TiO2 modified with Ag nanoparticles synthesized via ultrasonic atomization-UV reduction and the use of kinetic models to determine the acetic acid photocatalytic degradation

Abstract TiO 2 surfaces modified with noble metal nanoparticles have been found to effectively reduce the photogenerated carrier recombination rate and significantly extend the light absorption properties of TiO 2 , thereby greatly increasing its photocatalytic activity. In this paper, highly ordered, double-sided TiO 2 nanotube arrays were prepared using an anodic oxidation method in a home-made reactor using glycerol/water (volume ratio 2:1) and NH 4 F (0.25 mol/L) as the electrolyte, titanium plates (10 cm × 2 cm × 0.5 mm) as the anode and graphite as the cathode at a constant voltage of 25 V. After a 2-h reaction, anatase TiO 2 nanotubes were obtained upon calcination at 450 °C for 4 h. The Ag nanoparticles on the surfaces of the TiO 2 were prepared via ultrasonic atomization-ultraviolet light reduction. First, a silver nitrate solution was sputtered into small droplets under ultrasonication. Then, the Ag + droplets were reduced to Ag nanoparticles. The surface morphologies, structures and elemental compositions were characterized using SEM, EDS, XRD and XPS. The photocatalytic activities were determined in acetic acid solutions (40–200 mg/L), and a mathematical model for catalytic degradation was established based on a hyperbolic model. The SEM results showed that the diameters of the as-prepared Ag/TiO 2 are approximately 100 nm and that the lengths are approximately 1.8 μm. The XRD crystal structure analysis shows that the anatase phase of the TiO 2 does not change during the Ag modification, and there was a peak from Ag (2 2 0). The XPS determined that the Ag atom percentage was 1.11%. The degradation of acetic acid indicated that Ag/TiO 2 has a higher photocatalytic activity than the undoped TiO 2 .