Luminescent metal-organic framework-based dosimeter for H2S gas detection

Abstract

Hydrogen sulphide (H₂S) is considered toxic even at low levels (with concentrations immediately dangerous to life and health (IDLH) of 100 ppm). Intriguingly, the presence of a very low level of H₂S gas (∼0.5 ppm) in the air can be detected by humans due to its characteristic pungent smell. However, upon constant exposure to H₂S, the sense of smell gets dissipated due to olfactory paralysis, resulting in a false sense of safety and consequently leading to fatal conditions. Recently, luminescent metal organic frameworks (LMOFs) have emerged as novel platforms for gas sensing applications due to their superior optical properties and high porosity. In the current work, we report the fabrication and sensing behaviour of a LMOF coated fibre-optic sensor probe for highly sensitive and real-time detection of hydrogen sulphide gas under ambient conditions. The sensor probe was fabricated by functionalising the end tip of a silica-based optical fibre with silver-based LMOF. The constituent silver ions of LMOF not only provided reactive sites for H₂S gas, but the resulting interaction also offers a highly sensitive photoluminescence quenching-based sensing mechanism for sustained detection of H₂S. Additionally, we also deduced that the integration method of LMOF has a marked effect on the overall sensing performance. The sensor probe can detect H₂S in real time with a lower limit of detection at 0.085 ppm.