Selective Electroreduction of Oxalic Acid to Glycolic Acid by Mesoporous TiO2 Spheres

Reducing oxalic acid to glycolic acid electrochemically remains a significant challenge due to the high overpotential and low selectivity and stability. This study uses mesoporous TiO2 spheres of anatase phase as catalysts to reduce oxalic acid to glycolic acid with low overpotential. The maximum Faradaic efficiency of glycolic acid reaches 73.9 % at -0.5 V vs RHE. The mesoporous structure not only increases the specific surface area, but also limits the escape of intermediate glyoxalic acid from the catalyst surface due to the space-limiting effect of the mesoporous channel, such that oxalic acid can be deeply reduced to glycolic acid. Moreover, a mechanism for oxalic acid reduction is proposed, and the Ti3+/Ti4+ redox pair plays an important role in the reduction of oxalic acid.

Automated summary

Reducing oxalic acid to glycolic acid electrochemically is difficult due to high overpotential, low selectivity, and low stability. This study presents mesoporous TiO2 spheres as catalysts for the reduction of oxalic acid to glycolic acid at low overpotential. The mesoporous structure increases the specific surface area and restricts the escape of intermediate glyoxalic acid, enabling deep reduction of oxalic acid to glycolic acid. The proposed mechanism suggests the important role of the Ti3+/Ti4+ redox pair in the reduction of oxalic acid.