Enhanced photocatalytic performances of n-TiO2 nanotubes by uniform creation of p–n heterojunctions with p-Bi2O3 quantum dots

Abstract

An ultrasonication-assisted successive ionic layer adsorption and reaction (SILAR) strategy was developed for uniform deposition of high density p-type Bi₂O₃ quantum dots on n-type TiO₂ nanotube arrays (Bi₂O₃@TiO₂ NTAs), which were constructed by electrochemical anodization in ethylene glycol containing the electrolyte. Compared with pristine TiO₂ NTAs, the Bi₂O₃ quantum dots sensitized TiO₂ NTAs exhibited highly efficient photocatalytic degradation of methyl orange (MO). The kinetic constant of Bi₂O₃@TiO₂ NTAs prepared by an ultrasonication-assisted SILAR process of 4 cycles was 1.95 times higher than that of the pristine TiO₂ NTA counterpart. The highly efficient photocatalytic activity is attributed to the synergistic effect between the formation of a uniform p–n heterojunction with high-density for enhancing light absorption and facilitating photogenerated electron–hole separation/transfer. The results suggest that Bi₂O₃@TiO₂ p–n heterojunction nanotube arrays are very promising for enhancing the photocatalytic activity and open up a promising strategy for designing and constructing high efficiency heterogeneous semiconductor photocatalysts.