Synergistic effect of gold nanoparticles and amine functionalized cobalt porphyrin on electrochemical oxidation of hydrazine

Abstract

This paper describes the immobilization of citrate capped gold nanoparticles (cit-AuNPs) on indium tin oxide (ITO) and glassy carbon electrode (GCE) surfaces using a electroactive linker, meso-tetra(para-aminophenyl)porphyrinatocobalt(II) Co(II)MTpAP. The immobilization of cit-AuNPs on Co(II)MTpAP was achieved with the aid of amine groups present on the self-assembled monolayer (SAM) of Co(II)MTpAP. This was confirmed by UV-vis, atomic force microscopy (AFM), cyclic voltammetry, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques. The particle coverage estimated from AFM was found to be ∼65% which is higher than the previously reported linkers used for immobilization. The AFM image shows that the cit-AuNPs were densely packed on Co(II)MTpAP. Furthermore, the electrocatalytic activity of the AuNP modified electrode was examined by studying the oxidation of hydrazine. Interestingly, the cit-AuNPs immobilized on Co(II)MTpAP showed a greater catalytic effect towards hydrazine oxidation than cit-AuNPs immobilized on free base porphyrin. This was attributed to the synergistic effect arising from both AuNPs and Co(II).