Low temperature synthesis of reduced titanium oxide nanotube arrays: Crystal structure transformation and enhanced field emission

There are considerable interests in the synthesis of nanostructured reduced titanium oxides because of their attractive properties. In this study, a facile and low-temperature reduction strategy using NaBH4 to yield reduced titanium oxide nanotube arrays is proposed, which significantly lowers the requirements of instruments and costing compared to the conventional strategies. Moreover, this reduction strategy results in the homogeneous crystal structure transformation of parent tetragonal anatase TiO2 nanotube arrays (TNAs) to orthorhombic Ti2.5O3 nanotube arrays with retained morphology, which show sharply improved conductivity and decreased work function. Notably, compared to the pristine TNAs precursor, the obtained Ti2.5O3 nanotube arrays show greatly enhanced field emission (FE) properties including substantially decreased turn-on field from 15.76 V/μm to 1.51 V/μm, a high current density of 5.00 mA/cm2 at an applied field of 4.03 V/μm, and an excellent FE stability.