Search

MXenes are a class of 2D transition-metal carbides, nitrides, and carbonitrides with exceptional properties, including substantial electrical and thermal conductivities, outstanding mechanical strength, and a considerable surface area, rendering them an appealing choice for gas sensors. This manuscript provides a comprehensive analysis of heterostructures based on MXenes employed in gas-sensing applications and focuses on addressing the limited understanding of the sensor mechanisms of MXene-based heterostructures while highlighting their potential to enhance gas-sensing performance. The manuscript begins with a broad overview of gas-sensing mechanisms in both pristine materials and MXene-based heterostructures. Subsequently, it explores various features of MXene-based heterostructures, including their composites with other materials and their prospects for gas-sensing applications. Additionally, the manuscript evaluates different engineering strategies for MXenes and compares their advantages to other materials while discussing the limitations of current state-of-the-art sensors. Ultimately, this review seeks to foster collaboration and knowledge exchange within the field, facilitating the development of high-performance gas sensors based on MXenes. [ABSTRACT FROM AUTHOR]

Due to its harmful nature, carbon monoxide (CO) should be detected at low temperature and in a wide range of CO concentration. A sensor based on WO3–graphene nanocomposite synthesized by the solvothermal method has been developed. Based on material characterizations, the synthesized monoclinical WO3 has a nanowire shape. The presence of graphene interestingly promoted the formation of the WO3 hexagonal structure as a minor phase in the composite. The gas sensor measurements were carried out at three different temperatures, 300 °C, 150 °C, and room temperature. It was found that at 300 °C, the composite with ratio WO3:graphene 2:1 or WG21 produces a 21.5 response value to 10 ppm of CO, which is higher than the other composites. The response and recovery times of WG21 are 16 and ∼4.4 min, respectively. The WG21 nanocomposite was also found to show a good sensitivity in the range concentration of 10–300 ppm. [ABSTRACT FROM AUTHOR]

A simple method to synthesize graphene-zinc oxide nanocomposite has been developed. A reduced graphene oxide-ZnO nanocomposite was prepared using a reflux method with ethylene glycol as medium. X-ray diffraction analysis, scanning electron microscopy, energy-dispersive spectrometry, and nitrogen adsorption-desorption measurements were used to characterize the resulting composite materials. The highest response of about 98% was observed when using pure ZnO at 300°C, while the second highest sensor response of about 96% was achieved by graphene-ZnO with 1:3 composition. It was found that the graphene-zinc oxide hybrid has potential to improve sensor performance at low temperature. The graphene-ZnO hybrid with 1:3 composition showed good response of 36% at 125°C, an operating temperature at which pure ZnO showed no response. [ABSTRACT FROM AUTHOR]

SnO2-graphene nanocomposite thick films have been successfully synthesized using polyol method. Reflux with ethylene glycol as medium was employed to produce the nanocomposite. Crystal structure characterization using X-Ray diffraction shows the nanocomposites have good crystalinity without any impurity. Scanning electron microscopy and transmission electron microscopy characterization results show SnO2 has spherical shape and well distributed on the graphene layer. The size of SnO2 particles is around 5–8 nm. To confirm the improvement effect of grapheme addition to SnO2, sensor testing was conducted toward 30 ppm carbon monoxide (CO) gas at 150 °C compared with pure SnO2 and pure graphene. The sensor responses are 88.11%, 52.84%, and 0.93%, respectively. [ABSTRACT FROM PUBLISHER]

A significant amount of pollutants is produced from factories and motor vehicles in the form of gas. Their negative impact on the environment is well known; therefore detection with effective gas sensors is important as part of pollution prevention efforts. Gas sensors use a metal oxide semiconductor, specifically SnO2 nanostructures. This semiconductor is interesting and worthy of further investigation because of its many uses, for example, as lithium battery electrode, energy storage, catalyst, and transistor, and has potential as a gas sensor. In addition, there has to be a discussion of the use of SnO2 as a pollutant gas sensor especially for waste products such as CO, CO2, SO2, and NOx. In this paper, the development of the fabrication of SnO2 nanostructures synthesis will be described as it relates to the performances as pollutant gas sensors. In addition, the functionalization of SnO2 as a gas sensor is extensively discussed with respect to the theory of gas adsorption, the surface features of SnO2, the band gap theory, and electron transfer. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZnO-Ag layer was deposited on flexible substrate of PET-ITO using electrodeposition technique. • The amount of Ag affect the morphology of the prepared ZnO. • 0.6 mM of Ag resulted in low density of nanosheets with many homojunctions. • A flexible sensor of ZnO-Ag shows responses of 5.65 % and 16.01%–30 and 100 ppm of ethylene respectively at room temperature. As a versatile semiconductor material, ZnO has been investigated in many areas. One of the ZnO potential application is its use as the sensing materials, especially for gas sensors. In this study, ethylene gas sensor is successfully fabricated using ZnO-Ag layer on a flexible PET-ITO substrate using a simple electrochemical deposition process. The morphological and structural properties of the layer are characterized and related to the sensors' performance. From the result, it is shown that the ethylene sensing works best on a smaller crystallite size ZnO-Ag layer, with the most evenly coverage layer. The optimum sensor was made using ZnO and 0.6 mM of Ag. This sensor showed a relative change in resistance or a response value of 5.65 % and 16.01 % under ethylene gas exposure at 30 and 100 ppm, respectively. [ABSTRACT FROM AUTHOR]