Study on titania nanotube arrays prepared by titanium anodization in NH4F/H2SO4 solution

In this paper, the formation of titania nanotube arrays was investigated in NH4F/H2SO4 electrolyte. Under optimized electrolyte conditions, the titania nanotube arrays with an inner diameter of about 120 nm and a length of about 300 nm was obtained. During the formation process, the variety of current was observed. The current–time curve implied that the evolvement process of titania nanotube arrays include three stages. The stability of titania nanotube arrays at elevated temperatures was studied. The as-prepared titania nanotube arrays is amorphous, crystallized in anatase and rutile as the rising of the temperature. The samples were characterized by ESEM and XRD.