Formation of polysulfides as a smart strategy to selectively detect H2S in a Bi(iii)-based MOF material

Abstract

SU-101 was demonstrated to be an effective and efficient detector for H₂S, due to the facile generation of polysulfides, with a remarkable H₂S selectivity. Raman and XPS analyses confirmed the formation of S_n²⁻ and S₄²⁻ polysulfide species after the H₂S adsorption (at 0.05 bar, 0.1 bar and 1 bar), without compromising the structural integrity of SU-101. The detection mechanism involves rigidification of the structure by the formation of the polysulfides and blockage of the ligand–metal charge transfer (LMCT) process, which increased the radiative emission. Additionally, theoretical simulations were carried out in order to demonstrate that the interaction of the polysulfide molecules inside the pores of SU-101 is energetically stable. Remarkably, the limit of H₂S detection (LOD) was calculated to be as low as approximately 22 ppm. Finally, SU-101 is nominated as a promising candidate for implementing toxic waste valorisation (i.e., capture of toxic H₂S) toward relevant applications in accurate molecular sensing.