Synthesis of large 2D oxide nanosheets by virtual substrate method and growth-kinetics studies using prototype CuO/MgO

Abstract

We present a novel virtual substrate method for large metal oxide nanosheets synthesis. Ashless filter paper was used as the novel virtual substrate and combustive oxidation was used as the synthesis route. CuO/MgO with different proportion in the final produce were selected as model prototype materials to study synthesis kinetics. Aqueous soluble acetate precursors were utilized, and the products were characterized by powder x-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM). The selection of these prototypes was based on their contrasting crystallographic properties and contrasting physico-chemical properties of the respective acetate precursors. This method yields polycrystalline (grain size tens of nm) nanosheets with a thickness of ∼3 nm, which percolate to form centimeter-long freestanding structures. Our synthesis kinetics model establishes that in case of mixed precursor, the precursor with higher solubility/aqueous affinity gets precedence in attaining sheet morphology. In the case of a single precursor, nanosheets were always formed. The growth kinetics for the metal oxide nanosheets is discussed.