Nucleation and growth of mixed vanadium-titanium oxo-alkoxy nanoparticles in sol-gel synthesis

[Display omitted] •Nucleation-growth process of vanadium-titanium oxo-alkoxy species was investigated.•At V ≤ 20 mol%, Ti species nucleate serving attraction centres for V species.•At V > 20 mol%, hydrolysed V species imprison small Ti species prohibiting nucleation.•Nucleus size significantly increases with an increase of precursor concentration. The mixed vanadium-titanium oxo-alkoxy (VTOA) nanoparticles were synthesized via sol-gel method in a chemical reactor with ultra-rapid micromixing. The nucleation and growth kinetics and particles size, followed by the static/dynamic light scattering methods, were quite different from those of pure oxo-alkoxy titanium (TOA) and vanadium (VOA) species. It was shown that the TOA species appear first and serve to be centres of attraction for hydrolysed VOA species at the nucleation stage. However, at the vanadium content above 20 mol% large VOA species imprison sub-nucleus TOA species prohibiting the nucleus appearance. The model analysis of the VTOA induction kinetics validated a significant increase of the nucleus size with an increase of the precursor concentration. The results support a new paradigm of the sol-gel process describing profound restructuring of the oxometallic species during assembling at the nucleation stage.