Solution-based fabrication of VO₂ (M) nanoparticles via lyophilisation

Thermochromic vanadium dioxide (VO₂) is the most extensively researched smart material owing to its near room-temperature phase transition at around 68 °C. Freeze drying has been employed in the solution-based fabrication of highly pure and crystalline VO₂ nanoparticles and it was found that freeze drying can largely eliminate the agglomeration issue which is common in nanoparticle fabrication. The particle size, phase transition temperature (τ_c), crystallinity and latent heat (L_H) have been systematically studied by changing the precursor concentration and annealing temperature. The freeze-dried sample (with 7.5 mL H₂O₂ in precursor) annealed at 650 °C has a particle size of ∼53 nm and τ_c of 64.5 °C, as well as high crystallinity with L_C of 36.76 J g^-1.