The main focus of the research is on chemical modification of electrode surfaces with thin films of porous inorganic solids. The objective is to use the adsorptive and catalytic properties of the solids to improve the selectivity and sensitivity of the electrodes towards solution species. Solids presently under investigation include synthetic clay minerals, layered double hydroxides (LDH) and mesoporous molecular sieves silicas.

The aim of the work on clays and LDHs is to exploit the wider range of chemical compositions of the modifiers possible with synthetic materials to improving the conductivity of the films. Natural clays and LDHs are electrical insulators. Our approach involves the introduction in the lattices of the minerals of redox active transition metal atoms. Redox active sites in the lattice of the modifiers can function as relays in the electron transfer process in the films. In some cases, this was found to result in dramatic increases in the voltammetric current obtained for species adsorbed in the modified electrodes.

The first objective of the work on mesoporous silicates is to determine if the electron transfer reactions in electrodes modified with these solids can occur deep within the mesopores. In zeolite-modified electrodes, electron transfer almost always occurs by the so-called extrazeolite mechanism, in which the electrochemical reaction takes place outside the zeolite pore system, after the electroactive species have exited the pores through ion exchanged or desorption. Similarly, in clay-modified electrodes electron transfer does not occur deep within the clay interlayer spaces. To participate in the electrochemical reaction, the adsorbed species must first diffuse out of the clay gallery spaces to the conductive substrate.

List of publications