Galvanostatic electrodeposition of ZnO nanosheet: effect of different applied current densities and deposition times on the nanosheet morphology

Abstract

A systematical study of electrodeposition method using galvanostatic (constant current) mode has been performed to obtain ZnO nanosheet film on ITO substrate in the standard 3-electrode electrochemical system. Zinc nitrate solution containing acetate ions as the controlling agent was used as the electrolyte. Three applied current densities were implemented: –1, –3 and –5 mA cm−2 with various deposition times, to study the effect of these deposition parameters on the nanosheet morphology. Nanosheet structures can be observed for all applied current variations after sufficient deposition times. Prolonging the deposition results in the formation of ZnO layer underneath the nanosheet (under-layer), with different morphologies: dense-like for –1 mA cm−2, and particle-like for –3 and –5 mA cm−2. The dense-like under-layer shows much better attachment with the substrate whereas no peeling off was observed even after deposition for up to 10800 mC cm−2, while the opposite was observed for the particle-like ones. A complete discussion of the crystal growth mechanism will be presented, and the origin of the under-layer formation will also be addressed.