Improved catalytic performance of Pt/TiO2 nanotubes electrode for ammonia oxidation under UV-light illumination

An improved catalytic performance of Pt/TiO2 nanotubes for ammonia oxidation under UV illumination was reported for the first time. Flower-like Pt particles consisting of many Pt nanosheets were electrodeposited on TiO2 nanotubes grown on a Ti foil. The surface morphology and composition of the prepared Pt/TiO2 nanotubes were investigated by the scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The electrochemical behaviour of the prepared Pt/TiO2 nanotubes electrode for the ammonia oxidation was investigated with or without UV illumination. The results showed that the Pt deposits have a face-centered cubic structure and TiO2 nanotubes are in the form of anatase phase after annealing. Illumination of UV light on the surface of Pt/TiO2 nanotubes remarkably enhances the cyclic voltammetric and chronoamperometric responses for ammonia oxidation. This clearly demonstrates that the catalytic activity of the Pt/TiO2 nanotubes is enhanced compared to that without UV illumination due to a synergistic effect between the electrocatalysis and photocatalysis. The improved performance of the Pt/TiO2 nanotubes for ammonia oxidation is attributed to the photo-generated holes in the TiO2 which could oxidize ammonia molecules during UV illumination.