Conversion of low-grade heat via thermal-evaporation-induced electricity generation on nanostructured carbon films

Abstract

Nowadays, due to increasingly serious energy crisis and environmental pollution problems, conversion of ubiquitous low-grade heat to electricity is attracting increasing worldwide interests. Recently, energy-conversion methods mediated by molecular interactions between water and nanostructured carbon materials has been reported to directly harvest the environmental energy without any auxiliary equipment and energy input. Herein, we propose a method of conversion of low-grade heat by the thermal-evaporation-induced electricity generation on a porous nanostructured carbon films (NCFs). These NCFs are directly fabricated on an Al2O3 substrate and then pre-treated by annealing and UV/Ozone treatments to maintain the spontaneous water imbibition at high temperatures. This sample can unremittingly generate electricity at relative large temperature range (~22–82 °C) via the thermal-evaporation of water. This temperature range is a common temperature of low-grade heat sources. The maximum thermal-evaporation-induced voltages are measured to be about 0.79 ± 0.05 V, and the maximum output power is calculated to be approximately 80 nW with a power density of 150 μW/m2. Furthermore, our experimental results and theoretical analysis indicate that the substrate-property of NCFs can seriously influence the performance of thermal-evaporation-induced electricity generation.