Abstract: Photocatalytic mineralization of recalcitrant contaminants such as phenol requires hydroxyl radicals (·OH) for ring-opening reactions. Here, we weaken the adsorption of oxygen species on TiO₂ surface by Al doping, which can effectively promote the photoinduced ·OH generation. Besides, Al doping can downshift the conduction band of TiO₂. The resulted potential barrier lowering can promote semiconductor-cocatalyst interfacial electron transfer for the reduction half-reaction. Due to the strong correlation between positive and negative charges, the rapid transfer of electrons in the reduction half-reaction can also increase the concentration of holes in the semiconductor and promote the generation of ·OH. By immobilizing the photocatalyst on the light-incident inner wall of the reactor, it can avoid the competitive light absorption by the contaminant. By these virtues, efficient photocatalytic mineralization of low-concentration phenol in wastewater can be realized.