Sunmi Im  Yiseul Park

Vol. 30,  No. 4, pp. 306-313, Dec.  2024
10.7464/ksct.2024.30.4.306

TiO2 nanotube Metal treatment Oxalic acid Glycolic acid Electrochemical conversion

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Oxalic acid can be converted into glycolic acid through an electrochemical reduction reaction. Among the various materials studied for this purpose, TiO2 nanotube (TNT) electrodes are advantageous due to their eco-friendly properties and tubular structure, which facilitates a continuous two-electron reduction reaction and leads to a high selectivity for glycolic acid. However, the conversion rate of oxalic acid remains at only 40 ~ 50%. This study aimed to enhance the electrochemical properties of TNT by treating it with various metals to improve the conversion rate of oxalic acid. Compared to the conventional TNT used for the electrochemical conversion of oxalic acid, the metal-treated TNT showed significant differences in structure, conversion rates, and faradaic efficiency depending on the type of metal used. When Pt and Co were treated onto TNT, only the water reduction reaction occurred, and there was no reduction of oxalic acid. On the other hand, when W and Zn were treated onto TNT, the conversion rate of oxalic acid improved compared to the untreated TNT. However, the faradaic efficiency was slightly lower than that of the untreated TNT. This resulted from an increase in both oxalic acid and water reduction efficiencies due to the enhanced electrical conductivity of the TNT electrode caused by the doped ions. In the case of Cr-treated TNT, the nanotube structure was not formed and a non-porous electrode was formed. This led to a significant reduction in the surface area and a sharp decline in the conversion rate of oxalic acid.