Nanomaterial-Based Electric and Electronic Gas Sensors

Great attention has been dedicated to the development and use of solid-state gas sensors based on nanostructured semiconductors in recent decades. Metal oxide semiconductors (MOSs) are definitely the most investigated materials, but they have shown several shortcomings, including the lack of selectivity and stability over time, which have limited their use in many applications. This has led researchers to design and synthesise advanced nanostructured materials based on other types of semiconductors, able to overcome the limitations of MOSs towards the development of devices with optimised sensing performance. Among several alternatives, nanostructured II–VI transition metal chalcogenides (TMCs) are promising candidates for gas sensor development, due to their very interesting physicochemical features. These include: (i) wide and tunable bandgap; (ii) size-tunable radiation absorption and emission; (iii) catalytic and photocatalytic properties and (iv) the possibility to tune the nanostructure morphology and crystal structure by using simple and inexpensive methods. Although scarcely investigated in the gas sensing field so far, preliminary studies published over the last 10 years have shown peculiar sensing properties of TMCs, which could open up a future integration of these materials into commercial gas monitoring devices. This chapter presents a critical analysis of the state of the art related to the synthesis and use of II–VI TMC nanomaterials (NMs) for the development of electrical and electronic gas sensors.