Cu-MOF-808 as a Sensing Material for Gaseous Hydrogen Sulfide

The selective detection of hydrogen sulfide (H₂ S) is an important task because of its potentially hazardous effects not only on the environment but also on human health. Here, we present the zirconium-based MOF-808, which was modified with copper salts, as a colorimetric sensor material for the visible, reversible and sensitive H₂ S detection at room temperature. The copper cations, which are incorporated in the oxidation state +II, are installed at the inorganic building units (IBUs) of the framework so that they are accessible for interactions with H₂ S. The activated copper doped MOF-808 powder shows significant and fast color change in the presence of H₂ S, which can be detected by UV-vis spectroscopy. Moreover, the detection process is reversible by heating the material to 120 °C under ambient conditions leading to its decolorization. The detection performance of the material was studied by in situ UV-vis measurements in a reaction chamber. The material was able to respond to 100 ppm H₂ S in several cycles of exposure and heating to 120 °C under moist air conditions in a defined wavelength range. This reversibility is very uncommon for copper-based H₂ S sensing reactions and highlights the potential of MOFs as selective sensing materials.