Fast response paper based visual color change gas sensor for efficient ammonia detection at room temperature

Abstract

Abstract We show that a cheap, disposable type rapid paper sensor (working at room temperature) can be made using perovskite halide CH 3 NH 3 PbI 3 (MAPI) to detect presence of the toxic ammonia gas (NH 3 )by just color change, where the black colored MAPI film (on the paper) changes to yellow color in presence of a very low concentration of NH 3 gas. The sensor can detect presence of NH 3 gas in open or closed atmosphere down to around 10 ppm with a response time of nearly 10 sec which decreases to few seconds when the concentration exceeds 20 ppm. The easy to fabricate sensor paper being a visual sensor does not need any other extra equipment for its operation. The sensor is not sensitive to moisture with RH upto 90% and does not also respond to gases like Methane (CH 4 ), Nitrous Oxide (N 2 O), Carbon dioxide (CO 2 ) etc in the test chamber each up to a concentration of 500 ppm. Conversion/decomposition of MAPI to PbI 2 on exposure to NH 3 has been proposed as the mechanism of color change and the mechanism has been established using a collection of techniques like XRD, EDX, UV-Visible absorption and Photo Luminescence.