Preparação e caracterização do nanocompósito baseado em óxido de grafeno reduzido/hexacianoferrato de óxido de rutênio e aplicação como sensor eletroquímico

Abstract

The preparation of a nanocomposite based on reduced graphene oxide and ruthenium oxide hexacyanoferrate (rGO/RuOHCF) nanoparticles was performed by cyclic voltammetry. Control-materials were prepared analogously for comparison. Electrochemical tests revealed a synergic effect between the rGO sheets and RuOHCF nanoparticles due to current intensity increasing and higher stability during 50 voltammetric scans comparing to RuOHCF film. The results were more pronounced in acidic media (pH= 1.5), which was used for the rest of the work. Raman and infrared spectroscopy were performed and revealed the effective reduction of GO and the hexacyanoferrate formation. The scanning electron microscopy (SEM) showed RuOHCF nanoparticles of approximately 89 nm distributed over rGO sheets and the expected elements were identified by energy dispersive X-ray spectroscopy (EDS). The electrochemical oxidation processes of ranitidine (RTD) and ethanol (EtOH) were analyzed using the rGO/RuOHCF electrode. The scan rate tests revealed that ranitidine's electroxidation is controlled by adsorption and EtOH's by diffusion. The standard analytes were used to voltammetric determination and showed high linear correlation (R 2 = 0.999) in a concentration range of 20 to 150 µmol L-1 for ranitidine and 2.5 to 150 mmol L-1 for ethanol. The amperometric determination coupled to batch-injection analysis (BIA) provided the determination of those molecule in commercial samples. RTD was successfully detected (95.8 and 95.5%) in two different brand of medicines, and EtOH was recovered in 104.4% in commercial alcohol sample and 101.8% in cachaça sample. Thereby, the rGO/RuOHCF nanocomposite synthesized exclusively by an electrochemical route showed a promising electroanalytical sensor for different molecules.