Highly sensitive detection of ammonia gas by 3D flower-like ɤ-MnO2 nanostructure chemiresistor

Abstract

In this work, a ɤ-MnO2 flower-like nanostructure was synthesized. The structural and morphological characterization of ɤ-MnO2 flower-like nanostructure was performed by X-ray powder diffraction (XRD), N2–sorption studies (Brunauer–Emmett–Teller surface area measurements) (BET), particle size distribution (PSA), energy dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM). The ammonia gas sensor was fabricated based on the high surface area of ɤ-MnO2 flower-like nanostructure. According to the results, tetragonal tunnels were advantageous for trapping and adsorption-desorption of NH3 gas molecules. The results indicated that the gas sensor based on ɤ-MnO2 flower-like nanostructure had high sensitivity (40% response to 100 mg L−1 NH3 gas), selectivity, detectability up to 2 mg L−1 NH3 gas, long-term stability, and repeatability for two months at room temperature. Of the study also examined the effect of compounds such as ethanol, acetone, hydrazine, n-heptane, monomethylamine (MMA), triethylamine (TEA) and trimethylamine (TMA) on the detection of ammonia gas.