The rapid advancement of intelligent wearable electronics imposes the emergent requirement for power sources that are deformable, compliant, and stretchable. Power sources with these characteristics are difficult and challenging to achieve. The use of liquid metals as electrodes may provide a viable strategy to produce such power sources. In this work, we propose a liquid-metal-based triboelectric nanogenerator (LM-TENG) by employing Galinstan as the electrode and silicone rubber as the triboelectric and encapsulation layer. The small Young's modulus of the liquid metal ensures the electrode remains continuously conductive under deformations, stretching to a strain as large as ∼300%. The surface oxide layer of Galinstan effectively prevents the liquid Galinstan electrode from further oxidization and permeation into silicone rubber, yielding outstanding device stability. Operating in the single-electrode mode at 3 Hz, the LM-TENG with an area of 6 × 3 cm produces an open-circuit voltage of 354.5 V, transferred short-circuit charge of 123.2 nC, short-circuit current of 15.6 μA, and average power density of 8.43 mW/m, which represent outstanding performance values for TENGs. Further, the LM-TENG maintains stable performance under various deformations, such as stretching, folding, and twisting. LM-TENGs in different forms, such as bulk-shaped, bracelet-like, and textile-like, are all able to harvest mechanical energy from human walking, arm shaking, or hand patting to sustainably drive wearable electronic devices.

Loading metal guests within metal-organic frameworks (MOFs) via secondary functional groups is a promising route for introducing or enhancing MOF performance in various applications. In this work, 14 metal ions (Li, Na, K, Mg, Ca, Ba, Zn, Co, Mn, Ag, Cd, La, In, and Pb) have been successfully introduced within the MIL-121 MOF using a cost-efficient route involving free carboxylic groups on the linker. The local and long-range structure of the metal-loaded MOFs is characterized using multinuclear solid-state NMR and X-ray diffraction methods. Li/Mg/Ca-loaded MIL-121 and Ag nanoparticle-loaded MIL-121 exhibit enhanced H and CO adsorption; Ag nanoparticle-loaded MIL-121 also demonstrates remarkable catalytic activity in the reduction of 4-nitrophenol.

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Hematite is one of the most promising photoanodes for photoelectrochemical (PEC) solar water splitting. However, due to the low conduction band position for water reduction, an external bias is necessarily required with the consumption of extra power. In this work, a titanium modified hematite (Ti-FeO) photoanode-based self-powered PEC water splitting system in tandem with a rotatory disc-shaped triboelectric nanogenerator (RD-TENG) has been developed. It is a fantastic strategy to effectively drive the hematite-based PEC water splitting by using the environmental mechanical energy through a TENG. When the rotation speed is 65 rpm (water flowing rate ∼0.61 m/s), the peak current reaches to 0.12 mA under illumination contrast to that in the dark with almost zero. As for 80 rpm, the peak currents are 0.17 and 0.33 mA in the dark or under illumination, respectively, indicating the simultaneous occurrence of electrolysis and PEC water splitting. When higher than 120 rpm, the peak current in the dark is nearly equal to that under illumination, which can be attributed to the high enough peak voltage for direct electrolysis of water. Such a self-powered PEC water splitting system provides an alternative strategy that enables to convert both solar and mechanical energies into chemical energies.

Traditional triboelectric nanogenerator (TENG)-based self-powered chemicalsensing systems are demonstrated by measuring the triboelectric effect of the sensing materials altered by the external stimulus. However, the limitations of triboelectric sensing materials and instable outputs caused by ambient environment significantly restrict their practical applications. In this work, a stable and reliable self-powered chemical-sensing system is proposed by coupling triboelectric effect and chemoresistive effect. The whole system is constructed as the demo of a self-powered vehicle emission test system by connecting a vertical contact-separate mode TENG as energy harvester with a series-connection resistance-type gas sensor as exhaust detector and the parallel-connection commercial light-emitting diodes (LEDs) as alarm. The output voltage of TENG varies with the variable working states of the gas sensor and then directly reflects on the on/off status of the LEDs. The working mechanism can be ascribed to the specific output characteristics of the TENG tuned by the load resistance of the gas sensor, which is responded to the gas environment. This self-powered sensing system is not affected by working frequency and requires no external power supply, which is favorable to improve the stability and reliability for practical application.

Sn nanoparticles on nitrogen doped carbon nanofibers (Sn@NCNFs) composites have been synthesized by electrostatic spinning technique and used as the anode of sodium-ion batteries (SIBs) with the capacity of 390 mA h g−1 at 1 C for over 1000 cycles.

Although there has been rapid advancement in wearable electronics, challenges still remain in developing wearable and sustainable power sources with simple fabrication and low cost. In this work, we demonstrate a flexible coaxial fiber by fabricating a one-dimensional triboelectric nanogenerator (TENG) outside and a supercapacitor (SC) inside, which can not only harvest mechanical energy but also store energy in the all-in-one fiber. In such a coaxial fiber, carbon fiber bundles are utilized as the electrode material for the TENG as well as the active and electrode material for the SC. Meanwhile, silicone rubber serves as the separator between the SC and TENG, as the triboelectric material for the TENG, and as the encapsulation material for the whole fiber as well. Moreover, both SC and TENG exhibit good performance and stability, which ensures their long-term use in daily life. Because of the flexibility and durability of the carbon fiber and silicone rubber, the proposed coaxial fibers show great flexibility, which could be further knitted as cloth for sustainably powering wearable electronic devices. This work presents a promising platform for wearable electronics as well as smart textiles.

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