One-Step Synthesis of Hollow CoS₂ Spheres Derived from Polyoxometalate-Based Metal-Organic Frameworks with Peroxidase-like Activity

In this work, hollow CoS₂ particles were prepared by a one-step sulfurization strategy using polyoxometalate-based metal-organic frameworks as the precursor. The morphology and structure of CoS₂ have been monitored by scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray powder diffraction. The mechanism for the formation of CoS₂ is discussed. The reaction time and sulfur content are found to be important factors that affect the morphology and pure phase formation of CoS₂, and a hollow semioctahedral morphology of CoS₂ with open voids was obtained when the sulfur source was twice as large as the precursor and the reaction time was 24 h. The CoS₂ (24 h) particles show an excellent peroxidase-like activity for the oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue oxidized (oxTMB) by hydrogen peroxide. The polyoxometalate used as a precursor helps to stabilize oxTMB during catalytic oxidation, forming a stable curve platform for at least 8 min. Additionally, the colorimetric detection of hydroquinone is developed with a low detection limit of 0.42 μM. This research provides a new strategy to design hollow materials with high peroxidase-mimicking activity.