Nanotubos de carbono decorados com óxido de ferro aplicados a sensores de gás

Abstract

The study of hydrogen gas sensors (H2) arises from the need to monitor such gas of wide use in the industries and processes of environmental monitoring. Thus, H2 sensors are required because this gas has a low molecular weight, can cause explosions because it is odorless, colorless and tasteless. Thus, in this work, a study is presented on devices based on gas sensors made from carbon nanotubes (CNT) functionalized with iron oxide and also CNTs modified by thermal treatment and chemical attack. Thus, a gas sensor characterization system was developed with the objective of studying the adsorption process and morphology of these materials, the CNT, CNT being chemically and thermally treated, iron oxide and functionalized materials, that is, CNT decorated with iron oxide in the following proportions, 4000:1, 2000:1 and 1000:1 respectively. For the structural and morphological characterization, analyzes were performed by Scanning Electron Microscopy, Infrared Spectroscopy and Profiometry of the materials used in the active layer of the sensor. All materials were deposited on interdigitated electrodes using the spray technique and the electrical properties were analyzed in the presence of the studied gas. The material that presented the highest gas response (R = 115.0%) was the sample with the lowest iron 4000:1 CNT /Fe(NO3)39H2O ratio. The lowest mean response time was observed in the chemically treated CNT (52.3 seconds) and the lowest average recovery time (145.6 seconds) in the 2000:1 CNT /Fe(NO3)39H2O intermediate sample. In this way, it was verified that the sample that exhibited the best performance was the one with the lowest proportion of iron oxide, and the best composition of the CNT / iron oxide mixture was used for the monitoring of H2 in the medium. The temperature of evaluation of the measurements of the response of the sensor was at 160ºC.