Ceria Quantum Dot-Decorated Carbon Nanotubes as a Room-Temperature Acetone Sensor

Abstract

Recently, low-dimensional semiconducting metal oxide (SMO) nanostructures have revolutionized the concept of conventional SMO-based chemiresistive gas sensors owing to their unique catalytic, electrical, and optical properties. The elevated working temperature of SMO-based sensors can be lowered by incorporating carbonaceous materials. Herein, we report for the first time, the superior acetone sensing performance at room temperature (RT, 27 °C) using ceria (CeO2) quantum dots (QDs) (7 ± 1 nm)-decorated carbon nanotube (CNT)-based nanocomposites. A hydrothermally prepared CeO2 QDs/CNT mesoporous heterostructure with a high surface area (152 m2 g–1) exhibits an excellent response (G a/G g) of 10,890 at RT with an ultrafast response/recovery time (56 ms/22 ms) and high selectivity toward acetone. The study unveils that the nanocomposite possesses simultaneous full and partial recovery response transients which is modeled using a heterogeneous adsorption site-based Langmuir–Hinshelwood mechanism. Besides, the mesoporosity of the nanocomposite results in fast diffusion of acetone molecules which reduces the detection time and incorporation of highly conductive CNTs lowers the operating temperature. The presence of Ce3+ states confirms the existence of high oxygen vacancies in CeO2 QDs resulting in enhanced adsorption capabilities of the nanocomposite. Moreover, the multi nanojunctions between CeO2 QDs and CNTs have a strong influence on the enhanced RT acetone response value.

Cs2AgBiBr6 Quantum Dots Supported on Co3O4 Nanocages for Acetone Detection at Room Temperature

“…From Figure b, it can be seen that once the target is injected into the laboratory, a sensing reaction occurs between the preadsorbed oxygen species (O 2 – ) and the target gas (acetone). The relevant transition process can be described by the following equation: normalC normalH 3 COC normalH 3 ( g ) → normalC normalH 3 COC normalH 3 ( ads ) normalC normalH 3 COC normalH 3 ( ads ) + 4 normalO 2 − → 3 normalC normalO 2 + 3 normalH 2 normalO + 4 normale − Therefore, due to the large number of free electrons returning to the conduction band of Co 3 O 4 , the CABB QDs-Co 3 O 4 sensor has achieved a significant narrowing of the hole accumulation layer and an increase in sensor resistance. In short, due to the large specific surface area, a large amount of O 2 – generation, and the formation of p-p heterojunctions, the CABB QDs-Co 3 O 4 sensor exhibits enhanced gas sensing performance under RT.…”

“…The interaction energy between acetone molecules and oxygen ions may be high because acetone is a polar molecule with a high dipole moment of 2.91 D compared to other polar VOCs (ethanol, methanol, formaldehyde, etc.). 53 Also, the high selectivity to acetone may be due to the low bond dissociation energy of acetone (352 kJ/mol) than other gases such as ethanol (462 kJ/mol), methanol (462 kJ/mol), toluene (371 kJ/mol), ammonia (391 kJ/mol), and formaldehyde (368 kJ/mol). 54 This enables acetone gases to easily react with the surfaceadsorbed oxygen ionic species.…”

“…From Figure 9b, it can be seen that once the target is injected into the laboratory, a sensing reaction occurs between the preadsorbed oxygen species (O 2 − ) and the target gas (acetone). The relevant transition process can be described by the following equation: 53 CH COCH (g) CH COCH (ads)…”