A bioinspired copper 2,2-bipyridyl complex immobilized MWCNT modified electrode prepared by a new strategy for elegant electrocatalytic reduction and sensing of hydrogen peroxide

Owing to facile electron-transfer reaction, metal complex based molecular architecture has attracted much interest in electrochemistry, especially for bioinspired electrocatalytic and electrochemical sensor applications. Indeed, preparation of stable surface-confined molecular system is a challenging task. In general, derivatization methodology, in which, a specific functional groups such as thiol, carboxylic acid, pyrene and amino bearing inorganic complexes synthesized discreetly by chemical approach have been attached suitably on electrode surface via any one of the following techniques; self-assembly, covalent immobilization, electrostatic interaction, ionic exchange and encapsulation. Herein, we report a copper-bipyridyl complex immobilized multiwalled carbon nanotube (MWCNT)-Nafion (Nf) modified glassy carbon electrode (GCE/Nf-MWCNT@bpy-Cu2+) prepared by a new strategy in which sequential modification of bipyridyl (bpy) ligand on MWCNT via π-π interaction followed by in-situ complexation with copper ion for efficient electrochemical reduction of H2O2. The copper species chemically modified electrode showed highly stable and well-defined surface-confined Cu2+/1+ redox peak response, without any Cu1+/0 redox transition, at an equilibrium potential, E1/2 = −135 mV vs Ag/AgCl in a pH 7 phosphate buffer solution. Detailed physico-chemical characterization by SEM, FT-IR, Raman and ESI-MS and electrochemical characterization reveals that [Cu(bpy)2(H2O)2]+ (molecular weight 413.4) like species was immobilized as a major species on the modified electrode. A bioinspired electro-catalytic reduction of H2O2 was studied using cyclic voltammetric and rotating disc electrode techniques. In further, electrochemical sensing of H2O2 by amperometric i-t and flow injection analysis methods with a detection limit values 4.5 and 0.49 μM respectively were demonstrated.