Architecture of ZnO nanosheets and nanochips via zinc oxalato-hydrazinate complex

Abstract

We report the synthesis of ZnO using a zinc oxalato-hydrazinate complex method. The zinc oxalato-hydrazinate complex was synthesized at room temperature using the precursors zinc acetate and oxalic acid. Thermogravimetric studies of zinc oxalato-hydrazinate showed complete phase formation of ZnO at 450 °C. The phase purity and formation of zinc oxalato-hydrazinate prepared in aqueous and organic solvents were confirmed by X-ray diffraction. The zinc oxalato-hydrazinate was calcined and decomposed at 450 °C to obtain phase-pure ZnO. XRD pattern of ZnO showed the existence of hexagonal wurtzite structure. Field emission scanning electron microscopy and transmission electron microscopy (TEM) demonstrate nanosheet-like morphology along with hexagonal nanoparticles. TEM images of aqueous-mediated ZnO clearly show nanosheets having dimensions 1 × 1.7 μ made up of hexagonal nanoparticles of size 10–25 nm. However, ZnO prepared in methanol showed bunch of uniform spherical particles. Further, ethylene glycol-mediated ZnO shows uniform well-aligned spherical particles with chip-like morphology. We have also performed the photocatalytic activity of ZnO samples for methylene blue degradation. The ethylene glycol-mediated ZnO showed extremely good activity (k = 6.44 × 10−2 min−1) compared to aqueous (k = 4.42 × 10−2 min−1)- and methanol (k = 2.92 × 10−2 min−1)-mediated ZnOs. The higher activity in ethylene glycol-mediated ZnO is due to lower size and good crystallinity.