Pore-confined cobalt sulphide nanoparticles in a metal–organic framework as a catalyst for the colorimetric detection of hydrogen peroxide

Abstract

In this study, nanoparticles of cobalt sulphide solely confined within the nanopores of a water-stable zirconium-based metal–organic framework (MOF), MOF-808, are synthesized by a two-step approach, with the first step being installing spatially dispersed cobalt ions within the entire framework of MOF-808 and the second step being solution-phase sulphurisation. The crystallinity, morphology, porosity, and loading of cobalt sulphide in the obtained nanocomposite are investigated. As a demonstration, the obtained nanocomposite is used as a heterogeneous catalyst for the redox reaction between 3,3′,5,5′-tetramethylbenzidine (TMB) and H₂O₂ in aqueous acetate buffer solutions. The pore-confined cobalt sulphide nanoparticles show remarkable catalytic activity, and the catalysis has typical Michaelis–Menten kinetics. Relying on the optical change that originated from the generation of oxidized TMB, as a demonstration, the nanocomposite can be utilized in the colorimetric quantification of H₂O₂.