Facile growth of Ag@Pt bimetallic nanorods on electrochemically reduced graphene oxide for an enhanced electrooxidation of hydrazine

Abstract

An efficient transducer was constructed by the direct growth of bimetallic Ag@Pt nanorods (NRDs) on L−tryptophan functionalized electrochemically reduced graphene oxide (L−ERGO) modified electrode using galvanic displacement method for the electrooxidation of hydrazine. Initially, one dimensional bimetallic Ag@Cu core−shell NRDs were grown on L−ERGO modified electrode by simple seed mediated growth method. Then, the Cu shells at bimetallic NRDs were exchanged by Pt through galvanic displacement method. Accordingly, the synergetic effect produced by the combination of Ag and Pt as NRDs at L−ERGO surface enabled an enhancement in the electrocatalytic efficiency for hydrazine oxidation. L−ERGO supported bimetallic Ag@Pt NRDs were characterised by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and cyclic voltammetric techniques. Finally, the modified electrode was successfully used for the electrooxidation of hydrazine in PB (pH 7.4) with a detection limit of 6 × 10⁻⁷ M (S/N =3). Importantly, the presence of Pt on Ag surface plays a vital role in the electrooxidation of N₂H₄ at −0.2 V with an onset potential at −0.5 V where its overpotential has decreased. On the other hand, L−ERGO nanosheets tend to facilitate an effective immobilization of low density Ag seeds (Ag_seeds) on its surface. Chronoamperometric studies were used to study the linear correlation of [N₂H₄] between 1 mM and 10 mM. The modified electrode shows a high sensitivity and selectivity for a trace amount of N₂H₄ in the presence of different interfering cations and anions.