Nanoscale Heterostructured Materials Based on Metal Oxides for a Chemiresistive Gas Sensor

Nanomaterials with exceptional physical and chemical properties are the key to the success of the next generation of gas sensor technology, which is expected to have special features like being lightweight and flexible for wearability, mechanical robustness, reliable operation with wide environmental changes, and self-powered, in addition to the general sensor characteristics. The design of the chemiresistor with nanostructured hybrid material has indicated a great potential to meet these current demands, drawing significant attention to the technological developments in the past decades. The nanotechnology driven strategic design of the hybrid nanostructures is predicted to be pivotal for the development of nanomaterials bearing distinct physical and chemical properties and catalytic power, enabling them to produce overall improvements in sensor efficiency. In this review, a comprehensive review on the recent progress of hybrid gas sensors fabricated by coupling various metal oxides and 2D materials like transition metal dichalcogenides, graphene, and its derivatives are presented. The limitations of the current materials, key challenges, as well as the futuristic strategy for material design delivering fascinating properties and modern growth techniques are highlighted. A special emphasis has been given to hybrid sensors made with transition metal dichalcogenides, which are considered to be an emerging material and very few works have reported on its hybrid with metal oxides. The relevance of reliable detection of hydrogen is felt due to the dramatic rise in the use of hydrogen in industrial, commercial, and household purposes. As the whole world is moving toward a hydrogen economy, reliable, accurate, and robust hydrogen sensors will be a crucial component of the technological systems. In view of this, the current status and recent progress on hydrogen sensors based on heterostructured nanomaterials are also presented to the reader.