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

• Published in: Electrochimica acta 2013-12, Vol.112, p.648-654
• Main Authors: Easow, Jeena Susan, Selvaraju, T.
• Format: Article
• Language: English
• Subjects: Ag@Cu nanowires; Autocatalysis; Hydrogen peroxide sensor; Modified electrode; Pasteurized milk sample; Seed mediated growth approach
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2013.09.033

Schematic representation of the electroreduction of H2O2 at GC/Nf/Agseeds electrode (A) and at bimetallic GC/Nf/Ag@Cu NWs electrode (B). 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 (Agseeds) are generated on the Nafion 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 Agseeds 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 Agseeds decorated GC electrode. In addition, experimentally observed voltammetric analysis indicate a negative shift in Agseeds decorated electrode, for the H2O2 reduction due to smaller size Agseeds 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 1mM and 10mM H2O2 and the detection limit has been achieved as 3μM 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.