Surface treated TiO2 nanorod arrays for the improvement of water splitting

•The original TiO2 nanorods were synthesized without TiO2 seed layer.•TiCl4 are applied on the TiO2 nanorod arrays to synthesis TiO2–TiCl4 samples.•Titanium butoxide solution are applied in synthesized TiO2–H2O samples.•The surface areas of the TiO2–TiCl4 and TiO2–H2O are obviously increased.•The IPCE of the treated samples are greatly enhanced.

Water splitting is widely employed for the hydrogen production for its abundant sources of water and sunlight. The TiO2 nanostructures are the most promising materials because of their properties of the non-toxicity and relatively low cost. Surface treatments with TiCl4 solution and titanium butoxide solution are applied on the TiO2 nanorod arrays respectively. On the surface of the TiO2 nanorods, TiO2 nanoparticles are prepared through hydrolysis of TiCl4 and homogeneous phase of TiO2 synthesized with assist of second hydrothermal synthesis in titanium butoxide, resulting in the increase of the surface area of the TiO2. Comparing with that of the original TiO2 nanorod arrays, the incident photon-to-electron conversion efficiency (IPCE) of the TiO2–TiCl4 and TiO2–H2O samples is greatly enhanced by 25% and 250% in the ultraviolet region, respectively. The obviously enhanced activity is due to the larger surface structure after treatments, which could contribute to the improved performance in the water splitting. These surface treatments provide an efficient way to regulate the properties of the TiO2 nanorod arrays for their extensive applications in the solar device for the hydrogen production.