Pt74Ag26 nanoparticle-decorated ultrathin MoS2 nanosheets as novel peroxidase mimics for highly selective colorimetric detection of H2O2 and glucose

Abstract

To extend the functionalities of two-dimensional graphene-like layered compounds as versatile materials, the modification of transition metal dichalcogenide nanosheets such as MoS₂ with metal nanoparticles is of great and widespread interest. However, few studies are available on the preparation of bimetallic nanoparticles supported on MoS₂. Herein, a facile and efficient method to synthesize MoS₂–PtAg nanohybrids by decorating ultrathin MoS₂ nanosheets with octahedral Pt₇₄Ag₂₆ alloy nanoparticles has been reported. The as-prepared MoS₂–Pt₇₄Ag₂₆ nanohybrids were investigated as novel peroxidase mimics to catalyze the oxidation of classical peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H₂O₂, producing a blue colored reaction and exhibiting typical Michaelis–Menten kinetics. MoS₂–Pt₇₄Ag₂₆ has a higher affinity for H₂O₂ than horseradish peroxidase (HRP) and a higher v_max value with TMB as the substrate than MoS₂. The improved catalytic activity of hybrids for colorimetric reactions could be attributed to the synergistic effects of octahedral Pt₇₄Ag₂₆ nanoparticles and ultrathin MoS₂ nanosheets as supports. Meanwhile, the generation of active oxygen species (˙OH) by H₂O₂ decomposition with MoS₂–Pt₇₄Ag₂₆ was responsible for the oxidation of TMB. On the basis of these findings, a colorimetric method based on MoS₂–Pt₇₄Ag₂₆ nanohybrids that is highly sensitive and selective was developed for glucose detection. Lower values of the limit of detection (LOD) were obtained, which is more sensitive than MoS₂ nanosheets.