Abstract
Carbon monoxide (CO) gas is an odorless toxic combustion product that rapidly accumulates inside ordinary places, causing serious risks to human health. Hence, the quick detection of CO generation is of great interest. To meet this need, high-performance sensing units have been developed and are commercially available, with the vast majority making use of semiconductor transduction media. In this paper, we demonstrate for the first time a fabrication protocol for arrays of printed flexible CO sensors based on a printable semiconductor catalyst-decorated reduced graphene oxide sensor media. These sensors operate at room temperature with a fast response and are deposited using high-throughput printing and coating methods on thin flexible substrates. With the use of a modified solvothermal aerogel process, reduced graphene oxide (rGO) sheets were decorated with tin dioxide (SnO2) nanoscale deposits. X-ray diffraction data were used to show the composition of the material, and high-resolution X-ray photoelectron spectroscopy (XPS) characterization showed the bonding status of the sensing material. Moreover, a very uniform distribution of particles was observed in scanning (SEM) and transmission electron microscopy (TEM) images. For the fabrication of the sensors, silver (Ag) interdigitated electrodes were inkjet-printed from nanoparticle inks on plastic substrates with 100 µm linewidths and then coated with the SnO2-rGO nanocomposite by inkjet or slot-die coating, followed by a thermal treatment to further reduce the rGO. The detection of 50 ppm of CO in nitrogen was demonstrated for the devices with a slot-die coated active layer. A response of 15%, response time of 4.5 s, and recovery time of 12 s were recorded for these printed sensors, which is superior to other previously reported sensors operating at room temperature.
Highlights
Carbon monoxide (CO) is an acutely toxic gas as room temperature and ambient pressure that can accumulate in ordinary environments like homes and automobiles, causing poisoning and severe side effects in concentrations as low as 50 ppm
The solvothermal process to synthesize SnO2 -reduced graphene oxide (rGO) composites was previously reported in the literature [15]
In a first attempt to improve the material homogeneity and particle loading, the proportion of reagents used for the SnO2 synthesis (SnCl2, sodium acetate, and sodium citrate) relative to the graphene oxide was doubled
Summary
Carbon monoxide (CO) is an acutely toxic gas as room temperature and ambient pressure that can accumulate in ordinary environments like homes and automobiles, causing poisoning and severe side effects in concentrations as low as 50 ppm. The detection of CO gas at low partial pressures is challenging, mainly due to the odorless and colorless nature of the gas, and high-performance sensors are usually required to guarantee a safe detection response. CO sensors are based on the semiconductor SnO2 , since this technology affords a high response and robustness of operation [1]. These semiconductor-based sensors possess the advantage of being produced through methods from the microelectronics industry, meaning they can be . These characteristics have made SnO2 -based CO sensors commercially attractive in some applications. The bulk SnO2 sensor media typically must be heated to temperatures above 400 ◦ C to achieve a sufficient CO response [2,3]
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