Studies on Electrochemical Oxidation Reaction of 2,4-Dichlorophenol on Pt Electrode

Cyclic voltammetry(CV) and in situ FTIR spectrometry were employed to study the electrochemical oxidation mechanism of 2,4-dichlorophenol (2,4-DCP) in NaOH solution. Density functional theory ( DFT) was used to calculate the Fukui function for 2,4-DCP and gave the information on possible reactive sites of 2,4-DCP during electrochemical oxidation. CV results show that the Pt electrode exhibits a high electrochemical activity for the electrochemical oxidation reaction of 2,4-DCP. On the basis of in situ FTIR data, the electrochemical oxidation reaction of 2,4-DCP is as follows: (1) C-Cl band of 2,4-DCP is broken to form phenol directly; (2) C-Cl band of 2,4-DCP is broken and C-O band is formed with " OH radicals, and the Fukui function results show that 'chlorine atom at 4 position is easier to be replaced with the hydrogen or - OH radicals. Then hydroxylation reaction happens on the C4-position of phenol leading to form hydroquinone which is subsequently electrochemically oxidized to benzoquinone. With the potential increasing, aliphatic carboxylic acids are formed after the ring cleavage; (3) part of 2,4-DCP is electrochemically oxidized to chloromaleic acid directly. At about 1700 mV, CO2 could be formed during electrochemical oxidation reaction of 2,4-DCP on Pt electrode.