Sputtered Grown Porous Nanostructured Materials: Achievements and Advances in Gas Sensing

Day by day, the demand for portable, low cost, and efficient chemical/gas-sensing devices is increasing due to worldwide industrial growth for various purposes such as environmental monitoring and health care. A vast amount of clinical evidence that establishes the link between public health and air quality, and the Organisation for Economic Co-operation and Development (OECD) estimates that by 2050, it may become the largest cause of premature mortality in the world, even surpassing drinking water scarcity and lack of sanitation. As well, poor air quality has contributed to over 4.2 million deaths globally. Due to that, there is a universal threat to the environmental and human health issues that invoke for the advanced technologies to identify toxic gases and organic vapors quickly. To fulfill this demand, porous thin films of nanostructured materials (large specific surface area and thus more active sites enabling higher absorption of oxygen and target gas, which obviously helps in improving the solid–gas interaction) developed by template- and catalyst- free sputtering technique can be used as active materials for gas sensors. In particular, uniquely designed porous nanostructured thin film materials exhibit a fast response, selectivity, and stability because the porous nanostructures provide effective gas diffusion path through the nanostructures without sacrificing the surface area, and therefore represent a very promising design option for gas sensors. Furthermore, the functionalization of nanomaterials and the fabrication of heterojunctions are other effective strategies to enhance their response and tune the selectivity to a specific gas. In this case, the formation of a p-n, p-p, or n–n interfaces is a significant factor to improve the reaction between the sensing structure and gaseous compounds. In this chapter, we have described the synthesis and characterization of different porous nanostructured materials such as CdTe/MoS2, Pd/MoS2, and CdTe/ZnO@PSi heterostructures using magnetron sputtering technique for gas sensing applications.