Degradation of Organic Dyes by the UCNP/h-BN/TiO2 Ternary Photocatalyst.

In this study, upconversion nanoparticles (UCNPs) with a flower-like morphology were prepared using a urea coprecipitation method. A ternary photocatalyst was first prepared using a solvothermal method involving the use of titanium oxide (TiO2), hexagonal boron nitride (h-BN), and UCNPs (Y2O3, Yb3+, and Tm3+) as raw materials. The surface morphology, crystal structure, and functional groups of these materials were then characterized and analyzed through scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, ultraviolet-visible spectrophotometry, and other techniques. Photocatalytic experiments were also conducted to investigate the effects of different catalyst types, raw material doping ratios, pH values, and catalyst quantities on the photocatalytic degradation of rhodamine B (RhB). The results indicated that doping with h-BN and UCNPs reduced the band gap width of RhB, increased its light absorption rate, and decreased the recombination rate of its photogenerated electrons and holes so that the photocatalytic degradation effect reached 100% within 2 h. After five experimental cycles, the 30% UC-BN-Ti photocatalyst remained highly durable and stable. To investigate the effects of different trapping agents on the degradation of RhB, benzoquinone, isopropanol, and ethylenediaminetetraacetic acid disodium salt were used as free-radical-capturing agents. The results indicated that •O2- was the primary active species in the degradation process. Finally, the pathway and mechanism of the degradation of RhB through ternary composite photocatalysis were identified.

Flexible Self-Repairing Materials for Wearable Sensing Applications: Elastomers and Hydrogels.

Flexible pressure and strain sensors have great potential for applications in wearable and implantable devices, soft robots, and artificial skin. The introduction of self-healing performance has made a positive contribution to the lifetime and stability of flexible sensors. At present, many self-healing flexible sensors with high sensitivity have been developed to detect the signal of organism activity. The sensitivity, reliability, and stability of self-healing flexible sensors depend on the conductive network and mechanical properties of flexible materials. This review focuses on the latest research progress of self-healing flexible sensors. First, various repair mechanisms of self-healing flexible materials are reviewed because these mechanisms contribute to the development of self-healing flexible materials. Then, self-healing elastomer flexible sensor and self-healing hydrogel flexible sensor are introduced and discussed respectively. The research status and problems to be solved of these two types of flexible sensors are discussed in detail. Finally, this rapidly developing and promising field of self-healing flexible sensors and devices is prospected.

Convenient CNT-Paper Gas Sensors Prepared by a Household Inkjet Printer.

A hydrosoluble light-sensitive polymer named PSAG (poly-styrenesulfonate acrylic acid glycidyl methacrylate) was synthesized by acrylic acid (AA), sodium 4-styrenesulfonate (SS), and glycidyl methacrylate (GMA). PSAG is used to modify multiwall carbon nanotubes (MWCNTs) with a length diameter between 0.004 and 0.016. An inkjet conductive ink was formed by well-dispersed MWCNTs in aqueous and organic solvents, which could adjust the surface tension and viscosity of the ink. Gas sensors were then fabricated using this conductive ink on a household inkjet printer. The sensors demonstrated good reproducibility and acceptable recovery time (<200 s) to ammonia, methanol, and acetone. The resistance of the inkjet-printed sensor electrodes remained stable in the process of bending the sensors to different angles because of ultraviolet curing.

Three-Dimensional Porous Carbon Nanotubes/Reduced Graphene Oxide Fiber from Rapid Phase Separation for a High-Rate All-Solid-State Supercapacitor.

Graphene fiber-based supercapacitors (SCs) are rising as having the greatest potential for portable/wearable energy storage devices. However, their rate performance is not well pleasing, which greatly impedes their broad practical applications. Herein, three-dimensional porous carbon nanotube/reduced graphene oxide fibers were prepared by a nonsolvent-induced rapid phase separation method followed by hydrazine vapor reduction. Benefitting from their three-dimensional porous structure, large specific surface area, and high conductivity, the fabricated SC exhibits a high volume capacitance of 54.9 F cm-3 and high energy and power densities (4.9 mW h cm-3 and 15.5 W cm-3, respectively). Remarkably, the SC works well at a high scan rate of 50 V s-1 and shows a fast frequency response with a short time constant of 78 ms. Furthermore, the fiber-shaped SC also exhibits very stable electrochemical performances when it is subjected to mechanical bending and succeeding straightening process, indicating its great potential application in flexible electronic devices.