Nanophotocatalysts are applied for different applications, and their usage has been enhanced remarkably since a decade. On the other hand, cross-coupling reactions of C−N bonds have found increasing popularity for coupling derivatives of organic compounds such as aniline using diverse catalysts. Nanoheterogeneous photocatalysts can offer suitable platforms for the C−N coupling of aniline derivatives. However, the design of a photocatalyst on the nanoscale with remarkable activity and selectivity, made of noble-free elements, is highly welcome. In this study, the half-filled electronic configuration and shallow trapping properties of Fe were employed to reduce the energy band gap of the system. Moreover, the large ionic radius of lanthanide leads to large surface activity. Thus, bi-and trinuclear nano-oxide nanophotocatalysts were synthesized based on the titanium, iron, and lanthanide elements (Ti x Fe y O z , Ti x Fe y La m O z ) to obtain logically designed photocatalysts with high selectivity, durability, and operation speed under visible light. In addition, designing photocatalysts in the nanoscale was the ultimate target of this study to use the highest benefit of the nanoscale, which is high surface activity. The developed nanophotocatalysts were used for coupling aniline and its 10 derivatives under visible light. The mechanism of the migration of electrons and the C−N reaction was also investigated in detail. In addition, both obtained nanophotocatalysts were applied in five different solvents and eight different conditions so the best condition for the reaction could be determined. Furthermore, the photocatalytic mechanism was studied in detail. The final nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), inductively coupled plasma mass spectrometry (ICP-MS), Brunauer−Emmett−Teller (BET) surface activity, Barrett−Joyner− Halenda (BJH) method, UV−vis spectroscopy, photoluminescence emission spectra, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), NMR spectra, mass spectra, and CHN elemental analysis. Both nanocomposites exhibited high photocatalytic activities in coupling aniline and its derivatives under visible light. However, the Ti x Fe y La m O z nanophotocatalyst showed a higher activity (90% conversion to obtain 2,4 dinitro-n-phenylaniline) than the Ti x Fe y O z nanophotocatalyst (68% conversion to obtain 2,4 dinitro-n-phenylaniline), which is mainly due to its higher surface activity because of its lanthanide content.
