Cu‐MOF‐74 as Fluorescent Probe: Selective Optical Sensor for H2S Gas

In order to address the air quality issues and industrial gas leakages effectively, gas sensors must be highly sensitive, selective, stable, cost‐effective, and with high life time. We present here a facile solvothermal method to synthesize a Cu based metal‐organic framework (Cu‐MOF‐74) and demonstrated its potential as a selective fluorescent probe for environmental H2S gas detection. Cu‐MOF‐74 based fluorescence sensor shows strong affinity towards H2S with the limit of detection as low as 7 ppm. Impressively, though Cu‐MOF‐74 based sensor exhibited high sensitivity and selectivity for H2S gas over H2, SO2 and NH3, Co‐MOF‐74 is inactive towards H2S sensing. The increased fluorescence intensity in presence of H2S gas as well as the decreased fluorescence intensity in presence of NO2 gas was investigated by experimental observation and theoretical calculation. In presence of H2S gas, interaction between Cu and sulphur atoms occur, which weaken the bond between Cu and ligand which in turn reduces the extent of ligand to metal charge transfer, resulting in increase in fluorescence intensity. The present attempt led to the progress of highly selective and sensitive fluorescence based environmental gas sensing probe using metal organic framework within a wide operating temperature ranging of 25 °C to 90 °C.