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.