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[en] Graphical abstract: N-doped P25 TiO2–amorphous Al2O3 composites were facile prepared via one-step solution combustion, which showed much higher visible-light photocatalytic activity than that of P25 TiO2 due to the N-doping in the high temperature combustion process, synergetic effect between amorphous Al2O3 and TiO2, and high specific surface area. Highlights: ► N-doped P25 TiO2–amorphous Al2O3 composites were prepared via solution combustion. ► The composites showed much higher visible light activity than that of P25 TiO2. ► Amorphous Al2O3 was firstly found to be a photocatalyst under UV light illumination. ► Probable photocatalytic mechanism under visible light irradiation was proposed. - Abstract: Nitrogen-doped Degussa P25 TiO2–amorphous Al2O3 composites were prepared via facile solution combustion. The composites were characterised using X-ray diffraction, high-resolution transmission microscopy, scanning electron microscopy, nitrogen adsorption–desorption measurements, X-ray photoelectron spectroscopy, UV–vis light-diffusion reflectance spectrometry (DRS), zeta-potential measurements, and photoluminescence spectroscopy. The DRS results showed that TiO2 and amorphous Al2O3 exhibited absorption in the UV region. However, the Al2O3/TiO2 composite exhibited visible-light absorption, which was attributed to N-doping during high-temperature combustion and to alterations in the electronic structure of Ti species induced by the addition of Al. The optimal molar ratio of TiO2 to Al2O3 was 1.5:1, and this composite exhibited a large specific surface area of 152 m2/g, surface positive charges, and enhanced photocatalytic activity. These characteristics enhanced the degradation rate of anionic methylene orange, which was 43.6 times greater than that of pure P25 TiO2. The high visible-light photocatalytic activity was attributed to synthetic effects between amorphous Al2O3 and TiO2, low recombination efficiency of photo-excited electrons and holes, N-doping, and a large specific surface area. Experiments that involved radical scavengers indicated that ·OH and O2·− were the main reactive species. A potential photocatalytic mechanism was also proposed.