In recent years, gas sensors are playing a very prominent role in energy consumption, natural observation, and monitoring of air and gas quality, especially in the detection of explosions and dangerous gases. These sensors are attracted keenly by researchers to get rid of air pollution and security issues in the world. There are several techniques being used to sense gases such as gas chromatography, FTIR, mass spectrometer, semiconductor gas sensor, and so on. Among all, gas sensors based on semiconducting materials provide excellent gas sensing efficiency than gas detecting methods....