RESUMO
Triboelectric nanogenerator (TENG) has been demonstrated as a sustainable energy utilization method for waste mechanical energy and self-powered system. However, the charge dissipation of frictional layer materials in a humid environment severely limits their stable energy supply. In this work, a new method is reported for preparing polymer film as a hydrophobic negative friction material by solution blending poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and polyvinyl chloride (PVC), doping with titanium dioxide (TiO2) nanoparticles, and further surface patterning modification. The P-TENG composed of the PVDF-HFP/PVC/TiO2 composite film with optimized hydrophobic performance (WCA = 124°) achieved an output voltage of 235 V and a short-circuit current of 35 µA, which is approximately three times that of the bare PVDF-HFP-based TENG. Under charge excitation, the transferred charge of the P-TENG can reach 35 nC. When the external load resistance is 5.5 MΩ, the output peak power density can reach 1.4 W m-2. Meanwhile, the hydrophobic surface layer with a rough surface structure enables the device to overcome the influence of water molecules on charge transfer in a humid environment, quickly recover, and maintain a high output. The P-TENG can effectively monitor finger flexibility and strength and realize real-time evaluation of the exercise state and hand fatigue of the elderly and rehabilitation trainers. It has broad application prospects in self-powered intelligent motion sensing, soft robotics, human-machine interaction, and other fields.
RESUMO
With the rapid development of triboelectric nanogenerators (TENGs), the exploration of self-powered, flexible, and wearable electronic devices has attracted widespread attention. However, the choice of tribomaterials and high humidity environment have a significant impact on the triboelectricity of TENG. Therefore, we prepared a composite fabric (HPC) with superhydrophobic and conductive properties, which was used simultaneously as a tribopositive material and electrode for the construction of promising wearable TENGs. Specifically, the loading of polydopamine, carbon nanotubes, and polypyrrole on the surface of the cotton fabric makes it have not only conductivity but also enhanced tribopositive polarity. Then, cetyltrimethoxysilane was selected to modify it to obtain superhydrophobicity. Compared with the common TENGs with a separate tribolayer and electrode, the integrated HPC-TENG shows the advantages of simpler structure and lighter wear. Moreover, compared with the unmodified fabric-based TENG, the performance of the proposed HPC-TENG is improved by nearly 7.2 times, and the maximum power density can reach 2.6 W m-2. This remarkable output can be attributed to the combination of strong electron-giving groups, high electrical conductivity, and abundant micro- and nanorough structure of the HPC fabric. More importantly, due to the water repellency of the fabric surface, the high output performance can be maintained under high humidity conditions. In addition, HPC-TENG has potential applications as pressure sensors for human motion status monitoring and multichannel sensing for smart game blanket entertainment. The newly designed HPC-TENG offers a new strategy for the development of superhydrophobic fabrics with an electrical conductivity, energy harvesting, and self-powered sensor.
RESUMO
As a sustainable, clean, and friendly technology with a minimal carbon footprint when treating seawater or wastewater, interfacial solar vapor generation (ISVG) technology is a great alternative to traditional desalination and water purification methods (e.g., reverse osmosis and ultrafiltration). So far, it presents tremendous potential for applications in realizing desalination of seawater or brine, wastewater treatment, and so forth. However, the precipitated salt particles during conventional ISVG inevitably block the evaporator surface, resulting in the degradation of photothermal conversion and decrease of evaporation rate. Herein, a multi-functional non-contact Janus hollow evaporator based on copper foam was prepared, which was assembled by a hydrophobic light-to-heat conversion layer and a hydrophilic interfacial water evaporation layer as two separate parts. Accordingly, the precipitated salt in the ISVG system does not block the photothermal interface, increasing the stability of solar capture and reusability of the evaporator. Notably, the hollow structure of the evaporator has a local interfacial heating effect, endowing the evaporation system with a high seawater evaporation rate of 2.249 kg m-2 h-1. The evaporator is capable of stable operation for 10 h under 1 sun illumination even when evaporating concentrated brine (15 wt %). Moreover, the evaporation rate of water under one sun irradiation reached 2.284 kg m-2 h-1 and the solar-to-vapor efficiency reached 96.6%. Not only that, the evaporator was able to successfully purify wastewater containing dyes and heavy metal ions. The multi-functional Janus hollow interfacial solar evaporator will provide inspiration for upcoming research on the production of safety water.
