Preparation of High-Performance Composite Films for Wearable Electronic Devices and Their Properties
Two-dimensional transition metal dichalcogenides (TMDs) have unique physical and chemical properties due to their unique electronic structure, diverse chemical composition and good material properties, and have been widely studied and applied in the fields of catalysis, electronics, biosensing, energy conversion and storage. Therefore, based on the research progress of preparing composite films for wearable electronic devices based on two-dimensional materials, we have prepared composite films based on ZIF-8@MoS 2nanoparticles and applied them to wearable electronic devices. Compared with traditional optoelectronic materials, MoS2 layered materials have a larger application space in the field of flexible devices due to their good mechanical flexibility. ZIF-8@MoS 2/PDMS composite film is used as a high-efficiency TENG electrical material, which can effectively increase the output performance of TENG. Experiments show that the maximum peak short-circuit current (I sc) and open-circuit voltage (V oc) of this TENG can reach 6.2μA and 194V, respectively, when ZIF-8@MoS 2particles are incorporated. When a resistor from 0 Ω to 10 3MΩ was used as an external load to evaluate the electrical output performance of TENG prepared based on ZIF-8@MoS 2/PDMS composite film, it was found that the output voltage also increased with the increase of resistance, and the output peak value was much higher than that of TENG prepared by pure PDMS. In addition, both the short-circuit current and open-circuit voltage increase with frequency from 1 Hz to 10 Hz, peaking at 10 Hz and about 6.2 μA and 194 V, respectively. The experimental results also show that this electronic device has good stability and output performance, which provides a certain reference value for the development of flexible wearable devices in the future.
Triboelectric Nanogenerators
TENG主要是由摩擦起电产生电荷,再通过静电感应产生电势差使得电荷发生转移,从而产生电流。通过周期性运动产生的电信号,将机械能转化为电能。因此,摩擦过程中材料对电子的束缚能力和材料之间的相对极性十分重要
摩擦纳米发电机是收集机械能的最简单有效的方法之一
虽然近几年TENG发展迅速,但是该研究领域的未来发展仍存在一些问题需要解决。(1) 提高TENG的输出能量:从内部看,现在很多研究通过改性材料或创建表面微纳米结构来增强接触亲密度,从而提高表面电荷密度。从外部可以优化工作环境,引入电源管理电路,例如,电荷泵送和自充电励磁是提高TENG输出功率的2种新开发的有效机制。(2) 提高材料和设备的耐久性:长期稳定性是TENG实际应用的关键问题,使用过程中,材料的磨损会导致性能的下降,可以通过设计接触式与非接触式的切换,或者通过新材料引入来提升输出性能和耐用性。(3) 降低TENG材料对环境的影响:TENG的材料大多是不可降解的合成聚合物,可能会造成环境污染,可生物降解和可再生材料却往往具有不足的摩擦电和机械性能,天然材料的探索还需进一步的研究来完善。(4) TENG的有效储能:传统的储能设备通常使用直流输入充电。鉴于TENG的脉冲输出特性,研究锂电池中脉冲驱动力作用下离子在隔离膜上的传输和扩散非常重要,这将进一步扩大TENG的应用范围。
钼酸铵(分析纯,上海麦克林生物化学有限公司),硫脲(分析纯,西陇科学股份有限公司),无水乙醇(分析纯,上海阿拉丁试剂有限公司),硝酸锌(分析纯,国药集团化学试剂有限公司),2-甲基咪唑(分析纯,上海阿拉丁试剂有限公司),聚乙烯吡咯烷酮(分析纯,上海源叶生物科技有限公司),PDMS预聚物和固化剂(分析纯,道康宁)
本文主要采用一步水热法得到ZIF-8@MoS2,具体如下所示,将1.356 g四水合钼酸铵和2.66 g硫脲完全溶解在35 mL DI中,并超声至均匀分散。随后转移至聚四氟乙烯水热反应釜中,200℃下反应10 h。冷却至室温后将产物转移至烧杯中,超声30min,最终产物离心并用DI洗涤3次。使用超声细胞破碎机在冰浴中超声MoS2纳米晶体30 min,随后将处理过的MoS2纳米晶体(1 mL, 1 mg/mL)添加到20 mL DI中。将0.4 mg PVP添加到溶液中并超声15 min,随后将0.08 g Zn (NO3)2·6H2O (5 mL去离子水)添加到上述溶液中。搅拌20 min后,将0.22 g 2-甲基咪唑溶解在5 mL DI中,并在恒定搅拌下滴入到反应液中。反应10 h后,将最终产物离心并用DI洗涤。60℃烘箱下干燥过夜即可得到ZIF-8@MoS2。
首先,称取1 g PDMS预聚物,固化剂与预聚物的质量比为1:10,将两者混合均匀后加入1 m‰ ZIF-8@MoS2纳米颗粒,混合搅拌后用300 μm刮刀涂膜。随后放入真空烘箱中抽真空15 min,最后在90℃烘箱中干燥2 h成膜。
用X射线粉末衍射(PXRD,BRUKER AXS D8 Advance,Cu Kα)在2θ范围内(10°~80°)进行扫描,扫描速度为5 deg. /min,对所制备的ZIF-8纳米晶体和ZIF-8@MoS2纳米颗粒的物相进行表征。在场发射扫描电子显微镜(FESEM,ZEISS Gemini SEM 300)上观察ZIF-8@MoS2纳米颗粒的详细形貌。
*通讯作者。