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Solid‐liquid triboelectric nanogenerators (SL‐TENGs) are a new technology that combines contact electrification (CE) and electrostatic induction to collect clean energy stored in natural water. Considering their unique advantages of high energy density, wide selection of materials and being suitable for large‐scale promotion, they have attracted more and more attention in recent years, and numerous studies have shown their great potential in various applications. Many critical applications of SL‐TENGs inevitably involve sustained and stable high electrical output. To achieve stable output performance and long cycle life in these applications, the adaptability of SL‐TENGs to material selection, structural design, and working environment is necessary. Therefore, the construction of SL‐TENGs matching different applications has become a critical research direction in TENGs. This review provides a historical summary of the development of SL‐TENGs in the past few years and analyzes the key factors affecting their electrical output performance. The exciting achievements of different constructions of SL‐TENGs for practical applications is also demonstrated such as energy harvesting, self‐powered sensing, and self‐powered cathodic protection. Finally, the development prospects of SL‐TENGs and the significant challenges for their further development is discussed. [ABSTRACT FROM AUTHOR]

As a new sustainable energy utilization way, triboelectric nanogenerators (TENGs) have attracted increasing attention in recent years. Herein, a new TiO2 nanotube coating based TENG (TNC‐TENG) with corrosion resistance and self‐healable electrical output properties for energy harvesting is developed. The inorganic coating is prepared by anodic oxidation (AO) and fluoridation with titanium. The TiO2 nanotube coating based TENG has a current output of 17.4 µA and a voltage output of 220 V. The fluorinated titanium oxide nanotubes coating has good hydrophobicity. When the fluorine composition on the coating surface is damaged by plasma, the triboelectric current decreases to 7 µA. The self‐healable hydrophobicity and electrical output property are achieved by transferring loaded perfluorosilane to the damaged surface. In addition, the electric energy generated in the triboelectrification can improve the anticorrosion performance for metal matrix by cathodic protection. Based on the corrosion resistance and self‐healing properties, the TNC‐TENG has potential applications in the field of energy collection, energy supply, and corrosion protection. [ABSTRACT FROM AUTHOR]

In the field of blue energy harvesting, solid-liquid triboelectric nanogenerators (SL-TENG) show significant potential. However, their low output performance in energy applications is limited due to the relatively small contact area and slow separation speed during the friction process. To overcome these limitations, we develop a pneumatic solid-liquid triboelectric nanogenerator (PSL-TENG) with ultrahigh output performance based on pneumatic solid-liquid triboelectrification and electrostatic breakdown. The pneumatic design effectively increases the solid-liquid interface area and the solid-liquid contact and separation rate, which can enhance solid-liquid triboelectrification effect. The synergistic design of the horn and the bent pipe can converge positively charged mist into large droplets, which can enhance electrostatic breakdown effect. This innovative design approach has achieved outstanding output performance, with a peak instantaneous voltage of 6436 V and a peak instantaneous current of 3.05 mA. This exceptional output performance is sufficient to directly power 3000 LED lights or a 55 W commercial lamp. These research achievements provide new insights for SL-TENG in energy harvesting, as significant output can be generated by collecting the inherent charges of liquids themselves. [Display omitted] • A new solid-liquid triboelectric nanogenerator based on pneumatic principles. • The peak voltage of the PSL-TENG can reach 6436 V, and the peak current can reach 3.05 mA. • The PSL-TENG can directly power a 55 W commercial lamp or illuminate 3000 LED lights. • Proposed a new mechanism that can achieve such a large output by relying on the charge of the liquid itself. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerator (TENG) is a new type of device that can convert mechanical energy in the environment into electrical energy. Since its wide range of energy sources, high energy conversion efficiency and wide application range, it has become a hot spot in the energy field. However, the shortcomings of the high internal resistance, the low output current and power density have seriously affected the further applications of TENGs. This review is aimed to introduce the recent advanced methods and applications of controlling the interface contact electrification of TENGs, and identify and discuss the key issues that deserve additional studies. This paper delineates the advanced methods and applications of enhancing the electrical output of TENG and looks forward to the application prospects of TENG in other fields. [ABSTRACT FROM AUTHOR]

Online measurement of liquid flow rate in high-speed gas-liquid two-phase flow remains a considerable challenge for practical engineering applications. Owing to the non-linear and non-smooth characteristics, it is not easy to achieve effective measurement of liquid-phase flow without separation of gas-liquid two-phase using conventional methods. An alternative, the solid/liquid-based triboelectric nanogenerator, has a great potential for self-powered sensing of liquid states. Herein, a ring-shaped single-electrode triboelectric nanogenerator (RSE-TENG) by combining contact electrification (CE) and electrostatic induction is designed for energy harvesting and parameter monitoring of gas-liquid two-phase flow. The RSE-TENG can achieve stable short-circuit current and open-circuit voltage peaks of 24 µA and 344 V, respectively. And a self-powered real-time liquid-phase flow monitoring system with a measurement range of 4–20 mL/min for gas-liquid two-phase flow is developed based on the RSE-TENG. It has the advantages of simple structure, low cost, fast response time, and can achieve effective non-contact measurement of liquid-phase flow without separation of gas-liquid two-phase. This measurement method based on the electric signal of triboelectricity at the solid-liquid interface can provide guidance and reference for the related research on fluid mechanics. [Display omitted] • A systematic study of the triboelectrification behavior of the high-speed gas-liquid two-phase flow with a solid surface was investigated. • Highlighting the feasibility of using the triboelectricity for parameters monitoring of the gas-liquid two-phase flow system. • Harvesting energy from high-speed gas-liquid two-phase flow in the transportation pipelines. • Proposing a self-powered liquid-phase flow monitoring system with a measurement range of 4-20 mL/min of gas-liquid two-phase flow. [ABSTRACT FROM AUTHOR]

Self-powered triboelectric nanosensor (TENS) has attracted increasing attention in recent years due to its independent and sustainable operations without external power source. In this paper, we demonstrate a newly designed fully packaged liquid-solid TENS based on the friction between polytetrafluoroethylene (PTFE) filtration membranes and water. The dependencies of output performance of water-based TENS on the water-to-cylinder volume ratio, vibration frequency and amplitude using fluid mechanics analysis are demonstrated. By modifying PTFE filtration membrane with dopamine, this TENS can be used as dopamine sensor with high selectivity and sensitivity (detection limit of 0.1 µM, a linear range from 10 µM to 1 mM). Besides, by mixing with organics (such as ethanol) to decrease the water polarity, this TENS can be used as a sensor for the detection of ethanol concentration in water with fast response at room temperature. Compared with the existing solid-solid triboelectrication based TENS, this fully packaged liquid-solid triboelectrication based TENS is portable, easily fabricated, and has potential application for detecting toxic pollutants in water with higher sensitivity. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) with sliding-mode have developed rapidly in the field of energy harvesting and sensing. However, its surface wear and low electric output performance usually limit its applicability. Herein, a mixture of hexadecane with onion-like carbon (OLC) lubricant is added to the interface between polytetrafluoroethylene (PTFE) film and steel to enhance the triboelectrical and tribological performance. During dry friction, the friction pair is severely worn and the current output decreases gradually with the transfer of a large amount of PTFE debris in a short period. The introduction of hexadecane partly resolves the problems such as friction and wear with the reduction in the transfer of PTFE material. However, the current output decreases gradually during the friction process because there is still some slight material transfer in the interface. The electrical output of TENG is further enhanced with the addition of OLC, and its tribological properties are comparable or better than oil-based TENG. The short-circuit currents (I sc) of the oil-based TENG and the oil-OLC-based TENG are 1.5 times and 5 times that of the TENG in the dry friction state, respectively. Also, the coefficient of friction (COF) of oil-OLC-based TENG is reduced by about 75.3% compared with dry friction state. The oil-OLC-based lubricant reduces the transfer film formation, increases the effective contact area, and squeezes the air at the interface. Also, part of the OLC rolls between the two friction layers, forming a "micro-bearing", further reducing the generation of transfer film. This study provides a novel way to improve the output efficiency and prolong the service life of TENG. [Display omitted] • Hexadecane-Onion-like carbon (OLC) lubricant further increases the triboelectricity. • The wear resistance of TENG is further improved by using hexadecane-OLC. • OLC doped hexadecane further inhibits material transfer during friction. • Hexadecane-OLC lubrication greatly extends the service life of TENG. [ABSTRACT FROM AUTHOR]

In this paper, a new type of ice - based triboelectric nanogenerator (ICE-TENG) has been fabricated to harvest energy in cold weather. Ice is a preferred material for designing TENGs in cold winter, alpine or snowy mountain regions because of its cleanness, environmental protection, abundant reserves, low friction, and self-healing properties. The short-circuit current and voltage can achieve 2.4 µA and 48 V with 4 mm thickness of ice layer, 30 N loadings, and 5 Hz contact frequency, which can be useful in some practical applications such as lighting LEDs and charging capacitors. The ICE-TENG possesses excellent stability and can reach an output power of 35 µW under 20 MΩ loading resistance. The coefficient of friction between ice and other friction pairs is negligible, and it can even become super-slippery with the coefficient of friction below 0.008. Thus, the wear of the friction pairs is small, which can help TENG to have a long working life. Besides, due to the rapid phase change of ice, the ICE-TENG exhibits a commendable self-healing ability and maintains the original output performance after several damage and repair processes. To simulate the practical applications, a single electrode ICE-TENG driven by walking has been designed for harvesting energy on the ice surface. Because of the difference in electric output before and after the ice fragmentation, the ICE-TENGs are designed to construct a warning system to remind the danger when the ice surface suddenly shatters. Moreover, such ICE-TENGs are capable of lighting "ICE" LEDs and powering an electric watch with footsteps. This illustrates a promising potential in self-powered systems such as danger warning, charge shortage, and energy harvesting. The ice is one of the most common natural resources with its abundant reserves and wide coverage on the earth. To relieve the energy crisis in cold environment, we fabricated the ICE-TENGs by combining ice layers with the polymer films. The ice self-powered devices could convert mechanical energy into electric energy during people's motion on the ice surface. Due to the significant change after the ice layer breaks up, a warning system was established to detect the real-time danger and raise the alarm, which could ensure people's safe activities on the ice. The super-slippery state of the ice surface also endowed the long service life of the ICE-TENGs in energy harvesting. Therefore, the ICE-TENGs not only provides a strategy to utilize the ice layer to harvest energy, but also shows great prospects for practical applications in danger warning and self-powered systems in cold environment. [Display omitted] • ICE-TENGs are fabricated for energy harvesting in cold environment. • The super-slippery property of the ICE-TENGs ensures the excellent wear resistance and long life of TENG. • The ICE-TENGs have multiple reversible self-healing properties during the phase transition process. • ICE-TENGs can be utilized to fabricate a warning system to protect people's safe on the ice surface. [ABSTRACT FROM AUTHOR]

Peeling the adhesion interface is a common contact-separation process at the interface, but harvesting and effectively regulating the mechanical energy remains a challenge. Herein, we designed a new protocol triboelectric nanogenerator based on interfacial adhesion-peeling behavior (AP-TENG). The basic relationship between adhesion force and peeling current reveals that rapid jumping out of contact of the adhesion interface enhanced peeling electrification. Also, the design of the grid structure allows for rapid separation of the adhesion interface. The current of AP-TENG during peeling is approximately four times larger than that of the flat surface, allowing for the monitoring of interface fracture. In the rolling mode, AP-TENG can peel the adhesive tape from the surface of the substrate at a very small angle, resulting in a shocking current of up to about 15 μA. The present results confirm the role of adhesion in triboelectricity and expand the potential applications of adhesive materials for energy harvesting. [Display omitted] The peeling electrification of adhesive interface is a special case of triboelectrification, which is strongly affected by the peeling condition (contact interface continuity, velocity, angle, etc.) and the energy dissipation during the separation process of adhesive interface. This work successfully converted the mechanical energy into electrical energy during peeling process, and explored the mechanism and influencing factors of peeling electrification at the adhesion interface. • Peeling electrification is a special case of contact electrification. • Peeling electrification is driven by the energy dissipation behavior of adhesive tape. • The adhesion-peeling triboelectric nanogenerators successfully convert the mechanical energy into electrical energy. • Adhesion failure detection is achieved by energy harvesting in peeling-electrification mode. [ABSTRACT FROM AUTHOR]

A new type of gas-solid two-phase flow-based triboelectric nanogenerator (WS-TENG) is fabricated for collecting triboelectric energy in wind-blown sand environment, producing direct current output, and harvesting kinetic energy of continuous wind-blown sand flow. A single-electrode mode WS-TENG is designed with polytetrafluoroethylene (PTFE) as friction layer and used to investigate triboelectrification between wind-blown sand flow and friction layer surface using sediment-air injection method. Results showed that both short-circuit current (I sc) and output voltage (V o) are direct current modes that increase with increasing impact angle and sand feed rate and reach 2 µA and 55 V, respectively, at a flow velocity of 18 m·s−1 to charge capacitor and light up five LEDs as a wind-blown sand flow kinetic energy collector. Moreover, output performance of WS-TENG can be improved further by pre-charging the floating sand using a PTFE pipe due to coupling of electrostatic induction and triboelectrification effect. WS-TENG was also applied as a self-powered sensor for aeolian sand transport rate in harsh sandstorm environment, thereby indicating its potential application for tracking the evolution of aeolian desertification and developing practical sensing applications of gas-solid two-phase flow-based TENG. [Display omitted] • A novel wind-blown sand flow-based triboelectric nanogenerator (WS-TENG) has been proposed and developed. • The WS-TENG can efficiently harvest the kinetic energy of wind-blown sand flow in a sandstorm environment. • A self-powered active sand transport rate sensor based on precharged WS-TENG has been developed. • The gas-solid two-phase flow as frictional media has been introduced into the TENG filed. [ABSTRACT FROM AUTHOR]

Moisture in environment can severely decrease the output of the solid-solid triboelectric nanogenerators (TENGs) which usually hinders their further practical applications. To solve this problem, in this paper we fabricated a new type of biofilm materials based TENG, which can work stably in high humidity environment with high output performance by forming hydrogen bond with water molecules. In high humidity environment the hydroxyl-rich biomaterials, such as starch molecules, and water molecules could form hydrogen bonds spontaneously to fix water molecules on the surface, which allows water molecules to participate in triboelectric charging as a more electropositive material to obtain a higher output of TENG. Different from the traditional polymer materials based TENGs, the output of the starch films based TENG increases with the increase of the environmental humidity. The output current and voltage could increase from 6.2 μA to 110 V to 16.6 μA and 330 V with the ambient humidity increasing from 15% to 95%, respectively, which is about 12 times larger than that of the traditional nylon-11 based TENG in the humidity of 95%. It is an important supplement of TENG family and highly expand application scopes for energy harvesting and self-powered sensors in high humidity environment, especially in cloudy, foggy days or under water and sweat conditions. A new kind of biofilm material based triboelectric nanogenerator (TENG) with high output performance is constructed for energy harvesting in high humidity environment, solving the output reduction of solid-solid TENG with the increase of environmental humidity. This type of TENG has promising potential applications in energy harvesting, self-powered electronic devices early warning devices in fog, ocean, and other high humidity environment. Image 1 • This new type of triboelectric nanogenerator can work stably in high humidity environment with high output performance. • This TENG is fabricated with an environment friendly and biodegradable hydroxyl-rich material without any specific treatment. • Biofilm materials based TENGs have universal characteristics of high output under high humidity. [ABSTRACT FROM AUTHOR]

Solid–liquid contact triboelectrification has been a hot and important topic due to its severe electrostatic hazards in the petroleum industry and its positive potential application in energy harvesting. Here, the influence of surface structure, composition, and interfacial wettability on the solid–liquid triboelectrification basing on the friction of polypropylene (PP) films and deionized water is systematically studied. PP films with different nanowire structures are prepared by a hot pressing method with varied anodic aluminum oxide as templates. The PP films are surface functionalized with three different functional groups by a surface self‐assembly technology. The results show that compared with the surface structure, the solid–liquid triboelectrification is more sensitive to the surface components. While from the macroscopic view the interfacial wettability plays a dominant role in its electrical output, with the failure of the hydrophobic surface of the PP film, the triboelectrical output continues to deteriorate. Moreover, the increase or decrease of solid–liquid triboelectrification can be achieved by controlling the structure or composition. This study demonstrates the possibility of adjusting the solid–liquid contact electrification in a controllable manner and provides a basis for the utilization or the prevention of solid–liquid friction charges. [ABSTRACT FROM AUTHOR]

• High-humidity invalidity of traditional cathodic protection needs to be further improved. • A novel wind-driven and humidity-resistant TENG is designed to constitute the self-powered CP system. • High-humidity wind energy collection and in situ cathodic protection are achieved. • The protected metal gets an obvious open-circuit potential drop, which is 590 mV. The triboelectric nanogenerator (TENG) is a novel energy harvesting strategy to convert various types of mechanical energy into electrical energy through the synergistic effect of triboelectrification and electrostatic induction. A hydrophobic polytetrafluoroethylene (PTFE) flexible film was introduced to establish a wind-driven TENG as the power supply for a self-powered cathodic protection (CP) system. The PTFE flexible film was used as the friction layer with polyvinyl alcohol (PVA) film to generate charges. The developed triboelectric charges were transferred to the cathodic protection system. The PTFE-based flexible TENG exhibits enhanced output performance with an optimized short current of 29.72 μA, an output voltage of 695.18 V, and an optimized power of 1.74 mW at 95% RH (Relative Humidity). Besides, through the external connection to the protected metal, the PTFE-based flexible TENG established the power supply of the self-powered anticorrosion system. In the electrochemical measurements, an apparent open-circuit potential drop (OCP) of 590 mV was achieved for the carbon steel connected with the wind-driven TENG, and the charge transfer resistance was also significantly reduced. Due to the high performance of the flexible TENG under high humidity, this smart self-powered system could effectively collect wind energy in the marine environment and prevent metal corrosion in marine facilities by converting wind power. The self-powered cathodic protection system provided a novel and efficient strategy for harvesting and converting abundant wind energy in high humidity condition, by which the in situ corrosion protection of metals in the marine environment was achieved.Prime Novelty Statement: Wind energy collection and corrosion prevention from high humidity environments basing on flexible TENG. [Display omitted] [ABSTRACT FROM AUTHOR]

A new type of array combination for liquid-solid triboelectric nanogenerators is constructed by using polytetrafluoroethylene ultrafiltration membrane as the friction layer with water to collect wave energy to self-power the cathodic protection system in marine environment. The dual liquid-solid triboelectric nanogenerator array shows the output performance with a short current circuit of 2.68 μA and output voltage of 105 V. Meanwhile, a self-powered corrosion protection system with liquid-solid triboelectric nanogenerators array as the power supply is achieved for A3 carbon steel in 3.5 wt% NaCl solution. The electrochemical measurements results show that compared with the bare carbon steel, the open circuit potential drop of the carbon steel coupled with the liquid-solid triboelectric nanogenerators is about 330 mV. Compared with photocathodic protection and other new energy-based methods, the solid-liquid triboelectric nanogenerator could realize all-weather protection of metals by utilizing natural energy and through parallel or series circuit design, it could be used to achieve more efficient cathodic protection for metal materials. The intelligent self-powered system possesses great potential in the area of all-weather cathodic protection and power supply by utilizing liquid-solid friction energy for the ships, buoys, and marine equipments in ocean conditions. Prime Novelty Statement: All-weather ocean energy collection and corrosion prevention basing on solid-liquid TENGs array. Image 1 • Dark invalidity of photogenerated cathodic protection needs to be further improved. • A novel dual solid-liquid TENGs array is constructed to achieve higher output. • All-weather wave energy collection and cathodic protection are achieved. • The protected metal gets an obvious open-circuit potential drop, which is 330 mV. [ABSTRACT FROM AUTHOR]