Multilayer Structure of Reduced Graphene Oxide and Copper Oxide as a Gas Sensor

Abstract

Reduced graphene oxide and copper oxide multilayer structures were fabricated in a planar configuration by deposition on both ceramic and Si/SiO2 substrates with interdigitated Au electrodes by the spray method. SEM (scanning electron microscopy), TEM (transmission electron microscopy), XRD (X-ray diffraction), and elemental analysis investigations indicated that graphene oxide (GO) was obtained in a form of interconnected flakes consisting of 6–7 graphene layers for GO with the total thickness of ca. 6 nm and 2–3 layers for rGO with the total thickness of 1nm. The lateral size of one flake reached up to 10 micrometers. Copper oxide was obtained by the wet chemical method. The number of sequential layers of the sensing structure was optimized to obtain good sensitivity and acceptable response/recovery times in response to the oxidizing nitrogen dioxide atmosphere. Both semiconductor partners revealed p-type conductivity. Formation of isotype heterojunctions between both semiconductor partners was taken into account and their influence on electrical transport explained. Optimized sensor structures revealed relative sensitivities reaching several tens of percent and acceptable response and recovery times in NO2 concentration ranged from a few to 20 ppm. Possibility of manufacturing sensors working at room temperature was shown, but at the cost of prolonged response/recovery times.

Nitrogen Dioxide Sensing Using Multilayer Structure of Reduced Graphene Oxide and α-Fe2O3

“…At the interface between rGO flakes and Fe 2 O 3 grains, the p-n heterojunctions can be formed. The numerical value of work function for rGO was taken from [ 41 ], and the energy gap was evaluated from [ 42 ] for oxygen content in rGO equal O/C = 10%, as previously determined in elemental composition experiments [ 40 ]. The work function for Fe 2 O 3 was taken from Guo et al [ 31 ].…”

“…The required NO 2 gas concentration was obtained by controlling the ratio of gas to airflow rates. The humidity of the gas atmosphere was always kept constant with RH = 50% (detailed description of the measurement setup is given in [ 40 ]).…”

The Heterostructures of CuO and SnOx for NO2 Detection

“…Measurements of the sensor properties of the prepared samples were performed on a dedicated setup, consisting of a measuring chamber with a volume of about 300 cm 3 , with the possibility of regulating and stabilizing the temperature of the sensor in the chamber (previously presented in [ 48 ]). The target gases were supplied to the chamber via MFC controllers from gas canisters (Air Liquid, Cracow, Poland) with various initial concentrations ranging from 0.5–20 ppm.…”

Highly Efficient MoS2/CsxWO3 Nanocomposite Hydrogen Gas Sensors

“…A polluted atmosphere endangers the health of living organisms. It comprises various gases that exist in nature and those released from industries (Masteghin et al, 2019;Pisarkiewicz et al, 2020;Duc et al, 2020;Kim et al, 2021). These odorless, tasteless, colorless gases are toxic when they exceed the safe limits (Ha et al, 2018;Miglietta et al, 2020;Pisarkiewicz et al, 2020).…”

“…It comprises various gases that exist in nature and those released from industries (Masteghin et al, 2019;Pisarkiewicz et al, 2020;Duc et al, 2020;Kim et al, 2021). These odorless, tasteless, colorless gases are toxic when they exceed the safe limits (Ha et al, 2018;Miglietta et al, 2020;Pisarkiewicz et al, 2020). Hydrogen (H 2 ), carbon dioxide (CO 2 ), carbon monoxide (CO), and ammonia (NH 3 ) present in the environment have adverse effects on human health when their concentrations exceed the permissible levels (Annanouch et al, 2021;Hübert et al, 2014;Saravanan et al, 2017).…”