Simultaneous tuning of particle size and phase composition of TiO_2-δ nanoparticles by a simple liquid immiscibility strategy

Oxygen deficient TiO_2-δ nanoparticle has raised wide research interests as electrocatalysts, however, it is challenging to tune the particle size and phase composition simultaneously to optimize its performance. Here we prepared TiO_2-δ nanoparticles taking advantage of the liquid immiscibility phenomenon in TiO₂-SiO₂ system by aerodynamic levitation (ALD), and employed a simple parameter, the resident time in the immiscibility region, to achieve simultaneous tuning of particle size and phase composition. A quantitative relationship between the particle size and the mass fraction of rutile phase was established, and the formation mechanism of the two-phase particle was proposed. Furthermore, the synthesized TiO_2-δ nanoparticles were evaluated as electrocatalysts for reducing nitrate to ammonia, which showed better performance than the commercial TiO₂ nanopowder. Results from this work provide a simultaneous tuning strategy for regulating the particle size and phase compositions of TiO_2-δ nanoparticles by controllable solidification, and broaden the potential application of TiO_2-δ.