Recent Advances in Porous Carbon-Based Inorganic Flexible Sensor Journey from Material Synthesis to Sensor Prototyping

Abstract

Flexible nanoelectronics is an evolving technology with new innovative horizons for aspirations of modern society. Flexible devices exhibits uniform electronic properties over a wide range of deformation, which motivated the researchers to integrate nanoelectronic devices on novel, non-planar, and bendable substrates. These exploration lead to the low cost manufacturing of devices broadly used in the field of sports, smart medical systems, human machine interface, sensing technologies, etc., with environmental friendly and recyclable substrate benefits. Tremendous amount of research and design process is being pursuit to develop sensors with miniaturized size, high precision, and reproducibility. On the basis of surface adsorbed ion and charge transfer mechanism various sensor like chemiresistors, field effect transistors (FET), schottky diodes, surface acoustic wave, impedance, and heterojunction devices are being fabricated and optimized on flexible substrates. Functionalized nanomaterials are critical for flexible gas sensor because of their extremely high electron transport property and energy efficiency. The advances in material science provided new approaches to researcher to synthesize nanostructured porous graphene and transition metal dichalcogenides (TMDs) for gas sensors. Graphene, a two-dimensional honeycomb-like nanomaterial made of sp2-hybridized carbon atoms has emerged as a highly efficient material due to its extraordinary physical and mechanical properties such as high transmittance (97.7%), high Young’s modulus (1 TPa), high specific surface area (2630 m2/g), high thermal conductivity (5000 W/m·K), high carrier mobility (2:5 × 105 cm2/V·s), ease of functionalization, compactness etc. that make it important nanomaterials for a wide range of applications in nanoelectronics, photonics, energy storage, biomedical and sensing. On the other hand TMDs also have high surface area to volume ratio similar to graphene that provides large active sites for surface adsorption of external moieties. This provides an excellent platform for the adsorbents for anchoring on the sites. In addition, TMDs bandgap can be tuned through various techniques that further provide appropriate bandgap and band alignment with its composite to make them more suitable for sensing applications. The diversified porous graphene-TMDs nanomaterial provides physicochemical properties that are very fascinating. This hybrid combination may provide more novel and improved properties by physical or chemical doping and hybridization with other functional species for achieving high-performance sensors. This chapter focuses on current research status of hybrid porous graphene/inorganic nanomaterial-based flexible gas sensors. Several syntheses, characterization, gas-sensing mechanism, device structure, performance parameter, and other perspectives are elaborately given to rationally present the complete life cycle from material synthesis to sensor prototyping.