Ag functionalized CuO nanograins for highly selective and sensitive ethanol detection

Abstract

Metal oxide semiconductors-based sensors are considered the strongest candidates for gas/vapour detection due to their high sensitivity, miniaturization, and durability. However, the sensor lacks the ability to selectively detect specific gases, limiting its practical applications. The functionalization of sensing element surfaces with noble metal nanoparticles (e.g., Pt, Au, and Ag) can enhance their selectivity. Herein, CuO nanograins were deposited onto the glass substrate using spray pyrolysis and Ag decorated with thermal evaporation technique. Structural studies revealed the polycrystalline nature and pure formation of CuO nanograins, as confirmed by compositional analyses. The uniform distribution of Ag/CuO nanograins and the material porosity, which are highly essential for gas sensing applications, were also verified. After being exposed to various vapours, the prepared sensing element responded better to ethanol at an operative temperature of 350 °C. For 100 ppm of ethanol, a response time of 10 s and a recovery time of 11 s was noted. It was observed that Ag/CuO shows a better selective response to ethanol than CuO in a mixed vapour environment due to catalytic action. Compared to the bare material, Ag decorated CuO showed a quick response towards ethanol.