Development of Low-Dimensional Materials in Energy Scavenging

Abstract

This thesis work reported the development of low-dimensional material for energy scavenging. The study was separated into three parts, studying the energy scavenging methods, preparation and characterization of piezoelectric materials, and application in energy scavenging. The energy that was interested in this work was mechanical that was ambient energy in daily life. The energy could be either factory scale or human scale. To scavenge the energy, piezoelectric method was elected because the piezoelectric method provided the high voltage output and small mechanical damping without an external voltage source. The piezoelectric method used the material with non-centrosymmetric property to convert the mechanical energy into electrical energy. The second part was the material processing. The piezoelectric materials that was observed in this work were ZnO and P(VDF-HFP). ZnO had gained widespread attention in many application, for example,. electronic, optic cosmetic, and energy harvesting. In the energy harvesting application, ZnO was found that the piezoelectric property was greater when the size of ZnO was reduced into nanoscale. In this work, ZnO was prepared via hydrothermal method. The effect of precursor, concentration and solvent were observed. Macrorod, nanorod and nanoparticle were successfully prepared. The polarity of the solvent was found to be the main parameter to determine the size of ZnO. Amount of 10 nm diameter was obtained when the ZnO was prepared in methanol. The prepared ZnO were characterized by using atomic force microscopy base. Topography, piezoresponse force microscopy (PFM) and force-distance curve were studied. From PFM resulted, prepared ZnO was piezoelectric material and the method could identify the direction of growing. ZnO was also observed for bioengineering application by mixing the ZnO into collagen film. The mechanical properties of the reinforce was observed by force-distance microscopy. From the result, ZnO enhanced the young’s modulus and thermal stability of the collagen. In energy harvesting application, ZnO was mixed into electroactive polymer P(VDF-HFP) to maximize the energy power. The effect of size, shape, and concentration of ZnO were tested. The result showed that the composite film 2 wt% ZnO nanorod P(VDF-HFP) generated electrical power upto 1 μW that the power was enough for low-power microcontroller.