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.