The evolution of structure, chemical state and photocatalytic performance of α-Fe/FeTiO3/TiO2 with the nitridation at different temperatures

α-Fe/FeTiO 3 /TiO 2 was synthesized through the reduction of Fe 3 O 4 @TiO 2 at 800   °C, and subsequently nitrided in NH 3 atmosphere at the nitridation temperature T N   =   400, 600, 800 and 1000   °C. In the crystal lattice of TiO 2 , with increasing T N , the N element itself exhibits the chemical states of TiO 2-x N x , TiN and interstitial N, and simultaneously it induces the complex variation of the chemical state of the Ti and O elements. The photocatalytic performance of the nitrided samples is not determined only by the chemical states of the N element but by the synergistic effects of chemical states of the N, Ti and O elements.