Effect of porosity on the electroanalytical performances of modified electrodes

In the last years, the use of polymer films and/or the employment of layers of carbon nanotubes (CNTs) to build “chemically modified electrodes” to be used in the electroanalytical field are spreading. The reason is that the final devices present better performances, particularly in terms of peak current increments and of voltammetric peak separation narrowing, useful features for increasing selectivity and sensitivity and lowering detection limits. Recently, it has been proposed that the better performances are not only due to a change in electrode kinetics (e.g. catalytic effects brought by nanomaterials or their functionalization, decrease in charge transfer resistance) or to an increment of surface area or porosity distribution, but also by a change in the diffusion mechanism, from linear to thin-layer or convergent [1-2]. In this presentation, we would like to contribute to this debated topic, with some experimental results obtained working with electrodes modified with appropriately functionalized CNTs and with electrodes modified with Sulphonated Poly (Aryl Ether Sulphones), a new class of polymers, ad hoc tailored for our electroanalytical applications. These modifications have led to an increase in the mesoporosity which, according to us, is the responsible of the transition from the linear diffusion regime to the thin layer behavior, causing the enhancement of the peak currents. Applications of the optimized devices to the detection of some contaminants of emerging concern (e.g. benzidines) will be also presented. [1] I. Streeter, R. Baron and R.G. Compton J. Phys. Chem. C, 2007, 111, 17008–17014. [2] M.C. Henstridge, E. J. F. Dickinson, M. Aslanoglu, C. Batchelor-McAuley and R.G. Compton Sensors Actuators B Chem., 2010, 145, 417–427.