Growth of MoS₂ nanoflakes and the photoelectric response properties of MoS₂/TiO₂ NRs compositions

The initial reactant concentration and the substrate play an important role on the nucleation and growth of MoS₂ nanostructures during hydrothermal growth. In this work, MoS₂ nanoflakes are grown on FTO and TiO₂ nanorod arrays (NRs) substrates. The morphology, optical and photoelectric properties of MoS₂ nanoflakes are affected by the initial reactant concentration. Compared with the FTO substrate, MoS₂ nanoflakes tend to grow on TiO₂ NRs substrates due to less mismatch between TiO₂ and MoS₂. The large surface roughness and the presence of surface states of the TiO₂ NRs facilitate the nucleation and growth of MoS₂ nanoflakes. The photoelectric characteristics of MoS₂/TiO₂ NRs compositions have been investigated. The MoS₂/TiO₂ NRs compositions prepared using the initial reactant concentration with 4 mM S atom concentration exhibit the higher photoresponse behavior, which is attributed to the better heterojunction contact interface between MoS₂ nanoflakes and TiO₂ NRs. MoS₂ nanoflakes can not completely cover the TiO₂ NRs under low initial reactant concentration, resulting in the small area of the contact interface. On the other hand, MoS₂ nanoflakes tend to form the self-assembly nanoflowers under high initial reactant concentration, which induces the carriers recombination in MoS₂, the poor transport properties of MoS₂ and the detrimental effects on the photogenerated current.