Unzipped catalytic activity of copper in realizing bimetallic Ag@Cu nanowires as a better amperometric H2O2 sensor

In the present work, bimetallic Ag@Cu nanowires (Ag@Cu NWs) are grown on the modified electrode's surface by seed mediated growth method. First, Ag seeds (Ag-seeds) are generated on the Nation coated glassy carbon (GC) electrode surface which in turn mediates to grow Cu shell on its surface as bimetallic Ag@Cu NWs. In the seed mediated growth approach, cetyltrimethyl ammonium bromide (CTAB) is acts as a soft template followed by stabilizing agent in controlling the size of bimetallic NWs formation. Then, the synthesized bimetallic Ag@Cu NWs on the electrode surface are characterized using SEM, XRD, ICP-AES, and electrochemical impedance spectroscopy (EIS). Finally, the electrocatalytic reduction of H2O2 is attempted in phosphate buffer (pH 7.2) using the bimetallic Ag@Cu NWs on the modified GC electrode. The bimetallic Ag@Cu NWs modified GC electrode shows an efficient electrocatalytic reduction toward H2O2 compared to bare GC and Ag-seeds decorated GC electrodes. Importantly, the increased OHads rate in H2O2 reduction plays a crucial role at the bimetallic Ag@Cu NWs modified GC electrode compared to Ag-seeds decorated GC electrode. In addition, experimentally observed voltammetric analysis indicate a negative shift in Ag-seeds decorated electrode, for the H2O2 reduction due to smaller size Ag-seeds on the electrode surface. On the other hand, an enhanced H2O2 reduction is observed with decreased overpotential due to increased surface coverage of bimetallic Ag@Cu NWs at the modified electrode. Chronoamperometry is used as a tool to study the linear correlation between 1 mM and 10 mM H2O2 and the detection limit has been achieved as 3 mu M H2O2 with the signal to noise ratio, S/N = 3 at the bimetallic Ag@Cu NWs modified GC electrode. The sensitivity of this electrode has been successfully tested in analyzing real pasteurized milk sample where H2O2 is added as a preservative in controlling the growth of microbes. (C) 2013 Elsevier Ltd. All rights reserved.