Reduced Graphene-Metal Phthalocyanine-Based Nanohybrids for Gas-Sensing Applications

The extraordinary mechanical, thermal, and electrical properties of a two-dimensional monolayer of graphene with a large surface area have made it a potential candidate for the detection of various explosive, combustible, and toxic gases. Yet, graphene-based sensors lack selectivity and exhibit long recovery times even at high operating temperatures. This has diverted researchers' attention to reduced graphene oxide (rGO) and its nanohybrids with different noble metals, metal oxides, organic molecules, and polymers. The nanohybrid-based sensors show improved gas selectivity and sensing characteristics, even at room temperature (RT), due to a synergistic effect on the electrical, optical, and mechanical properties of different constituents. Among various materials, metallophthalocyanine-based nanohybrids demonstrate excellent sensing at RT due to their high sensitivity, selectivity, and fast response. Further, the manipulation of the central metal ion, substitution of functional groups on the phthalocyanine ring, morphology, and operating temperature have been found to remarkably enhance the response value, selectivity, recovery, good reproducibility, and stability at RT compared with that of rGO. In this chapter, the emphasis has been made on rGO and its nanohybrids for gas-sensing applications. Different synthesis methods to prepare rGO and its nanohybrids, their gas-sensing applications, and sensing mechanisms have been discussed. This will help researchers to understand the potential of these novel materials.