Generation of dual patterns of metal oxide nanomaterials based on seed-mediated selective growth

A facile route for the generation of the dual patterns of metal oxide nanomaterials, for example, ZnO and CuO, has been developed by printing the oxide seeds through a combination of microcontact printing (microCP) and microfluidic (microF) techniques, followed by the simultaneous growth of the two metal oxide nanomaterials in a one-step solution reaction based on hydrothermal, seed-mediated selective growth. The obtained dual patterns of ZnO nanorods and CuO nanoneedles show a sharp boundary between them, indicating well-defined dual-pattern generation. Also, the simultaneous growth of metal oxide nanomaterials is highly material-selective for the specific seeds prepatterned on substrates, resulting in the selective growth of ZnO nanorods and CuO nanoneedles on the ZnO and CuO seeds, respectively. Moreover, the generation of high-quality dual patterns has been similarly realized on a flexible poly(ethylene terephthalate) (PET) wafer. This study demonstrates the well-controlled hydrothermal growth of different metal oxide nanomaterials in the same reaction solution on the preprinted oxide seeds on the target substrates. It opens up an avenue to develop multifunctional devices of different metal oxides with the combination of microCP and microF techniques.