3-D vertical arrays of TiO₂ nanotubes on Ti meshes: Efficient photoanodes for water photoelectrolysis

This paper describes a type of photoanode for water photoelectrolysis based on 3-D configurations of TiO₂ nanotube arrays, which are grown on Ti meshes in a radially outward direction. When compared with traditional 2-D arrays, under the same light irradiance, 3-D nanotube arrays demonstrate a higher surface area, which improves the photocurrent by ∼36.4% for water photoelectrolysis. In addition, the radial nature of 3-D arrays is capable of harvesting the incident light from any direction, leading to a low dependence of photocurrent on the angle of incident light. The effect of nanotube lengths on the photocatalytic activity of 3-D arrays for water photoelectrolysis has been investigated systematically. The addition of ethylene glycol in the electrolyte to function as a hole-scavenger further improves the photocurrent of 3-D arrays by ∼40%.