engleski

Indium as a cathodic material: catalytic reduction of formaldehyde

The performance of indium, as cathodic material for electroreduction of small organic molecules were studied. The cathodic reduction of formaldehyde (FA) is an ideal model reaction for this purpose since indium has very large overpotential for the hydrogen evolution reaction with and without FA. Kinetic sets of the reaction pathways, with respect to the Tafel slope and reaction order, are considered on the basis of quasi-potentiostatic measurements and cyclic voltammetry. The value of the Tafel slope bc=60 mVdec-1 indicates that protonation of the adsorbed radical is the rate determining step in the proposed CECE mechanism. The reaction order with respect to FA is close to one in the limiting current regions, but smaller in the Tafel region. The existence and kinetics of the radicals adsorbed during FA reduction are evidenced by very fast potentiodynamic experiments, with scan rate between 40 and 80 Vs-1. Electrochemical measurements are carried out on freshly in-situ prepared In-electrodes. During cathodic polarization the surface oxide film is reduced to In-metal via a solid-state mechanism. The crystallization kinetics of indium in the oxide matrix is also discussed

electrocatalysis ; electroreduction ; cathodic material ; indium ; formaldehyde

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