A novel, effective and low cost catalyst for formaldehyde electrooxidation based on nickel ions dispersed onto chitosan-modified carbon paste electrode for fuel cell

In this study, a novel modified carbon paste electrode (CPE) was fabricated by chitosan and then Ni2+ ions incorporated to this electrode by immersion of the modified electrode in a 0.5 M nickel chloride solution. The values of charge-transfer rate constant and electrode surface coverage for Ni(II)/Ni(III) redox couple and redox sites of modified carbon paste electrode (Ni-CHIT/CPE) were found to be 0.174 s(-1) and 7.38 x 10(-8) mol cm(-2), respectively. The electrochemical behavior of the Ni-CHIT/CPE electrode towards oxidation of formaldehyde was evaluated by cyclic voltammetry technique as well as chronoamperometry method. It has been observed that chitosan at the surface of CPE can improve catalytic efficiency of the dispersed nickel ions toward oxidation of formaldehyde. The values of electron transfer coefficient, diffusion coefficient and the mean value of catalytic rate constant for formaldehyde and redox sites were obtained to be 0.47, 2.68 x 10(-6) cm(2) s(-1) and 2.06 x 10(5) cm(3) mol(-1) s(-1), respectively. Obtained results from cyclic voltammetry and chronoamperometric techniques specified that the electrode reaction is a diffusion-controlled process. The good catalytic activity, high sensitivity, good stability and easy in preparation rendered the Ni-CHIT/CPE to be a capable electrode for electrooxidation of formaldehyde.