Interlinked Polyaniline/ZnO Nanorod Composite for Selective NO<sub>2</sub> Gas Sensing at Room Temperature
Thangapandian Murugesan, Rishi Ranjan Kumar, Aswin kumar Anbalagan, Chih‐Hao Lee, Heh‐Nan Lin
Abstract
Chemiresistive gas sensing has attracted extensive research attention in recent years, and the facile low-cost synthesis of sensitive materials is important for realizing practical use. One feasible approach is to create a gas-sensing nanocomposite network by infusing an easily processable conducting polymer into a solution-grown interlinking metal oxide nanomaterial. In this work, a polyaniline (PANi) and ZnO nanorod (NR) composite is synthesized for selective UV-activated NO2 gas sensing at room temperature. The nanocomposite comprises interlinking ZnO NRs that are partially covered by PANi, thus forming a charge transport network with abundant gas adsorption sites. Uniform and interlinking ZnO NRs are grown on a prepatterned silicon substrate by using a hydrothermal method, and PANi is prepared by using an in situ oxidative polymerization method. A PANi/ZnO 0.5 nanocomposite with uniform morphology is obtained by drop-casting a PANi solution on the ZnO NRs. The nanocomposite exhibits selective NO2 gas toward various gases including CH2O, NO, and NH3. The responses are 130% and 20920% for 0.05 and 2.5 ppm NO2, respectively. The low-concentration linear sensitivity is 11.7% ppb–1. Based on the Langmuir adsorption model, the adsorption and the desorption constants are determined to be 7.65 × 10–3 ppm–1 s–1 and 1.07 × 10–2 s–1, respectively. The excellent gas-sensing performance of the PANi/ZnO 0.5 nanocomposite is attributed to the formation of abundant p–n heterojunction adsorption sites.