Carbon dioxide gas detection by open metal site metal organic frameworks and surface functionalized metal organic frameworks

Novel nanoporous materials known as Metal-Organic Frameworks (MOFs) are currently attracting wide attention due to their potential applications such as gas storage, gas separation and catalysis. Recently, MOF materials were also developed for chemical sensors. In this work, for the first time iso-structural MOFs M-MOF-74 (where M = Mg, Ni, Co and Zn) and ethylenediamine functionalized Mg-MOF-74 were investigated as selective CO2 gas sensing material for the work function read-out based method at ambient temperature and different humidity levels. M-MOF-74s are very interesting MOFs because they contain coordinatively unsaturated metal centers where adsorbates can interact strongly with their affinity towards gas molecules. Interaction of the CO2 molecules with open metal sites or amine-functional groups changes the work function (ΔΦ) of sensing layer which can serve as a signal for gas sensors. Results show that ethylenediamine functionalized Mg-MOF-74 exhibited enhanced CO2 gas sensing properties compared to other M-MOF-74 with respect to sensitivity, reversibility and stability.