CuO induced Au nanochains for highly sensitive dual-mode detection of hydrogen sulfide.

Colorimetric and chemoresistive gas sensing methods have aroused great interest in HS monitoring due to their unique merits of naked-eye readout, and highly sensitive and rapid detection. However, combining these two methods for gas detection, especially utilizing one material as their common sensing material is a grand challenge because they are inconsistent in sensing mechanism. Taking advantage of the strong chemical affinity of CuO for HS and the excellent performance of localized surface plasmon resonance (LSPR) of Au nanoparticles (NPs) in the visible regions and its ability as a noble metal to enhance gas sensing property, the CuO-Au nanochains (NCs) were prepared for dual-mode detection of HS gas. The CuO-Au chemoresistive gas sensor shows a 5-fold higher response than CuO sensor at room temperature with a low detection limit of 10 ppb. Such good performance is attributed to the spillover effect and catalytic activity of Au NPs, and the enhanced HS adsorption after Au loading as revealed by density functional theory calculation. Test strips containing CuO-Au produced for gaseous HS detection show superior color gradient changes (blue, yellow, and brown). Finally, the practicability of the method was validated by real-time monitoring HS released from cell culture.