Anodically fabricated TiO2 nanopores for electrocatalytic reduction of aldehydes

Uniformly ordered titanium dioxide (TiO2) nanopores surface was synthesized by anodizing the titanium at different applied voltages 20, 30 and 40 V for 8 h in an electrolyte consisting of 0.3 wt.% NH4F and 2 vol.% H2O in ethylene glycol. The pores diameter was found to increase with applied voltage. Scanning electron microscopic studies revealed that the fabricated TiO2 nanopores have an average pore diameter of 100 nm approximately and increasing with applied voltage. X-ray diffraction, cyclic voltammetry (CV) and impedance spectroscopy studies were employed to characterize the TiO2 nanoporous film and current increase in the CV studies confirmed the increase in surface area. Electrocatalytic behavior of Ti/TiO2 nanopores was investigated for the reduction of aldehydes using cyclic voltammetry. It was observed that the nanopores catalytically reduced the benzaldehyde and furfural to corresponding alcohol. Bulk electrolysis studies were also carried out for the reduction of benzaldehyde and the product was confirmed by NMR. The two time constants in impedance study showed the involvement of pores in the reduction behavior.

► Well ordered nanostructures of titanium dioxide were fabricated by anodizing Ti surface. ► The annealed porous TiO2 film was mainly composed of anatase phase. ► Heterogeneous electrocatalytic effects have been demonstrated for the reduction of aldehydes. ► The redox couple responsible for the electrocatalytic behavior was Ti(IV)/Ti(III).