Boric acid modified polydopamine and nanocolumnar hydrogenated TiO2 nanocomposite with improved photocatalytic performance

Abstract

Hydrogenation has been established as one of the most common approaches to increase the photocatalytic efficiency of TiO₂ nanomaterials. Nanocolumnar hydrogenated TiO₂ (H:TiO₂), obtained through a combination of DC reactive magnetron sputtering and hydrogenation treatments, could serve as an efficient photocatalyst, provided that its chemical stability and the lifetime of its photogenerated charge carriers are improved. One possible strategy to achieve this is the large-scale deposition of the nanometrically thin free-standing polydopamine film from the air/water interface. This exciting approach is feasible due to the superior mechanical stability of the boric acid-modified polydopamine (BAPDA) thin films. The gradual preparation protocol successfully produced the BAPDA/H:TiO₂ nanocomposites, as revealed by X-ray diffractometry, Raman spectroscopy, atomic force microscopy and X-ray photoelectron spectroscopy. Next, comparing bare H:TiO₂ and BAPDA/H:TiO₂, 0.15 eV bandgap redshift was observed through UV–vis spectroscopy. Additionally, photoelectrochemical tests provided auspicious results for photocatalytic oxidation by an increase in photocurrent density in the anodic regime and more negative polarization of the BAPDA/H:TiO₂ photoelectrode. Analysis of the open circuit photopotential decay curve indicated a rise in photogenerated electron lifetime. Finally, photocatalytic Methylene Blue degradation tests demonstrated a higher photocatalytic efficiency for the nanocomposite resulting from the boric acid-modified polydopamine deposition.