Recently, aluminum titanate (Al2TiO5)-based nanostructures have been proved to serve as an efficient photocatalytic material with satisfactory photodegradation capacity. In this study, the citrate sol-gel method was used to synthesize these nanostructures and inspect the significant impacts of nitrogen-doping-originated crystalline defects on their photocatalytic performance in some details for the first time. The results indicated that the penetration of nitrogen atoms into AT crystal lattice, depending on the nitriding time and temperature, can induce a great deal of the residual stress and result in propagating the existing cracks and breaking down the particles. The XPS and FTIR results confirmed the formation of some new bonds in the crystal structure (including O-Ti-N and Ti-N), the substitutional and interstitial replacement of nitrogen atoms with oxygen atoms, oxygen vacancies, and the attachment of nitrogen species at superficial oxygen sites. These events may vary the bandgap values from 2.88 eV for pristine AT to 2.73 eV for the nitrided one, thereby manipulating the charge carrier recombination rate and activation of superficial catalytic reactions in the particles. Numerically, the band structure variations can efficiently increase the photodegradation efficiency of methylene blue (MB) and apparent rate constant (k) by 1.4 times (from 38.9 to 55.9%) and 1.8 times (from 0.0038 to 0.0068 min(-1)), respectively. Finally, the results show that the synthesized photocatalyst can successfully compete with TiO2-based photocatalysts in terms of photocatalytic performance. (C) 2020 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.