Semiconductor photocatalysis is a promising physicochemical process for the photodegradation of organic contaminants and bacterial detoxification. Among various oxide semiconductor photocatalysts, TiO2 has garnered considerable attention because of its outstanding properties including strong oxidizing activity, chemical and mechanical stability, corrosion resistance, and nontoxicity. This Review briefly introduces the key mechanisms of photocatalysis, highlights the recent developments pertaining to pure TiO 2 nanotube arrays and TiO2 nanotube arrays modified by non-metals, metals and semiconductors, and their applications in the photocatalytic degradation of organic dyes. The improved photocatalytic efficiencies of modified TiO2 nanotube arrays are compared with unmodified counterparts. Current challenges and prospective areas of interest in this rich field are also presented.