Thin films of α-Mn 2 O 3 for resistance-based sensing of acetaldehyde vapor at ambient temperature

Thin films of dimanganese trioxide (α-Mn 2 O 3 ) were deposited on glass substrates by using manganese acetate tetrahydrate as the precursor salt and spray pyrolysis technique. X-ray diffraction patterns of the film indicate a polycrystalline nature and a cubic crystal structure. Field-emission scanning electron micrograph and transmission electron micrograph reveals the formation of spherical nanocrystallites along with pores with sizes of 10 ± 5 nm. The electrical resistance of the film drops on exposure to vapours of acetaldehyde at ~30 °C. The sensor covers the 5 to 75 ppm concentration range, displays fast response (9 s) and recovery (~35 s), and is fairly selective over acetone, ammonia, formaldehyde, benzene, water vapour and ethanol. Graphical Abstract Thin films of manganese(III) oxide are shown to enable resistance based sensing of acetaldehyde. Graph (a) shows a transmission electron micrograph of a spray-deposited film of α-Mn 2 O 3 ; (b) gives the response to various concentrations of acetaldehyde at around 30 °C; and (c) shows the spray deposited sensor film on a TO-6 pin header