Sensing of Hydrogen Sulfide Gas in the Raman-Silent Region Based on Gold Nano-Bipyramids (Au NBPs) Encapsulated by Zeolitic Imidazolate Framework-8.

Mostly, surface-enhanced Raman scattering (SERS) sensors used the Raman characteristic bands concentrated in the Raman "fingerprint" region (500-1800 cm-1), which may result in spectral overlapping interference. The study of the response in the Raman-silent region (10-500 and 1800-2800 cm-1) can help overcome this problem. Hydrogen sulfide (H2S) gas causes a great threat to human's health, but its low concentration in the airborne species is a challenge for sensitive and selective detection. Herein, a novel low-wavenumber (10-500 cm-1) SERS sensor for H2S gas detection has been developed based on gold nano-bipyramids (Au NBPs) encapsulated by zeolitic imidazolate framework-8 (ZIF-8) (Au NBPs@ZIF-8). The sensor takes advantage of the high adsorption capacity of ZIF-8 toward H2S gas and the H2S-triggered SERS spectral changes in the low-wavenumber Raman-silent region. A clear SERS peak of Au-Br at ∼175 cm-1 generated from Au NBPs@ZIF-8 showed a decrease in the presence of H2S because of the competition of adsorption sites between Au-S and Au-Br bonds. Furthermore, Au NBPs@ZIF-8 can enrich and monitor the level of H2S gas with high efficiency and low interference. The developed sensor has a detection range of 0.2 nM to 20 mM with a limit of detection (LOD) of 0.17 nM. The developed sensor had been applied to detect the H2S gas released from the spoiled fish meat with high selectivity.