Rapid and reversible detection of trace amounts of H2S in air and packaged food using a biogenic bismuth oxide nanorod colorimetric sensor

Abstract

A colorimetric reversible sensor has been developed for detection of trace amount of H2S gas in air and sealed meat packages. The active sensing area includes high surface area bismuth oxide (Bi2O3) nanorod prepared by green synthesis method. The as fabricated sensor demonstrates a rapid response in just 25 s for sensing 1 ppm H2S gas with distinct colour change in the active sensing area from white to brown. Sensing pellets were used to optimize the performance of the H2S sensor in terms of sensitivity and selectivity in air. Flexible nitrocellulose membrane filter papers coated with Bi2O3 were used to detect spoilage in packaged raw animal food products such as meat, poultry and fish. The sensor is reversible and can be recovered within a short cycle (3 min) of heat treatment at 300 °C. X-ray diffraction, Raman spectroscopy and band gap measurements confirmed partial conversion of Bi2O3 nanorods into Bi2S3 when exposed in the range of 1–100 ppm H2S gas.