Effects of additive NH3 with citric acid in the precursor and controlling the deposited thickness for growing molybdenum oxide crystals and nanorods

Abstract

In recent years, researchers have successfully established a simple method for the production of fine single crystal-like α-MoO₃ nanorod structures on substrates using a solution metal–organic decomposition (MOD) method to deposit film coatings. However, to grow α-MoO₃ nanorods by the MOD method, an accurate mechanism between α-MoO₃ nanorod extension and precursor preparation (contents of precursor conditions) should be identified. Here, we demonstrated controllable α-MoO₃ nanorods and plate-like α-MoO₃ crystal growth based on as-deposited film thickness by using different citric acid (CA) and ammonia (NH₃) ratios in the precursor solutions. The α-MoO₃ nanorod growth mechanisms are discussed in detail with the precursor conditions and deposition film thickness; excellent results were achieved in controlling the film thickness by preparation of the precursor viscosities. In addition, the effects of the CA and NH₃ amounts on the α-MoO₃ nanorods and crystal growth were investigated. It was found that NH₃ plays an effective role in delaying the decomposition timing of CA, promotes the growth of α-MoO₃ nanorods, and reduces the growth and increase of plate-like α-MoO₃ crystals. The study obtained excellent results for the growth extension of α-MoO₃ nanorods and plate-like α-MoO₃ crystals, controlled by film thickness as the role of CA and NH₃. The demonstrated strictly controlled α-MoO₃ nanostructure forming process can be achieved with the solution MOD method.