Manufacture and evaluation of carbon nanotube modified screen-printed electrodes as electrochemical tools.

Carboxylated multiwalled carbon nanotubes (MWCNT-COOH) dissolved in a mixture of DMF:water were used to modify the surfaces of commercially available screen-printed electrodes (SPEs). The morphology of the MWCNT-COOH and the modified SPEs was characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. SEM analysis showed a porous structure formed by a film of disordered nanotubes on the surface of the working electrode. The modification procedure with MWCNT-COOH was optimised and it was applied to unify the electrochemical behaviour of different gold and carbon SPEs by using p-aminophenol as the benchmark redox system. The analytical advantages of the MWCNT-COOH-modified SPEs as voltammetric and amperometric detectors as well as their catalytic properties were discussed through the analysis, for instance, of dopamine and hydrogen peroxide. Experimental results show that the electrochemical active area of the nanotube-modified electrode increased around 50%. The repeatability of the modification methodology is around 6% (R.S.D.) and the stability of MWCNT-COOH-modified SPEs is ensured for, at least, 2 months.