Photoelectrochemical water splitting and simultaneous photoelectrocatalytic degradation of organic pollutant on highly smooth and ordered TiO₂ nanotube arrays

The photoelectrochemical water splitting and simultaneous photoelectrocatalytic degradation of organic pollutant were achieved on TiO ₂ nanotube electrodes with double purposes of environmental protection and renewable energy production under illumination of simulated solar light. The TiO₂ nanotube arrays (TiO₂ NTs) were fabricated by a two-step anodization method. The TiO₂ NTs prepared in two-step anodization process (2-step TiO₂ NTs) showed much better surface smoothness and tube orderliness than TiO₂ NTs prepared in one-step anodization process (1-step TiO₂ NTs). In the photoelectrochemical water splitting and simultaneous photoelectrocatalytic decomposition process, the 2-step TiO₂ NTs electrode showed both highest photo-conversion efficiency of 1.25% and effective photodecomposition efficiency with existing of methylene blue (MB) as sacrificial agent and as pollutant target. Those results implied that the highly ordered nanostructures provided direct pathway and uniform electric field distribution for effective charges transfer, as well as superior capabilities of light harvesting.