Ten years＇ venturing in ZnO nanostructures： from discovery to scientific understanding and to technolosy applications

Zinc oxide is a unique material that exhibits semiconducting, piezoelectric and pyroelectric multiple properties. Nanostructures of ZnO are equally important as carbon nanotubes and silicon nanowires （NWs） for nanotechnology, and have great potential applications in nano-electronics, optoelectronics, sensors, field emission, light emitting diodes, photocatalysis, nanogenerators, and nanopiezotronics. Ever since the discovery of nanobelts （NBs） in 2001 by my group, a world wide research in ZnO has been kicked off. This review introduces my group＇s experience in venturing the discovery, understanding and applications of ZnO NWs and NBs. The aim is to introduce the progress made in my research in the last 10 years in accompany to the huge social advances and economic development taking place in China in the last 10 years.     

Self powered systems by nanogenerators and smart MEMS by piezotronics

Developing wireless nanodevices and nanosystems is of critical importance for sensing, medical science, environmental/infrastructure monitoring, defense technology and even personal electronics. It is highly desirable for wireless devices to be self powered without using battery, without which most of the sensor network may be impossible. The piezoelectric nanogenerators have the potential to serve as self sufficient power sources for micro/nano systems. For wurtzite structures that have non central symmetry, such as ZnO, GaN and InN, a piezoelectric potential (piezopotential) is created in the crystal by applying a strain. The nanogenerator is invented by using the piezopotential as the driving force for electrons to flow in respond to a dynamic straining of piezoelectric nanowires. A gentle straining can produce an output voltage of up to 20～50 V from an integrated nanogenerator. Furthermore, piezopotential in the wurtzite structure can serve as gate voltage that can effectively tune/control the charge transport across an interface/junction; electronics fabricated based on such a mechanism is coined as piezotronics, with applications in force/pressure triggered/controlled electronic devices, sensors, logic units and memory. By using the piezotronic effect, it is showed that the optoelectronic devices fabricated using wurtzite materials can have superior performance as solar cell, photon detector and light emitting diode. Piezotronic is likely to serve as “mechanosensation” for directly interfacing biomechanical action with silicon based technology and active flexible electronics. The paper gives a brief review about the basis of nanogenertors and piezotronics and their potential applications in smart MEMS (micro electro mechanical systems).     

Triboelectric nanogenerator as a new technology for effective PM2.5 removing with zero ozone emission

Particles matters (PMs) have raised serious concerns due to their great impact on human health. Coupling triboelectric effect and electrostatic induction, triboelectric nanogenerator (TENG) has demonstrated as a practical sustainable power source for portable devices. The characteristics of TENG, such as high electric field and high output power, make it a promising technology in air cleaning applications. Here, the mechanism of the TENG and its application in self-powered air cleaning technologies are reviewed. Using the TENG as a voltage source, a self-powered air cleaning system for removing SO₂ and PMs is developed; and the removal efficiency of nanofiber filters is greatly enhanced due to electrostatic attraction. More importantly, the technology is not only most effective for removing nano-scale particles that cannot be effectively filtered using conventional fiber-film filters, but also produces no ozone emission. Besides being an independent power supply, a vibration TENG based triboelectric filter is designed to effectively capture the PMs from automobile exhaust fumes. Hence, the TENG demonstrates its great potential in self-powered air cleaning applications.     

城市路网空间结构对住宅价格的影响分析

以链家房产交易平台和安居客房产交易平台的上海市二手住宅为研究样本,结合OpenStreetMap(OSM)提供的城市路网数据及高德地图提供的兴趣点(POI)等多源数据,利用空间句法测算路网空间结构的选择度和整合度.基于空间自回归模型、地理加权回归模型等空间计量估计方法,研究城市路网空间结构影响住宅价格的效果及机制.研究结果表明：城市路网空间结构是影响住宅价格的重要的区位因素,考虑空间相关性是必要的;与市中心住宅价格相比,郊区住宅价格对路网空间结构的依赖程度更强.     

摩擦纳米发电机在自驱动智能交通系统的应用研究进展

 摩擦纳米发电机具有供电和高灵敏度传感的双重功能,能够在自驱动智能交通系统中发挥重要作用。综述了近年来摩擦纳米发电机在公路及铁路智能交通系统中的应用,包括车辆检测、尾气处理、振动能收集、风能收集等,分析了摩擦纳米发电机在智能交通系统应用过程中存在的挑战,展望了摩擦纳米发电机在材料、信息、电子、机械、交通等多学科交叉的发展趋势。     

生物可降解能源器件及其应用

 植入式瞬态电子器件由可降解材料构建而成,这些电子器件能够在体内降解并吸收,无需二次手术取出,避免了长期植入产生的负面效应。作为一个新兴的研究领域,植入式瞬态电子器件在体内传感和治疗方面都有着巨大的潜能。然而,大多数植入式瞬态电子器件的正常工作都需要外部能源供给,这极大限制了它们在体内的应用。因此,一种具有生物相容性、可控降解和生物可吸收的新式生物可降解能源器件,成为了植入式瞬态电子器件的迫切需求。介绍了4种生物可降解能源器件（生物可降解原电池、光伏电池、超级电容器和摩擦纳米发电机）及其应用,并探讨了各自所面临的挑战和未来发展趋势。     

基于超弹性PDMS的摩擦纳米发电机的性能研究

常用于摩擦纳米发电机的聚二甲基硅氧烷是一种超弹性聚合物,但迄今对其理论分析均采用线弹性本构假设,没有通过实验证明其是否有效.首先基于超弹性本构对PDMS摩擦纳米发电机的接触力学和静电感应性能进行仿真;其次通过光刻和复型工艺制备了PDMS金字塔织构,构建了摩擦纳米发电机实验装置,并将实验与理论结果对比.研究表明:随着施加压力增大,摩擦纳米发电机的接触面积和开路电压均随之增加,之后趋于稳定;相比于超弹性本构,采用线弹性本构高估了金属与PDMS的接触面积,低估了使摩擦纳米发电机开路电压稳定所需施加的压力;采用超弹性PDMS本构的仿真结果与实验更为吻合.      

摩擦纳米发电机研究可视化图谱分析

全球范围内能源与环境问题日益严峻,自从2012年摩擦纳米发电机（Triboelectric Nanogenerator）的概念被提出以来,作为一种清洁可再生的微纳新能源产生装置,成为众多研究人员关注的焦点。基于CiteSpace可视化分析软件,针对Web of Science数据库中检索到的1908篇摩擦纳米发电机研究领域论文从出版年、引用次数、发文期刊、机构、作者和关键词等角度进行图谱分析,总结摩擦纳米发电机领域国内外研究进展和热点并预测前沿趋势,为深入了解摩擦纳米发电机领域的研究现状提供借鉴和参考。     

基于摩擦纳米发电机的自供能发光地板系统

为保证物联网中承担着信息采集与传输等重要任务的传感器持续、稳定、免维护地工作,其中一种解决方案为收集广泛分布在环境中的振动机械能,构建自供能系统。而摩擦纳米发电机(TENG)作为机械能俘获技术之一,在收集低频无规则振动机械能方面具有更高的能量转换效率。因此,针对人行走时产生的振动机械能,设计并制作了硅胶半球支撑的接触分离式TENG。该TENG器件在1 Hz频率下的开路电压峰值为348 V,短路电流峰值为7.7μA,外接40 MΩ电阻时瞬时功率可达265μW,将它与树脂浇筑构建的硬质板面集成,则可实现自供能发光地板系统,能够在不同人流量的条件下正常工作。该发光地板可应用于人群密集的商场、步行街、游乐园等场所。     

微纳系统中的可持续自供型电源: 能源研究中的新兴领域

自从手提电脑和手机等个人可移动电子产品普及以后, 解决小范围的用电显得格外重要. 我们目前主要靠的是蓄电池. 在未来不久, 由于微纳系统的发展以及它们在原位人体健康的实时监测、基础设施的监测、环境监测、物联网以及军事技术上的应用, 传统的利用蓄电池来提供电源的方法将不能满足或不能适应传感器网络的工作环境和要求. 在2005年, 作者提出了自驱动的概念, 其根本是利用从环境中收集的能量, 通过能量转换来驱动这些微纳系统, 实现功率自给. 本文介绍作为微纳系统中可持续自供型电源的一种——纳米发电机的研究和未来应用.