Bi₂Te₃–Au Nanocomposite Schottky Junction with Peroxidase Activity for Glucose Sensing

We report a nontransition-metal chalcogenide Bi2Te3–Aux nanocomposite (NC) architecture by two-step solvothermal synthesis of Bi2Te3 combined with in situ reduction (Kirkendall effect) of HAuCl4 (with concentration of x mM) to obtain nano Schottky junctions with Au nanoclusters on Bi2Te3 nanosheets. The interface of Bi2Te3–Au is analyzed using various microscopic, spectroscopic, and electrical characterizations. The increased Schottky junction density with increased Au loading (x = 0.25–20 mM in solution) resulted in an enhancement of peroxidase activity (POD) by 4.2–9.6 folds, upto x = 5 mM, compared to pure Au nanoclusters. The kinetics, studied by Michaelis–Menten plots, reveal similar activity of the NCs to that of the gold standard horseradish peroxidase (HRP). The binding affinities of tetramethylbenzidine for Bi2Te3–Au0.5 and Bi2Te3–Au5 are found to be 1.57 and 4.9 folds better than that of HRP. The synergistic POD activity enhancement follows the electron-transfer mechanism. A facile H2O2-mediated colorimetric glucose detection is demonstrated by the Bi2Te3–Au0.5 NCs with a limit of detection 0.38 mM. These results show the possibility of converting an inactive nontransition-metal chalcogenide to an active one with distributed nano Schottky junctions with Au nanoclusters showing synergistic POD. The nontransition-metal chalcogenide–noble metal interface may be developed for antioxidant properties, bio-detection, and bio-catalysis.