Fabrication of an in situ-grown TiO2 nanowire thin film and its enhanced photocatalytic activity

TiO 2 is a promising photocatalyst used in practical environmental remediation. TiO 2 photocatalysts are usually implemented in two forms: suspended powder and immobilized thin films. A simple technique for fabricating TiO 2 thin film photocatalyst was developed in this work. The fabricated TiO 2 thin film photocatalyst featured a homogeneous nanowire layer grown in situ on the parent Ti plate. The optimized fabrication protocol was to soak the ultrasonically cleaned and acid-washed Ti plate in 30% H 2 O 2 solution containing 3.2 mM melamine and 0.29 M HNO 3 at 80 °C for 72 h and then anneal at 450 °C for 1 h. TiO 2 nanowires with uniform diameters were homogeneously arrayed on the Ti plate surface. The thickness of the TiO 2 nanowire array layer was 1.5 μm. The pore properties of the TiO 2 thin film were close to those of P25. The band gap of the fabricated photocatalyst was 3.14 eV. The photocatalytic activity of the fabricated photocatalyst toward 10 mg/L RhB and 1 mg/L CBZ demonstrated greater than 60% degradation under 2 h UVC irradiation. The RhB and CBZ degradation efficiencies remained at a good level after 5 consecutive cycles. Mechanical wearing, such as 2 min sonication, will not lead to significant suppression of the photocatalytic activity. Photocatalytic RhB and CBZ degradation using the fabricated photocatalyst favored an acidic > alkaline > neutral environment. The presence of Cl − slightly suppressed the photocatalytic degradation kinetics. However, RhB and CBZ photocatalytic degradation kinetics were promoted in the copresence of SO 4 2− or NO 3 − .