Cavity Vortex Effect: Efficient Capture, Adsorption, and SERS Detection of Dynamic Gases.

Gas is a fundamental element for sustaining life, and its types and concentrations not only reflect the functioning of the human body but also indicate environmental changes. Surface-enhanced Raman scattering (SERS) has become a popular gas detection method due to its high sensitivity and rapid response characteristics. However, in complex environments, efficiently capturing and enriching gases in the "hotspot" regions of substrates still remains a challenge. This study presents an innovative gas SERS sensor that integrates porous Ag cavity structures with zeolitic imidazolate framework-8 (ZIF-8), a type of metal-organic framework (MOF), maintaining high sensitivity and rapid detection capabilities even under varying gas flow rates. The vortex effect within the porous Ag cavities can effectively slow down the gas flow, promoting the adsorption and detection of target molecules; furthermore, the embedded ZIF-8 particles can enhance the gas molecule enrichment efficiency. Experimental results show that, at specific flow rates, the sensor achieves a detection limit of 10 ppb for 4-ethylbenzaldehyde (4-EBA), improving by an order of magnitude (100 ppb) compared to conventional convex (Ag/ZIF-8) structures. What's more, the multifunctional regions can be achieved facilely on the proposed sensor, supporting the diversified detection of different gases and offering new insights for the development of high-performance gas monitoring technologies.