Hierarchical porous ZnO films synthesized by sol–gel method using triethylenetetramine stabilizer

Hierarchically porous ZnO films are synthesized through a novel sol–gel method using triethylenetetramine (TETA) as a stabilizer. Highly crystalline hierarchical porous ZnO thin films with different pore sizes are synthesized in various reaction mediums by altering solvents, sol concentration, the molar ratio of TETA to zinc acetate dehydrate (ZAD), and withdrawal speed. FESEM images show the formation of a hierarchical porous film with spherical and agglomerated particles in the optimized condition of ethanol as the solvent, sol concentration of 0.2 M, the molar ratio of [TETA]:[ZAD] = 2, and withdrawal speed of 30 mm/min. Increasing the solvent chain length, increasing the sol concentration, decreasing the TETA content, or increasing the withdrawal speed increases the particle size and porosity. XRD data, UV–Vis, and PL spectroscopy indicate high crystallinity with appropriate optical properties for the optimized sample. The hierarchical porous ZnO film synthesized by this method can be utilized as a photoelectrochemical electrode in devices such as photocatalysis and photoelectrochemical water splitting.