesting capabilities into smart textiles by developing strong and efficient yarns that can convert mechanical energy into electrical energy through a triboelectric effect. Specifically, we focused on Nylon-11 (PA11), a material known for its crystalline structure well-suited for generating a powerful triboelectric response. To achieve this, we created triboelectric yarns by electrospinning PA11 fibers onto conductive carbon yarns, enabling energy-harvesting applications. Extensive testing demonstrated that these yarns possess exceptional durability, surpassing real-life usage requirements while experiencing minimal degradation. Additionally, we developed a prototype haptic device by interweaving tribopositive PA11 and tribonegative poly(vinylidene fluoride) (PVDF) triboelectric yarns. Our research has successfully yielded durable and efficient yarns with strong energy-harvesting capabilities, opening up possibilities for integrating smart textiles into practical scenarios. These technologies are promising steps to achieve greener and more reliable self-powered systems.

Self-Powered and Self-Sensing Blue Carbon Ecosystems by Hybrid Fur Triboelectric Nanogenerators (F-TENG)

Seaweeds are critical in the blue carbon ecosystem; however, light limitation is a bottleneck for seaweed farming, especially in turbid waters. Utilizing triboelectric generators (TENG) to provide light for seaweeds is a promising solution for enhancing seaweed growth and increasing their carbon sequestration rate. Here, we develop the hybrid fur TENG (F-TENG) designed with the fur-brush TENG (FB-TENG) and fur-sphere TENG (FS-TENG) to enhance the growth of seaweeds and achieve the self-powered and self-sensing blue carbon ecosystems. The FB-TENG exhibits a multistage step signal response, enabling the determination of the fur brush's relative displacement, which, in turn, reflects the impact of marine flow on the device in the vertical direction. The FS-TENG is employed for marine flow energy harvesting in the horizontal direction to illuminate LED lights and stimulate seaweed growth. The FS-TENG with four power generation units achieves the peak current, transferred charge, and instantaneous output power values of 29.9 μA, 0.66 μC, and 89.3mW, respectively. The seaweed cultivation experiments are conducted to demonstrate the significantly enhanced performance of the self-powered and self-sensing blue carbon ecosystems with respect to the growth of the juvenile seaweed by using the hybrid F-TENG as a self-powered light supply. A remarkable increase is observed in both the average net biomass accumulation and linear growth rate, reaching up to 10.83 ± 0.16% day-1 and 9.12 ± 0.68% day-1, respectively. Eventually, experiments are conducted in a circulating water tank to showcase the remarkable energy harvesting capabilities of the hybrid F-TENG. The reported hybrid F-TENG provides a promising solution for establishing self-powered and self-sensing blue carbon ecosystems.

Arbitrary skin metallization by pencil-writing inspired solid-ink rubbing for advanced energy storage and harvesting

The development of a durable metallic coating on diverse substrates is both intriguing and challenging, particularly in the research of metal-conductive materials for applications such as batteries, soft electronics, and beyond. Herein, by learning from the pencil-writing process, a facile solid-ink rubbing technology (SIR-tech) is invented to address the above challenge. The solid-ink is exampled by rational combination of liquid metal and graphite particles. By harnessing the synergistic effects between rubbing and adhesion, controllable metallic skin is successfully formed onto metals, woods, ceramics, and plastics without limitation in size and shape. Moreover, outperforming pure liquid-metal coating, the composite metallic skin by SIR-tech is very robust due to the self-lamination of graphite nanoplate exfoliated by liquid-metal rubbing. The critical factors controlling the structures-properties of the composite metallic skin have been systematically investigated as well. For applications, the SIR-tech is demonstrated to fabricate high-performance composite current collectors for next-generation batteries without traditional metal foils. Meanwhile, advanced skin-electrodes are further demonstrated for stable triboelectricity generation even under temperature fluctuation from −196 to 120 °C. This facile and highly-flexible SIR-tech may work as a powerful platform for the studies on functional coatings by liquid metals and beyond.

Clapping triboelectric nanogenerators as self-powered, frequency-insensitive and gravity-independent vibration sensors

Self-powered vibration sensors have the potential to greatly improve vibration monitoring of remote and hard-to-access structures by providing cost-effective and energy-efficient solutions. One promising type of sensors based on the triboelectric generator mechanism has shown significant advantages over other self-powered sensors, including better energy conversion efficiency and high output voltage. However, the majority of the recently reported triboelectric powered sensors exhibit strong frequency dependence, being mostly effective under low frequency vibrations. To address these issues, herein we present a novel design of self-powered vibration sensors based on the clapping mode of a triboelectric nanogenerator (TENG). The sensor, consisting of two tribo-layers made of regular copy paper and PTFE that are clamped together by springs, is able to achieve a high sensitivity of 10.8 mV/g and a broad frequency range from 50 to 8000 Hz with a flat frequency response of ±5 dB, regardless of the inclination angle between the contacting surfaces and gravity. The sensor exhibits high linearity (0.9999) and stability over six days and 400,000 cycles. Furthermore, computational modelling has been conducted to understand the nonlinear clapping phenomenon and the influence of clamping force, proof mass and spring stiffness on the sensor's performance. The potential of the clapping TENG sensor is demonstrated through two different applications such as music recording and diagnosis of the loosing of bolts in a rotating machine. Its superior performances, along with low cost, compact design, and electromagnetic shielding, make it a promising candidate for battery-free high-frequency vibration sensors in practical vibration measurement applications.

Innovative design: Flexible conductive natural rubber electrode sheets with triboelectric generator activated by wheel rotation

Efficient consumption and clean energy management play a vital role in green energy. To be a part of this effort. Among the materials explored, flexible conductive electrodes utilizing triboelectric phenomena and unique properties of natural rubber composites have demonstrated a great potential for mechanical-to-electrical energy conversion. Fabrication process involves modifying natural rubber latex by incorporating conductive fillers such as carbon black, Ketjen black, and multiwall carbon nanotubes. The modified flexible conductive natural rubber sheets (CNRs) are then characterized for their structural and electrical properties. This structural arrangement significantly reduces the electrical resistance of the NR sheets. The incorporation of the MWCNT fillers leads to an increase in dielectric constant of CNRs. These properties are optimized via a proper design of the conductive natural rubber sheet triboelectric nanogenerator (CNRS-TENG). To enhance charge accumulation, polytetrafluoroethylene (PTFE) film is applied to the bottom surface of the CNRs. The CNRS-TENG are integrated into a wheel rotation generator setup. The output performance of the wheel rotation generator is influenced by the rotational speed as well as the arrangement of phases and segments. This work demonstrates that CNRs can be integrated with flexible electronic and other energy harvesting devices, opening possibilities for multifunctional clean energy solutions.

System Architecture for Conditioning the Asymmetric and High Crest Output of Triboelectric Generators

System Architecture for Conditioning the Asymmetric and High Crest Output of Triboelectric Generators

Continuous fabrication of core-sheath fiber for strain sensing and self-powered application

Fiber-based sensor based on the core-sheath structure has drawn increasing attention in the strain sensing and self-powered fields because of its various advantages (e.g., lightweight, small size, flexibility and ease of weavability into soft textile, etc.). However, it still has been challenging to continuously fabricate core-sheath fiber with good interfacial interaction. Herein, a core-sheath fiber was continuously fabricated by melt co-extrusion molding method, whose sheath layer and core layer are respectively pure polystyrene polybutadiene polystyrene (SBS) and SBS/multi-walled carbon nanotubes (SBS/MWCNTs) composite. In view of this, exhibits good compatibility occurs between core layer and sheath layer because they share the same SBS phase. Moreover, with the help of sheath layer, core layer can be effectively prevented the environmental damage. Fiber strain sensor based on such core-sheath fiber exhibits a higher sensitivity (i.e., GF = 106341), wider working range (strain of 0–200 %) and shorter response time (50 ms), which can further perform underwater communication and underwater motion monitoring. Furthermore, based on such core-sheath fiber, fiber triboelectric generator (F-TENG) and textile triboelectric generator (T-TENG) have been successfully developed and they can respectively serve as self-powered bionic whisker (SPBW) and mechanical energy harvester (MEH). This study provides a facile, low-cost, continuous and environmentally friendly method to fabricate core-sheath fiber, paving a new pathway to develop fiber with strain sensing and self-powered sensing performance.

High-Performance Hybrid Triboelectric Generators Based on an Inversely Polarized Ultrahigh β-Phase PVDF

High-Performance Hybrid Triboelectric Generators Based on an Inversely Polarized Ultrahigh β-Phase PVDF

(Invited) advantageous Utilization of Triboelectricity Based Electric Signals for Energy Harvesting and Self-Powered Sensing

Triboelectric signal generation, which is originated from sequential contact and separation of two different materials including liquid, is highlighted as a novel mechanism for development of various types of energy harvesters as well as self-powered sensors. Unlike most of the regarding research as materials and chemistry oriented approaches, the role of the classical mechanics in aforementioned triboelectric signal generation is introduced. By adopting the ordinary power transmission unit into the triboelectricity based energy harvester, called triboelectric nanogenerator (TENG), the output performance can be significantly increased and such remarkable increase allows us to use the triboelectric signal generation mechanism more practically. As one of the representative examples, the effective biomechanical energy harvesting via triboelectric signal generation is introduced. Along with it, the advantageous effect of the triboelectric signal generation on the operation of the classical mechanical elements, which are frequently employed for direct power transmission, is proposed. In this regard, the self-triggered mechanical sensors, which enable us to inform various characteristics of the machine components, are proposed. Since the electric signal can be generated without any other external power sources, the present sensor can be considered as self-triggered. Gear and brake are one of the most ordinary and effective components for transmitting mechanical power as a core component of machines. Given that the operation of the gear and brake in power transmission is based on sequential contact and separation between two separated components, the simple modification of the outermost surface of the conventional machine components enables us to spontaneously generate triboelectric signal during ordinary power transmission. The present approach to utilize state-of-the-art triboelectric signal generating mechanism could open new application fields by converging it with the classical mechanics.

(Invited) novel Charged Interfaces for Catalysis and Energy Conversion

Charged interfaces are ubiquitous in many research fields such as electrochemistry, catalysis, and energy chemistry, and are key places where physical and chemical processes occur. The charged interface structure can also be affected by external fields such as light, electricity, and force, and becomes the key to regulating chemical reactions. It is of great significance for the development of surface and interface science, electrochemistry, catalysis and energy science to deeply understand the physical and chemical reaction process and mechanism of various charged interface systems, and to clarify the interaction between interface structure and reacting species. It is extremely challenging to rationally design, construct, and characterize various novel charged interfaces, and then comprehensively and deeply study their physical and chemical processes and mechanisms. By constructing new charged interface structures such as solid/solid triboelectric interface, micro-droplet charged liquid/gas interface, and metal/two-dimensional material charged interface, we study the reaction process and mechanism of the charged interface and develop new energy conversion pathways. A series of innovative research results: Discovered a new mechanism of triboelectric power generation, expanding the new direction of charged interface structure in energy conversion; established and developed epitaxial growth modes of various interface structures; accurately characterized the electron transport of charged interface structure and surface charge distribution and other physical and chemical properties. We have developed new systems such as solid/dielectric/liquid charged interfaces based on electrodes/dielectric layers/electrolytes and liquid/gas charged interfaces based on microdroplets, and explored new applications in energy conversion and electrocatalysis. Applying a voltage to the electrode/dielectric layer/electrolyte interface can polarize the dielectric layer and adsorb ions in the electrolyte, forming a special "sandwich" electric double layer. Different from the solid/solid charged interface formed by triboelectrification or light excitation, this is a new solid/dielectric/liquid charged interface system based on electrostatic adsorption. Based on this interface system, a new nanoscale power generation device is designed, which can effectively convert mechanical energy into electrical energy, and has high output performance. A new liquid/gas charged interface based on micro-droplets was constructed by means of electrospray, a new strategy for confining the liquid/gas charged interface was proposed, and a high-performance electrolytic water catalyst was prepared. The physical and chemical mechanism of accelerated chemical reactions at the liquid/gas charged interface is revealed, and the desolvation effect and interface confinement effect are proved to be effective ways to construct defect-rich electrocatalysts.

Wearable Foot Pressure Sensing System for Fallen Arch Analysis

The main purpose of this research is to distinguish the extent of fallen arch by analyzing the center of foot pressure when people are walking. Fallen arch is often called the flatfoot. There are two types of flatfoot, the rigid flatfoot and the acquired flatfoot. The rigid flatfoot is because of bones formation, and people often get rigid flatfoot when they are young. The acquired flatfoot occurs usually on adults because of the walking postures, shoe types, weight and so on. Since these reasons, it is possible that we can improve or prevent the acquired flatfoot through wearing orthotic insoles or changing the walking posture. That’s the reason why our research is focusing on the acquired flatfoot. In this research, we develop a wearable foot pressure sensing system, consist of wireless Bluetooth transmit module and sensing insoles. The wireless Bluetooth transmit module helps to accomplish our measuring system as a wearable device. The sampling rate of wireless Bluetooth transmit module is one thousand samples per second. As a result, we can get a very detailed track on the walking motions. The sensing insoles are made of triboelectric nanogenerator (TENG) technology. The working principle of TENG is based on the coupling of triboelectric effect and electrostatic induction. Depending on the property of triboelectric generation of different materials and through continuous contact and separation, there is an electrostatic induction and current flow between the triboelectric layers and the electrodes, thus causing the potential difference. By detecting the potential differences, we can get the signals of pressure, so we can calculate the center of foot pressure and compare with the standard to check which walking posture we can apply to improve the fallen arch and find out where the center of foot pressure should be placed. Using this system, we can get the real-time foot pressure information and collect the information anytime and anywhere, accomplishing the smart medical.

Modulating the Configurations of "Gel-Type" Soft Silicone Rubber for Electro-Mechanical Energy Generation Behavior in Wearable Electronics.

Electro-mechanical configurations can be piezo-electric transducers, triboelectric generators, electromagnetic induction, or hybrid systems. Our present study aims at developing energy generation through the piezoelectric principle. Gel-type soft SR with Shore A hardness below 30 was used as a versatile material for an elastomeric substrate. Also, multi-wall carbon nanotube (MWCNT), and diatomaceous earth (DE) were used as reinforcing fillers. This "gel-type" soft SR has crosslinking polymer networks with silicone encapsulated within its structure. Mechanical properties such as modulus or stretchability are of utmost importance for such devices based on "gel-type" soft. From the experiments, some of the mechanical aspect's values are summarized. For example, the stretchability was 99% (control) and changes to 127% (3 phr, MWCNT), 76% (20 phr DE), and 103% (20 phr hybrid). From electro-mechanical tests, the output voltage was 0.21 mV (control) and changed to 0.26 mV (3 phr, MWCNT), 0.19 mV (20 phr DE), and 0.29 mV (20 phr hybrid). Moreover, from real-time biomechanical human motion tests in "gel-type" soft-based composites, a relationship among output voltage from machine to human motions was established. Overall, these configurations make them promising against traditional portable devices such as batteries for small power applications such as mobile phones.

Research Progress on the Application of Triboelectric Nanogenerators for Wind Energy Collection.

The escalating global energy demand necessitates the exploration of renewable energy sources, with wind energy emerging as a crucial and widely available resource. With wind energy exhibiting a vast potential of approximately 1010 kw/a per year, about ten times that of global hydroelectric power generation, its efficient conversion and utilization hold the promise of mitigating the pressing energy crisis and replacing the dominant reliance on fossil fuels. In recent years, Triboelectric Nanogenerators (TENGs) have emerged as novel and efficient means of capturing wind energy. This paper provides a comprehensive summary of the fundamental principles governing four basic working modes of TENGs, elucidating the structures and operational mechanisms of various models employed in wind energy harvesting. Furthermore, it highlights the significance of two major TENG configurations, namely, the vertical touch-separation pattern structure and the independent layer pattern for wind energy collection, emphasizing their respective advantages. Furthermore, the study briefly discusses the current strengths of nano-friction power generation in wind energy harvesting while acknowledging the existing challenges pertaining to device design, durability, operation, and maintenance. The review concludes by presenting potential research directions and prospects for triboelectric nanogenerators generation in the realm of wind energy, offering valuable insights for researchers and scholars in the field.

Modelling and simulation of self powered triboelectric nano generator sensor for heart beat monitoring

The triboelectric generators works on the principle of voltage produced by charge accumulation as a result of friction between between heterogenous materials. Self powered sensors is the most needed development in medical industry. Biosensors are power supply dependant.The power supply need for biosensors are catered by using mechanical energy harvesting Triboelectric Nano generators (TENGs) working on mechanical energy harvesting method is applied for developing biosensors. TENGs work on the principle, of producing charges carriers by enabling friction between two distinct materials. The generated electric energy acts as a reservoir to power the device. In bioimplantable sensors, power supply systems replacement is complex, as it needs a surgical intervention. Hence heartbeat energy is harvested for the powering pacemakers. Simulation and modelling of contact separation mode based TENGs with Spice (Simulation Program with Integrated Circuit Emphasis) software is discussed in this paper. The signal generation of the TENGs has been simulated by SPICE and analytical samplings have been carried out for the circuit analysis. Recently invented heart rate monitors are not suitable for daily usage. Hence TENGs are identified as cost effective biosensors with unique features such as light weight and high sensitivity.

The Effect of Surface Texture on Teflon as Electrification Layer of 360° Lateral-Sliding Mode Triboelectric Generator

Harvesting neglected mechanical energy from daily activities and converting it into electrical energy is a crucial start towards clean, low-cost, and sustainable energy. In this work, we report a development of a Teflon-based rotating triboelectric generator (TEG) and its relationship with rotational speed. The texture on Teflon was modified by uni-directionally rubbing the sandpaper with three different grit numbers; 500, 1000, and 1500 respectively, 50 times each. The surface roughness of the Teflon was measured using Mitutoyo Surface Roughness Machine SJ-310 before and after undergoing the 360° lateral sliding mode TEG test. The highest surface roughness was from 500 grit sandpaper, forming a Ra of 1.550 µm. Moreover, this surface of Teflon generated the highest output voltage of 25.3 mV at 1500 rpm with a calculated power density of 0.37 mW/m2. This simple technique gives an overview of how the surface texture may improve the electrical output of TEG by integrating the electrification contact area of TEG.

Bidirectional electron transfer in Triboelectrification caused by friction-induced change in surface electronic structure

Triboelectrification (TE) plays fundamental roles in a wide range of industrial and scientific fields but its charge transfer mechanisms still remains elusive. It has been widely believed that the electron transfer in TE between two homogeneous surfaces should be always unidirectional. But we found here that the electron transfer during friction process will change its direction as the position of the contact point on the friction surface changes, indicating that bidirectional electron transfer occurs between the contacting surfaces. The experiments further show that the electron transfer direction at any given contact position on the friction surface keeps unchanged over time during the whole friction process if the relative sliding direction keeps unchanged, and when the sliding direction is reversed, the electron transfer direction at a given contact position will also be reversed if the friction surface is crystalline. To explain the observed non-unidirectional electron transfer, a theoretical model for the electron transfer in TE has been proposed, assuming that the changes in the electron transfer direction can be attributed to the changes in the surface work function caused by the friction-induced tangential deformation on the friction surface. The theory has further been validated by the first principles calculations about the influence of the tangential deformation on the surface electronic structure. The present work may offer a new perspective for understanding the charge transfer mechanism in TE and may provide potential applications in numerous fields involving TE such as triboelectric generator, petrochemical industry, power electronics and textile industry.