Reductant-free synthesis of oxygen vacancies-mediated TiO2 nanocrystals with enhanced photocatalytic NO removal performance: An experimental and DFT study

Herein, we developed a reductant-free strategy to fabricate oxygen vacancies-mediated (OVs-mediated) TiO2 nanocrystals. Different from the conventional reduction process, OVs-mediated TiO2 were synthesized via a low-temperature calcination in nitrogen atmosphere assisted solvothermal process. Firstly, the pristine TiO2 was synthesized by solvothermal process using the tetra-n-butyl titanate as precursor and ethanol as solvent. Because of the organic precursor and solvent, the obtained pristine TiO2 was inevitably carbon-doped. Then, low-temperature calcination in nitrogen atmosphere instead of reducing gas atmosphere was carried out to introduce the OVs into the pristine TiO2. Experimental and theoretical results revealed that the intrinsic carbon-doping was conducive to the formation of OVs. Moreover, the obtained OVs-mediated TiO2 exhibited outstanding photocatalytic performance in comparison with the commercial P25, which was attributed to the crucial roles of OVs. This work not only provided a novel synthesis of OVs-mediated TiO2, but also contributed to understanding the crucial roles of OVs.