Vertically Aligned Lead Titanate Nanowire Arrays for High Temperature Energy Harvesting

Over the past few decades, the increasing demand for self-powered devices has led to an immense amount of research in the field of energy harvesting from renewable mechanical energies. Often, most of these abundant energy sources are wasted in the form of structural vibrations, acoustic waves or impact energy. Recently, nano-electromechanical systems (NEMS) consisting of piezoelectric nanowires have shown excellent electromechanical coupling coefficients which can efficiently convert small amplitude vibrations into useful electrical energy for compact and low power wireless electronic devices. Specifically, high aspect ratio piezoelectric nanowires have shown to have a better deformability and hence produce higher piezoelectric response to low level induced stress. However, current materials are not well suited for energy harvesting from extreme environments. In this study, ultra-long high aspect ratio vertically aligned lead titanate nanowires (45 μm long, AR = 75) are synthesized through a two-step hydrothermal reaction in which sodium titanate nanowires serve as the precursor. Their application in harvesting vibrational energy at temperatures above 300 °C is demonstrated through the characterization of open circuit voltage and power measurements. The results show that the ultra-long vertically aligned lead titanate nanowire array energy harvester can produce up to 22.3 mW m⁻² at room temperature and up to 13 mW m⁻² at 375 °C. Thus, it is shown that the energy harvester can provide enough energy density for many self-powered, high-temperature applications.