Synthesizing mixed-phase TiO2 semiconductor catalysts via microwave-assisted rutile seed crystal: A new approach

The study introduces a microwave-assisted rutile seed crystal (RS) method to synthesise mixed-phase TiO2 nanoparticles, controlling the rutile TiO2 (TiO2-R) phase content (gamma R) from 33.0 % to 99.3 % by adjusting the doping level of RS to 20.0 wt% in the metatitanic acid (MA). The sample, designated as MA-20, with the highest oxygen vacancy (Ov) concentration of 38.56 %, demonstrated over 99 % microwave absorption (minimum reflection loss (RL) -56.8 dB) and a heating rate of 0.836 degrees C/s under 2000 W and 20 g. RS enhanced the dielectric property of MA, facilitating phase transition from anatase TiO2 (TiO2-A) to TiO2-R above 600 degrees C, with critical temperatures between 800 and 1000 degrees C. MA-20, with a surface area of 1.9226 m2/g and pore size distribution of 9.0851 nm, showed that higher RS doping levels promoted phase transition and grain growth, thereby enhancing the crystallinity and charge transfer efficiency. More than 50 % of MA-20 particles were under 10 nm, and 94 % were below 100 nm, confirming the synthesis of TiO2 nanomaterials. MA-20 exhibited excellent electromagnetic wave storage and conversion properties. Adjusting microwave parameters and RS levels controls gamma R, offering an efficient approach for preparing mixed phase TiO2 catalysts, essential for semiconductor photocatalysis and overcoming TiO2-A limitations.