Electrocatalysis of the quinone/hydroquinone system by electrodes coated with substituted polyaniline

Abstract
Polymer films derived from N‐methylaniline (NMA), N(3‐sulphopropyl)‐aniline (NSPA), 2‐ and 3‐methylanilines (2‐MA and 3‐MA), and 2,3‐, 2,5‐ and 2,6‐dimethylanilines (2,3‐DMA, 2,5‐DMA and 2,6‐DMA), as well as of some copolymers, were obtained on a platinum electrode in acidic solution by potential cycling. Electrocatalytic properties of the resulting polymer coated electrodes towards the hydroquinone‐benzoquinone redox couple were investigated. The following sequence of catalytic activity was found: poly(2‐MA)>polyNMA = copoly (2‐MA+3‐MA) > copoly(NMA+NSPA) > polyNSPA>poly(3‐MA). With respect to the stability of catalytic effects observed at prolonged potential cycling, the following sequence can be drawn: poly(2‐MA) > polyNSPA≫copoly(2‐MA+3‐MA) = poly(3‐MA) > copoly(NMA+NSPA) > polyNMA. Thus, poly(2‐MA) was found to be the most effective and stable electrocatalyst in the redox couple investigated. The polymers derived from dimethylanilines were found to inhibit this redox process.

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