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.