Abstract
Oxide semiconductors are conventionally used as sensing materials in gas sensors, however, there are limitations on the detection of gases at room temperature (RT). In this work, a hybrid of copper oxide (CuO) with functionalized graphene (rGO) is proposed to achieve gas sensing at RT. The combination of a high surface area and the presence of many functional groups in the CuO/rGO hybrid material makes it highly sensitive for gas absorption and desorption. To prepare the hybrid material, a copper oxide suspension synthesized using a copper acetate precursor is added to a graphene oxide solution during its reduction using ascorbic acid. Material properties of the CuO/rGO hybrid and its drop-casted thin-films are investigated using Raman, FTIR, SEM, TEM, and four-point probe measurement systems. We found that the hybrid material was enriched with oxygen functional groups (OFGs) and defective sites, along with good electrical conductivity (Sheet resistance~1.5 kΩ/□). The fabricated QCM (quartz crystal microbalance) sensor with a thin layer of the CuO/rGO hybrid demonstrated a high sensing response which was twice the response of the rGO-based sensor for CO2 gas at RT. We believe that the CuO/rGO hybrid is highly suitable for existing and future gas sensors used for domestic and industrial safety.
Highlights
Over the past few decades, the environment has been heavily filling with toxic, inflammable, and harmful gases due to the unceasing development of industries and deforestation [1]
The CuO/rGO hybrid and rGO-based gas sensors are investigated for CO2 gas sensing capability at room temperature
Fourier Transform Infrared (FTIR) spectrum is used to identify the presence of functional groups and chemical compounds
Summary
Over the past few decades, the environment has been heavily filling with toxic, inflammable, and harmful gases due to the unceasing development of industries and deforestation [1]. CuO is a p-type semiconductor and has a narrow bandgap of 1.2–1.9 eV and exhibits excellent properties that have been utilized in a number of applications such as electrode materials for lithium-ion batteries, thinfilm electrodes [25,26], catalysts [21], and gas sensors [27]. These CuO sensing materials need a high temperature to operate, which limits its gas sensing capability at room temperature. We report a CuO/functionalized graphene (rGO) hybrid nanostructure as a promising sensing material for QCM-based sensors for detecting gas at room temperature. The CuO/rGO hybrid and rGO-based gas sensors are investigated for CO2 gas sensing capability at room temperature
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