Xue Liu

Wind energy is one of the most abundant and sustainable renewable energy resources. However, its efficient utilization remains challenging because of fluctuating wind speeds and multidirectional airflow. In this work, we develop a dual-rotor hybrid triboelectric–electromagnetic energy harvester (H-TENG) featuring flexible multiwalled carbon nanotube/poly(dimethylsiloxane) (MWCNTs/PDMS) composite electrodes to improve wind energy harvesting efficiency. The effects of electrode materials and rotor configurations on the electrical output of the device are systematically investigated. Compared with conventional copper electrodes, the flexible MWCNTs/PDMS composite electrodes increase the peak output power of the triboelectric unit by 46.1% at a wind speed of 6 m s⁻¹, while the dual-rotor configuration further enhances the peak output power by up to approximately 195.6% relative to the single-rotor design. To overcome the limited, short-circuit current output of the triboelectric generator, an electromagnetic generator is integrated into the hybrid system. The optimized device delivers a maximum output open-circuit voltage of 1212.34 V from the TENG and a maximum short-circuit current of 13.64 mA from the EMG. The harvested energy is sufficient to continuously power a digital watch and 240 light-emitting diodes (LEDs). This work provides an effective material–structure synergistic strategy for high-performance hybrid wind energy harvesters and offers a promising approach for harvesting low-speed and multidirectional wind energy.

Cellulose regeneration from ionic liquids (ILs) proceeds through a nonequilibrium pathway in which solvent exchange, intermolecular interactions, and structural ordering are strongly coupled, yet the causal relationships among these processes remain incompletely understood. Here, we investigate how coagulant‐driven solvent exchange and coagulant‐specific intermolecular interactions jointly influence structural evolution during cellulose regeneration. By integrating time‐resolved polarized light microscopy, FT‐IR/2D correlation spectroscopy, and SAXS measurements over 0–60 min with molecular dynamics (MD) simulations, the regeneration process is examined across molecular‐to‐fiber scales. The combined results suggest that solvent exchange is associated with changes in intermolecular interactions and chain organization, accompanied by hydrogen‐bond reorganization. At the molecular level, a disorder‐to‐order transition in glucopyranose ring orientation is identified, suggesting a possible molecular link between interaction evolution and mesoscale structural development. The combined experimental observations suggest different regeneration trajectories in water and ethanol, associated with coupled differences in solvent‐exchange kinetics and intermolecular interactions. These results provide insight into how solvent exchange and intermolecular interactions jointly influence nonequilibrium ordering during regeneration, offering a multiscale framework for understanding and controlling processing–structure relationships in regenerated cellulose and related polymer systems.

Wind energy, an abundant renewable resource, remains difficult to harness efficiently due to fluctuating speeds and unpredictable directions. In this work, we present a wind bell-inspired triboelectric nanogenerator (WB-TENG) designed for omnidirectional, variable-speed wind harvesting, utilizing layered triboelectric polymers such as polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), and polyamide (PA) to enhance energy capture performance. The developed device demonstrates the ability to generate electrical output even under extremely low wind speeds as low as 0.5 m/s. Additionally, it successfully captures wind energy from all directions within a full 360° range. Through structural optimization, the WB-TENG achieves a peak output voltage of 25.1 V and a maximum power of 3.5 μW, representing substantial improvements of 170% and 1232%, respectively, over the performance of our previous prototype. To verify its practical capability, the optimized WB-TENG is employed to power several electronic devices, including a digital watch and 50 commercial LEDs, confirming its potential for real-world energy harvesting applications. This work presents a novel and effective strategy for harnessing wind energy under dynamic environmental conditions, offering a sustainable approach for decentralized energy collection in low-speed and omnidirectional wind settings.

Multi-stimulus responsive materials have attracted significant attention due to their ability to respond dynamically to multiple external stimuli, including light, temperature, and chemical signals. Achieving both rapid response times and precise selectivity is essential for advancing the functionality of such materials. In this study, five polyoxometalate-based viologen ionic liquids (ILs) were synthesized through ion exchange between H₃PMo₁₂O₄₀ and viologen ILs with varying substituents. These ILs demonstrated multi-stimulus responses to light and ammonia gas. Under Xe lamp irradiation, all ILs exhibited prominent photochromism, with C₁₂–PMo₁₂ undergoing a rapid change from light yellow to light green within just 5 seconds. Exposure to an H₂O₂ atmosphere for 3 hours resulted in the complete decolorization of C₁₂–PMo₁₂. Remarkably, after five cycles of coloring and decoloring, its absorbance remained virtually unchanged, highlighting its excellent reversibility and stability. Additionally, as the alkyl chain length of the viologen-based cation increased, the coloring rate accelerated, and the color contrast enhanced, likely due to the suppression of viologen radical quenching by longer carbon chains. These ILs also exhibited gas-chromic behavior in the presence of ammonia, showing high detection selectivity. Furthermore, the materials were successfully applied in inkless erasable printing and ultraviolet detection. The C₁₂–PMo₁₂-based carbon paper displayed clear and readable prints in only 10 seconds and could be bleached in an H₂O₂ atmosphere within 1.5 hours. These findings demonstrate that the synthesized ILs possess versatile multi-stimulus responsive properties, making them highly promising for applications in inkless printing, ultraviolet detection, and amine vapor sensing.

A revised version of the Poon and Shin (PS) model, incorporating the effects of the interphase, is introduced to predict the dielectric permittivity of polymer nanocomposites reinforced with spherical nanoparticles. In this modified approach, both the spherical nanoparticle and its surrounding interphase region are treated as an equivalent nanoparticle, modeled as a core–shell structure. This assumption enables a more accurate representation of the composite, where the polymer matrix and the equivalent nanoparticles form a homogeneous mixture. The process of calculating the dielectric permittivity of the composite occurs in two distinct steps. Initially, the dielectric permittivity of the equivalent particle—comprising both the nanoparticle core and its interphase—is computed. Subsequently, the overall dielectric permittivity of the composite material is determined, considering the properties of the polymer substrate and the equivalent nanoparticles, all within the framework of the modified PS model. To verify the validity of the proposed model, experimental data are compared against the predicted values, showing a high level of agreement when the interphase characteristics are appropriately incorporated. Additionally, the influence of various factors, including the properties of the spherical nanoparticles, the interphase, and the polymer matrix, on the dielectric performance of the nanocomposite is thoroughly investigated. This enhanced PS model offers a valuable theoretical framework for designing polymer–spherical nanoparticle composites with superior dielectric properties, paving the way for their potential application in advanced electronic and energy storage devices.

Human physical activity monitoring plays a crucial role in promoting personalized health management. In this work, inspired by an ancient Chinese belt, a belt-type wearable sensor (BWS) based on a triboelectric nanogenerator (TENG) is presented to monitor daily movements and collect the body motion mechanical energy. The developed BWS consists of a soft silicone sheet and systematically connected sensing units made from triboelectric polymer materials including polytetrafluoroethylene (PTFE) and polyamide (PA). A parameter study of the sensing units is firstly conducted to optimize the structure of BWS. The experimental studies indicate that the parameter-optimized BWS unit achieves a maximum output voltage of 47 V and a maximum current of 0.17 μA. A BWS with five sensing units is manufactured to record body movements, and it is able to distinguish different physical activities including stillness, walking, running, jumping, normal breathing, cessation of breathing, and deep breathing. In addition, the developed BWS successfully powers electronic devices including a smartphone, digital watch, and LED lights. We hope this work provides a new strategy for the development of wearable self-powered intelligent devices.