Study of the electrochemical oxidation mechanism of formaldehyde on gold electrode in alkaline solution

The oxidation of formaldehyde in alkaline solution was studied by in situ rapid-scan time-resolved IR spectroelectrochemistry (RS-TR-FTIRS) method. In the potential range between −0.7 V and 0.2 V, the gem-diol anions were oxidized (according to the 2765 cm⁻¹ of υ_HO and 1034 cm⁻¹ of υ_CO downward IR bands) and the formate ions appeared (according to the 1588, 1357 cm⁻¹ of the asymmetric and symmetric υ_OCO and 1380 cm⁻¹ of δ_CH upward IR bands) in aqueous solution. It was also confirmed that gem-diol anion was oxidized (according to the 2026, 1034 cm⁻¹ downward IR bands) to formate ions (according to the 1595, 1357, 1380 cm⁻¹ upward IR bands) and water (according to the 3427 cm⁻¹ of υ_HO upward IR band) in heavy water solution. The results illustrated that formaldehyde formed gem-diol anion in alkaline solution and was absorbed on the electrode surface; then gem-diol anion was oxidized to formate ions and water.