Anodic Fabrication of Highly Ordered TiO2 Nanotube Arrays and Its Hydrogen Sensing

In this paper, highly ordered TiO2 nanotube arrays are fabricated via electrochemical anodization of high purity Ti foil in fluorine containing electrolytes. The field emission scanning electron microscopy measurements show that the morphology of TiO2 nanotube arrays is affected by the two-step anodization process and the polar solvent containing electrolytes. With two-step anodization, the surface morphology of TiO2 nanotube arrays is orderly and uniform. Moreover, the pore diameter is stupendously homogeneous. The structural parameters of TiO2 nanotube arrays were improved by the addition of polar solvent, water, to electrolytes. After annealing treatment and Pd nanoparticle doping, the hydrogen sensing characteristics of TiO2 nanotube arrays were analyzed by measuring its electric resistance response in different H-2 concentrations. The results demonstrate that TiO2 nanotube arrays have high hydrogen sensitivity at room temperature.