Oxidation Mechanism of Ti-Doped Fe3O4 (111): A Combined DFT and AIMD Study with an Experimental Verification

Magnetite, as a magnetic material, has profound and wide applications in materials synthesis and catalysis. Meanwhile, titanium-doped magnetite has a wide range of promising applications in degradation of pollutants, and catalysts. However, the gangue elements in natural magnetite often affect its comprehensive performance. In order to investigate the effect of the Ti on the oxidation properties of magnetite in depth, the physical and chemical properties of the oxidation process of Ti-doped magnetite are studied by thermogravimetric analysis and theoretical calculation. The thermogravimetric results show that with the increase of TiO2 content, the average oxidation rate of magnetite decreases, and the comprehensive oxidation performance gradually deteriorated. The calculation results show that when Ti atoms are doped in the surface system, which is conducive to the transfer of oxygen atoms on the surface, the adsorption capacity and dissociation of the surface system are greatly enhanced, thus reducing the initial temperature of surface oxidation. However, the existence of titanium atom isomorphism stabilizes the lattice structure of magnetite, which slows down the migration and diffusion rate of ions in the bulk structure, thereby affecting the overall oxidation performance of magnetite.