A review on p-n heterojunction based nano-composites for Gas sensing applications

Metal oxide based nanocomposite gas sensor is a device that converts the information of a gas or vapor analyte species into electrical signals using various detection principles. Change in electrical resistance/absorbance occurs when sensing material is exposed to the particular gas which is to be exposed. In order to enhance the sensitivity and selectivity of sensing material various metal dopants and different types of heterojunction can be formed with the combination of organic and inorganic materials. Due to the modification with the formation of p-n and n-n heterostructures by the inclusion of dopants and different types of nanomaterials, stability and reversibility of sensing material can be enhanced and also the response and recovery time of the material can be reduced. Surface morphology of different dimentional materials (0D, 1D, 2D, 3D etc) plays a vital role for the absorption and desorption of gas analyte. Sensing material should have large number of active sites for interaction of large analyte molecules.