Double-row tapered roller bearings (DTRBs) are widely used in wind turbines because of their high load-bearing capacity and durability. However, wind turbines typically operate in harsh environments, subjecting bearings to complex working conditions, which significantly increases the difficulty of operational status monitoring. Traditional monitoring methods rely on external power sources and complex sensor networks, which make them susceptible to environmental interference, and complicated to maintain. This paper presents an innovative, integrated symmetrical single-electrode triboelectric double-row tapered roller bearing (SST-DTRB) by incorporating a triboelectric nanogenerator (TENG) with DTRB. This scheme converts the frictional energy generated during bearing operation into electrical output, producing signals that enable simultaneous sensing of both ends of DTRB. Experimental results demonstrate that this monitoring scheme exhibits high sensitivity, stability, and reliability, with excellent robustness in material selection and design gap, and is capable of long-term operation without external power sources. The effectiveness and self-sensing capability of SST-DTRB under variable speeds are validated using a wind turbine test bench. High-accuracy bearing fault diagnosis under multiple conditions is achieved based on time-frequency transformation and deep residual neural networks. The proposed SST-DTRB provides in situ self-powered sensing capability for wind turbines and offers new insights in the development of intelligent sensing systems.

Tribovoltaic nanogenerator (TVNG), which manifests distinct advantages of direct-current output characteristics and remarkable energy utilization efficiency, is an emerging energy technology relying on the coupling of semiconductor and contact electrification. Dynamic semiconductor interface is the key to TVNGs, as its performance and functionality largely depend on the design and optimization of interface. Hence, with the booming development of TVNGs, it is of great significance to timely update the fundamental understanding of its interface design, which is currently lacking. In this review, the frontier advances on interface design for TVNGs are elaborately outlined for the first time. First, the underlying mechanisms of tribovoltaic effect at the interface are elaborated, as well as some governing equations and key interface design concepts. Subsequently, diverse strategies for advanced interface design are highlighted, including modulating interfacial charge dynamics, multi-energy coupling, reducing interface wear loss, and extending flexible/wearable application. At last, some assumptions about the future direction and prospects of advanced interface design in efficient, multifunctional TVNGs are presented.

In recent years, the advent of the smart era has confronted a novel "energy crisis"-the challenge of distributed energy provision, necessitating an imperative for clean energy development. Encompassing 71% of the Earth's surface, water stands as the predominant conduit for energy transfer on our planet, effectively harnessing a fraction thereof to fulfill global energy demands. Modern hydropower technology primarily harnesses concentrated low-entropy water energy. However, the majority of natural water energy is widely dispersed in the environment as high-entropy distributed water energy, encompassing raindrop energy, stream energy, wave energy, evaporation energy, and other small-scale forms of water energy. While these energies are readily available, their collection poses significant challenges. Consequently, researchers initiated investigations into high-entropy water energy harvesting technology based on the electrodynamic effect, triboelectric effect, water volt effect, and other related phenomena. The present paper provides a comprehensive review of high-entropy water energy harvesting technologies, encompassing their underlying mechanisms, optimization strategies, and diverse applications. The current bottlenecks of these technologies are comprehensively analyzed, and their future development direction is prospectively discussed, thereby providing valuable guidance for future research on high-entropy water energy collection technology.

Nowadays, the liquid-solid triboelectric nanogenerator (L-S TENG) has gained much attention among researchers because of its ability to be a part of self-powering technology by harvesting ultra-low-frequency vibration in the environment. The L-S TENG works with the principle of contact electrification (CE) and electrostatic induction, in which CE takes place between the solid and liquid. The exact mechanism behind the CE at the L-S interface is still a debatable topic because many physical parameters of both solid and liquid triboelectric layers contribute to this process. In the L-S TENG device, water or solvents are commonly used as liquid triboelectric layers, for which their wettability over the solid triboelectric layer plays a significant role. Hence, this review is extensively focused on the influence of the wettability of solid surfaces on the CE and the corresponding impact on the output performance of L-S TENGs. The present review starts with introducing the L-S TENG, a mechanism that contributes to CE at the L-S interface, the significance of hydrophobic materials/surfaces in TENG devices, and their fabrication methods. Further, the impact of the contact angle over the electron/ion transfer over various surfaces has been extensively analyzed. Finally, the challenges and future prospects of the fabrication and utilization of superhydrophobic surfaces in the context of L-S TENGs have been included. This review serves as a foundation for future research aimed at optimizing the L-S TENG performance and inspiring new approaches in material design and multifunctional energy-harvesting systems.

Wetting behaviors can significantly affect the transport of energy and signal (E&S) through vapor, solid, and liquid interfaces, which has prompted increased interest in interfacial science and technology. E&S transmission can be achieved using electricity, light, and heat, which often accompany and interact with each other. Over the past decade, their distinctive transport phenomena during wetting processes have made significant contributions to various domains. However, few studies have analyzed the intricate relationship between wetting behavior and E&S transport. This review summarizes and discusses the mechanisms of electrical, light, and heat transmission at wetting interfaces to elucidate their respective scientific issues, technical characteristics, challenges, commonalities, and potential for technological convergence. The materials, structures, and devices involved in E&S transportation are also analyzed. Particularly, harnessing synergistic advantages in practical applications and constructing advanced, multifunctional, and highly efficient smart systems based on wetted interfaces is the aim to provide strategies.

Converting dispersed mechanical energy into electrical energy can effectively improve the global energy shortage problem. The dispersed mechanical energy generated by liquid flow has a good application prospect as one of the most widely used renewable energy sources. Solid-liquid triboelectric nanogenerator (S-L TENG) is an inspiring device that can convert dispersed mechanical energy of liquids into electrical energy. In order to promote the design and applications of S-L TENG, it is of vital importance to understand the underlying mechanisms of energy conversion and electrical energy output affecters. The current research mainly focuses on the selection of materials, structural characteristics, the liquid droplet type, and the working environment parameters, so as to obtain different power output and meet the power supply needs of diversified scenarios. There are also studies to construct a theoretical model of S-L TENG potential distribution mechanism through COMSOL software, as well as to obtain the adsorption status of different kinds of ions with functional groups on the surface of friction power generation layer through molecular dynamics simulation. In this review, we summarize the main factors affecting the power output from four perspectives: working environment, friction power generation layer, conductive part, and substrate shape. Also summarized are the latest applications of S-L TENG in energy capture, wearable devices, and medical applications. Ultimately, this review suggests the research directions that S-L TENG should focus on in the future to enhance electrical energy output, as well as to expand the diversity of application scenarios.

Contact-induced electrification, commonly referred to as triboelectrification, is the subject of extensive investigation at liquid-solid interfaces due to its wide range of applications in electrochemistry, energy harvesting, and sensors. This study examines the triboelectric between an ionic liquid and 2D MoS2 under light illumination. Notably, when a liquid droplet slides across the MoS2 surface, an increase in the generated current and voltage is observed in the forward direction, while a decrease is observed in the reverse direction. This suggests a memory-like tribo-phototronic effect between ionic liquid and 2D MoS2 . The underlying mechanism behind this tribo-phototronic synaptic plasticity is proposed to be ion adsorption/desorption processes resulting from pseudocapacitive deionization/ionization at the liquid-MoS2  interface. This explanation is supported by the equivalent electrical circuit modeling, contact angle measurements, and electronic band diagrams. Furthermore, the influence of various factors such as velocity, step size, light wavelength and intensity, ion concentration, and bias voltage is thoroughly investigated. The artificial synaptic plasticity arising from this phenomenon exhibits significant synaptic features, including potentiation/inhibition, paired-pulse facilitation/depression, and short-term memory (STM) to long-term memory (LTM) transition. This research opens up promising avenues for the development of synaptic memory systems and intelligent sensing applications based on liquid-solid interfaces.

Tribovoltaic nanogenerators (TVNGs) have the characteristics of high current density, low matched impedance and continuous output, which is expected to solve the problem of power supply for small electronic devices. However, wear occurrence in friction interface will seriously reduce the performance of TVNGs as well as lifetime. Here, we employ MXene solution as lubricate to improve output current density and lifetime of TVNG simultaneously, where a high value of 754 mA m-2 accompanied with a record durability of 90,000 cycles were achieved. By comparing multiple liquid lubricates with different polarity, we show that conductive polar liquid with MXene as additive plays a crucial role in enhancing the electrical output performance and durability of TVNG. Moreover, the universality of MXene solution is well demonstrated in various TVNGs with Cu and P-type Si, and Cu and N-GaAs as material pairs. This work may guide and accelerates the practical application of TVNG in future.

Contact electrification (CE) occurs naturally at all interfaces between solids and solids, solids and liquids, solids and gasses, and so forth. It has been extensively studied for decades. While CE at a solid-solid interface has been demonstrated to be primarily caused by electron transfer, the underlying mechanism of CE at a liquid-solid interface remains controversial. In this paper, the CE process between polyethylene terephthalate (PET) and different inorganic solutions at different temperatures is studied to investigate the charge transfer mechanism. The observed temperature-CE charge relationship falls into two categories, that is, the general case and the special case. In the general case, the CE charge first increases negatively and then positively with the temperature. The CE charge increasing negatively could result from enhanced electron transfer at the interface, while the CE charge increasing positively may be caused by increasing adsorption of cations, which neutralize the negative charges on the PET surface. In contrast, the CE charge first increases positively and then negatively with the temperature in the special case. The CE charge increasing positively could be attributed to more cations being attracted to the negatively charged PET surface, while the charge increasing negatively may be caused by more anions being attracted to the PET due to enhanced cation adsorption. Supported by the surface charge and dynamic charge transfer at different PET-solution interfaces and solution temperatures, our study provides a plausible interpretation of the temperature-dependent CE at the polymer-liquid interfaces.