Ag/ZnO Nanocomposite-Decorated Capillary for Rapid Trace Gas Identification Based on Surface-Enhanced Raman Scattering under Ambient Conditions

Rapid trace gas identification is challenging due to the low adsorptivity of gaseous molecules on solid substrates under ambient conditions. In this article, we present a gas sensor utilizing a capillary serving as a surface-enhanced Raman scattering (SERS) probe. The capillary is decorated with densely distributed Ag/ZnO nanocomposites within its microchannel, resulting in an enlarged specific surface area that enhances gas adsorption and chemical enhancement and provides abundant SERS hotspots. The introduction of gas into the capillary leads to the immediate appearance of distinctive Raman characteristic peaks, and the entire measurement process can be performed under ambient conditions. The detection limit for gases of NO2 and SO2 reaches as low as 0.1 ppb. Furthermore, the sensor exhibits the capability to identify components of mixed gases as well as effectively detect NO2 in vehicle exhaust emissions. With all of these advantages, the SERS-active capillary demonstrates promising potential for practical applications, particularly in the rapid and accurate identification of trace-level gases.