Self-assembly graphitic carbon nitride quantum dots anchored on TiO₂ nanotube arrays: An efficient heterojunction for pollutants degradation under solar light

In this study, an efficient heterojunction was constructed by anchoring graphitic carbon nitride quantum dots onto TiO₂ nanotube arrays through hydrothermal reaction strategy. The prepared graphitic carbon nitride quantum dots, which were prepared by solid-thermal reaction and sequential dialysis process, act as a sensitizer to enhance light absorption. Furthermore, it was demonstrated that the charge transfer and separation in the formed heterojunction were significantly improved compared with pristine TiO₂. The prepared heterojunction was used as a photoanode, exhibiting much improved photoelectrochemical capability and excellent photo-stability under solar light illumination. The photoelectrocatalytic activities of prepared heterojunction were demonstrated by degradation of RhB and phenol in aqueous solution. The kinetic constants of RhB and phenol degradation using prepared photoelectrode are 2.4 times and 4.9 times higher than those of pristine TiO₂, respectively. Moreover, hydroxyl radicals are demonstrated to be dominant active radicals during the pollutants degradation.