Simultaneous copper ion removal and hydrogen production from water over a TiO₂ nanotube photocatalyst

A one-dimensional (1-D) mesoporous TiO₂ nanotube (TiNT) was successfully synthesized via a hydrothermal-calcination process, and employed in simultaneous photocatalytic Cu²⁺ removal and H₂ production. Under irradiation, Cu²⁺ in the wide concentration range of 8–800 ppm, could be reduced rapidly, and the reduction was not severely impacted by co-existing inorganic ions in solution. Simultaneous with Cu²⁺ reduction, noticeable H₂ was produced over the in-situ fabricated Cu incorporated TiNT (Cu–TiNT) photocatalyst, while H₂ evolution rate was controlled by the Cu²⁺ reduction process, due to competition of electron capture between protons and Cu²⁺. In addition, H₂ generation activity of Cu–TiNT depended on the initial Cu²⁺/Ti ratio, and could be depressed by co-existing ions in solution. Fast Cu²⁺ reduction and remarkable H₂ evolution confirmed the feasibility of simultaneous Cu²⁺ removal and H₂ production over a TiNT photocatalyst.