Exploring the Gas Sensing Potential of Cross-Linked Asphaltene: A Promising Application of an Affordable Material.

In recent years, there has been significant research interest in carbon-based nanomaterials as promising candidates for sensing technologies. Herein, we present the first utilization of asphaltenes as an affordable, cost-efficient carbon-based material for gas sensing applications. Asphaltenes, derived from various oil sources, are subjected to facile cross-linking reactions to produce nanoporous carbon materials, where the asphaltene molecules from different layers are interconnected via covalent bonds. The characterization results of these cross-linked asphaltenes revealed substantial enhancement in their specific surface area and surface functionality. Quartz crystal microbalance sensors with sensing films derived from various asphaltene samples were prepared to detect different ethanol concentrations at room temperature. All the cross-linked asphaltene samples showed a significant enhancement in the sensing response (up to 430%) compared to that of their respective raw parent samples. Such a response of the cross-linked asphaltene samples was comparable to that obtained from graphene oxide. The sensor based on cross-linked asphaltenes demonstrated good linearity, with a response time of approximately 2.4 min, a recovery time of around 8 min, and an excellent response repeatability. After 30 days, the sensor based on cross-linked asphaltenes showed approximately 40% reduction in its response, suggesting long-term aging. This decline is partially attributed to the observed swelling. The current study opens the door to a deeper exploration of asphaltenes and highlights their potential as promising candidates for sensing applications.