Photocatalytic and eletrocatalytic activity of black TiO ₂ nanotube arrays by aluminothermic reduction

Abstract

The black TiO2 nanotubes arrays were prepared by anodizing and aluminothermic reduction process. The prepared samples were characterized by X‐ray diffraction (XRD), SEM, UV‐visible absorption spectroscopy and X‐ray photoelectron spectroscopy (XPS). The photochemical/electrical catalytic activity of the samples before and after blackening treatment was tested. Comparing with the raw TiO2, the macrostructure of the black TiO2 nanotube arrays changes a little, and the tubal walls become a little thicker and rough. The photocatalytic hydrogen production rate has an obvious enhancement (from 8.9 µmol cm−2 h−1 to 22.8 µmol cm−2 h−1) after the blackening treatment and the electrocatalytic H2 evolution rate is also improved with a lower onset potential. The increment of trivalent Ti3+ on the surface is confirmed by XPS and presented by the colour changing of the samples (from white colour to black). The hybrid energy band gap and reduced charge transfer barrier are proved to be essential in promoting the catalytic properties of the black TiO2 nanotube arrays.

Tackling Challenges of Long-Term Electrode Stability in Electrochemical Treatment of 1,4-Dioxane in Groundwater

“…XRD diffractogram did not change through the anodization (Figure S4), suggesting an amorphous TiO 2 structure consistent with previous reports. 52 We then applied a two-step reduction process to partially convert Ti(IV) in TiO 2 into conductive, electrocatalytically active Ti(III) (Figure 1a). The reduced TiO x NT (1 < x < 2) mesh turned bluish black, but there was no significant change regarding the length, diameter, or morphology of the nanotubes (Figures 1c and S3).…”

“…A closer look via SEM suggests that the surface of the mesh became uniformly coated with a dense layer of vertically aligned nanotubes with an average length of ∼6 μm and a diameter of ∼60 nm (Figures b and S3). XRD diffractogram did not change through the anodization (Figure S4), suggesting an amorphous TiO 2 structure consistent with previous reports . We then applied a two-step reduction process to partially convert Ti­(IV) in TiO 2 into conductive, electrocatalytically active Ti­(III) (Figure a).…”