Au-Hg/rGO with enhanced peroxidase-like activity for sensitive colorimetric determination of H₂O₂

The Au-Hg amalgam anchored on the surface of reduced graphene oxide nanosheets (Au-Hg/rGO) has been synthesized successfully and characterized by various techniques such as transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The Au-Hg/rGO nanocomposites were found to possess excellent peroxidase-like catalytic activity and can quickly catalyze the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) to blue oxTMB in the presence of H₂O₂. The obvious color change offered accurate determination of the H₂O₂ concentration by recording the absorbance at 652 nm using a UV-vis spectrophotometer. The linear response range for H₂O₂ was from 5 μM to 100 μM and the detection limit was 3.25 μM (S/N = 3). Furthermore, a kinetic study indicated that the catalytic behavior of Au-Hg/rGO nanocomposites followed the typical Michaelis-Menten theory and Au-Hg/rGO nanocomposites showed good affinity for H₂O₂. We envision that the simple and sensitive colorimetric detection system holds great promising applications in clinical diagnostics and food and environment monitoring.