Electrocatalytic Reduction of Oxalic Acid Using Different Nanostructures of Titanium Oxide

The massive production of the modern manufacturing imposes a strict control of the waste produced, in particular wastewaters. Oxalic acid is one the most renowned intermediate in wastewater treatment processes. However, it can be turned into a valuable chemical through its electro reduction to Glyoxylic and Glycolic acids as a feed stock for many chemical industries. Among the catalyst employed in catalytic wastewater decontamination, TiO₂ rises the highest attention because of its good stability to corrosion, earth abundancy, low cost, low toxicity, chemical and thermal stability. In order to select the most-performing TiO₂ nanostructure, the activity and stability towards oxalic acid electro-reduction has been analyzed by employing TiO₂ nanotubes (TNT), nano-flames structures (TNF) and commercial nanopowders (TNP). Among them, TNT showed better electrocatalytic activity, followed closely by TNF, with a current density about three times higher than TNP, as well as better selectivity. The double layer capacitance analysis shows that TNT has a peculiar structure which guarantees a higher active surface. As a final result, the impedance spectroscopy showed that both TNT and TNF electrodes exhibit lower resistance and enhanced stability and durability with respect to TNP.