“…Many nanometal oxide semiconductors such as CuO, ZnO, or Al 2 O 3 exhibit great electrical properties, good photosensitivity, and charge mobility, thus making them promising photocatalysts in various industrial sectors . Among them, titanium dioxide (TiO 2 ) is an outstanding material for phototreatment processes owing to its nontoxicity, high photoactivity, low cost, and chemical stability. − Nevertheless, several limitations, including its rapid electron–hole (e – –h + ) pair recombination rate and relatively large bandgap (3.2 and 3.0 eV for anatase and rutile phases, respectively) due to the ultraviolet range absorption capacity, have restricted the potential of TiO 2 in practical usages. , Currently, several advanced methods have recently been performed to overcome these drawbacks of TiO 2 , namely, combination with others to form nanocomposite, , nonmetal doping, , and surface modification. , Specifically, studies on heterojunction approaches introduce not only a notable photocatalytic enhancement of the resulting material but also solutions to the major disadvantages of each sole precursor . Therefore, coupling TiO 2 with other metallic oxides can potentially narrow the bandgap energy and control the charge transfer process, which can eventually result in better photocatalytic performance. ,, …”