Modulation of stoichiometry, morphology and composition of transition metal oxide nanostructures through hot wire chemical vapor deposition

A hot wire chemical vapor deposition technique is described for synthesis of 1D nanostructures of a controlled morphology, stoichiometry, and composition. The synthesis involves the evaporation and condensation of metal oxide vapor through the reaction of oxygen with the hot filaments of respective transition metals. The stoichiometry and morphology of MoO3 and WO3 were modulated by varying the filament temperature and partial pressure of oxygen in the growth chamber. Based on the results under different conditions, a morphological phase diagram, and a growth model based on the extent of gas phase supersaturation were developed to understand the growth mechanism. Further, ternary transition metal oxide, NiMoO4, was synthesized as a proof-of-concept for tuning the composition of deposition through simultaneous evaporation of two metal oxides.