Fabrication of Ag nanoparticles coupled with ferrous disulfide biocatalyst as a peroxidase mimic for sensitive electrochemical and colorimetric dual-mode biosensing of H₂O₂

Ag nanoparticles (Ag NPs) with high electrocatalytic activity are of great significance for electrochemical sensors. Nanostructures as scaffold can solve aggregation problem of Ag NPs so that to ensure the stability. In this work, Ag NPs immobilized on FeS₂ nanoprisms (Ag/FeS₂) were prepared via an in-situ photocatalytic reduction approach. The enlarged electrode effective surface area, enhanced electron transfer and the synergic impact between Ag NPs and FeS₂ lead to an enhanced catalytic activity. The electrochemical detection method exhibited great performance of low detection limit (0.6 μM), wide linear range and high sensitivity (244.4 μA mM⁻¹ cm⁻²) for H₂O₂. Moreover, Ag/FeS₂ as a peroxidase mimic can catalyze oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue product (oxTMB) by H₂O₂, which achieved effective detection of H₂O₂ with a 3.0 μM detection limit. A promising way was successfully eatablished to perform the quantitation of H₂O₂ in serum and beverage.