Composite electrodes for electrochemical sensing: preparation and characterisation of gold nanostructures on a conductive polymeric matrix

EDUART GUTIÉRREZ-PINEDA; MARÍA J. RODRÍGUEZ PRESA; AGUSTIN E. BOLZÁN; CLAUDIO A. GERVASI

Buenos Aires

Congreso; COMAT 2015; 2015

Composite materials are very useful in the development of electrodes particularly in the field of electrocatalysis and electrochemical sensing. In the present work, composite electrodes were prepared by depositing a polypyrrole film on stainless steel substrates, onto which a random deposition of gold nanoparticles was produced. The formation of the polymer film was performed under potentiostatic conditions (0.8 V vs NHE) in different electotrolytes and growth times, in order to obtain different morphologies and film thickness. The polymeric films were characterised by different surface techniques, such as SEM, SERS, XPS and AFM. The thickness and adherence of the polymeric films depended on the electrolyte anion, as well as the resulting film morphology, i.e. worm-like or tubular surface structures were obtained. Once the morphology and structure of the films were determined, they were first electrochemically characterised by means of voltammetry and impedance measurements, and eventually decorated with gold nanoparticles by applying a double potential step routine. This routine allowed to activate the nucleation sites during a very short time and once the nuclei were formed, a second potential step allowed to growth the gold particles under controlled conditions. The presence of the gold nanostructures on the polymer film produced an enhancement of the corresponding Raman signal, and according to Raman depth measurements, the deposition of gold nanostructures occurs not only at the surface level, but also well inside the polymeric film. The feasibility of using these composite electrodes in sensing applications was checked by studying the electro-oxidation of hydrazine and hydroxilamine. In both cases, the electrodes exhibited a marked electrocatalytic activity that increased remarkably respecto to solid gold electrodes.