Visible light photoelectrocatalysis with salicylic acid-modified TiO2 nanotube array electrode for p-nitrophenol degradation.

This research focused on immersion method synthesis of visible light active salicylic acid (SA)-modified TiO2 nanotube array electrode and its photoelectrocatalytic (PEC) activity. The SA-modified TiO2 nanotube array electrode was synthesized by immersing in SA solution with an anodized TiO2 nanotube array electrode. Scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), UV-vis diffuse reflectance spectrum (DRS), and Surface photovoltage (SPV) were used to characterize this electrode. It was found that SA-modified TiO2 nanotube array electrode absorbed well into visible region and exhibited enhanced visible light PEC activity on the degradation of p-nitrophenol (PNP). The degradation efficiencies increased from 63 to 100% under UV light, and 79-100% under visible light (lambda>400 nm), compared with TiO2 nanotube array electrode. The enhanced PEC activity of SA-modified TiO2 nanotube array electrode was attributed to the amount of surface hydroxyl groups introduced by SA-modification and the extension of absorption wavelength range.