Desenvolvimento de termocélulas nanoestruturadas do tipo em camadas e coplanar

Abstract

Environmental problems accentuated by fires and fossil fuels reflect the need to develop more accurate environmental monitoring systems, as well as the reuse of waste heat in thermoelectric conversion in industrial processes. Thus, in this research, thermocells based on Buckypaper (BP) were developed in two arrangements: layered and coplanar. BP was produced by vacuum filtration of functionalized Carbon Nanotubes (f-CNTs) through a filter paper with 14 μm pores. Scanning Electron Microscopy showed a BP consisting of cellulose fibers impregnated with agglomerated f-CNTs. By measuring two-point, a BP tape (1.0 cm2) showed an electrical resistance of 0.92 kΩ at 300 K. When heated in the range of 300-337 K, the BP reduced on average 22.39% of its electrical resistance, characterized as a thermoresistor. In the layered thermocell, keeping the copper electrode at room temperature while the BP electrode (active area: 5.5 cm2 ) was thermally excited generated a thermoelectric power (α) of 26.33 mV/K for ΔT = 3.0 K. This result is superior to that reported in nanostructured thermoelectrochemical cells and is close to that obtained by commercial silicon. In the coplanar thermocell, the BP was connected between two copper electrodes that acted as hot and cold sides (cooled by a heatsink) and reached α = -0.06 mV/K for ΔT = 19 K. This result was inferior to that obtained for Bi2Te3 and superior to that obtained by a free-standing BP based on nitrogen-doped CNTs.