Localized surface plasmon resonance sensing of SO2 and H2S using zeolitic imidazolate framework-8

A localized surface plasmon resonance (LSPR) sensor for SO2 and H2S has been developed by coating a Au nanopattern with zeolitic imidazolate framework-8 (ZIF-8), which is one of the most common metal-organic frameworks. SO2 and H2S were detected by the change in the absorbance at a certain wavelength in the LSPR spectrum. The sensitivity to SO2 and H2S was enhanced by ZIF-8 and with increasing relative humidity, and 0.1-20 ppm SO2 and 0.1-10 ppm H2S could be detected within 5 min at 70% relative humidity. The ZIF-8-coated sensor was more sensitive to SO2. The changes in the absorbance increased during exposure to SO2 and H2S, and only slightly decreased for SO2 and remained almost constant for H2S after stopping exposure. These responses indicate that the sensor can measure the integrated concentrations of SO2 and H2S. If the sensor was not exposed to >= 20 ppm SO2 or >= 10 ppm H2S, the sensitivity and LSPR spectrum of the sensor could be recovered approximately a dozen times by heating it at 200 degrees C in air. This study demonstrates the potential of metal --organic-framework-coated LSPR sensors for highly sensitive detection of SO2 and H2S.