LAUSR

ABSTRACT Microwave irradiation (2.45 GHz) was used to synthesize nano-structured ZnO. The main precursors used were Zn(NO3)2.6H2O and NaOH with molar ratio of Zn2+:OH− = 1:15. The powers for microwave heating were selected at 320 and 480 watts with 10 min synthesis time and 5s/15s on/off step. The charged particles vibrating in the electric field formed nuclei and grew in the temperature gradient in the solution leading to crystal growth in different directions. This study investigated the formation of nanostructured ZnO by microwave heating method using polyethylene glycols (MW = 1500 and MW = 4000), sugar and cassava starch as structure-directing agents. All the synthesized microwave conditions gave single phase of ZnO with wurtzite structure. The size of ZnO nanocrystals increased with increasing microwave power and the optical band gap energy values varied between 3.10 and 3.24 eV. Photocatalytic behavior of ZnO was studied through photodegradation of methylene blue. The highest photodegradation rate in this investigation was from PEG1500 modified nanostructured ZnO where they developed into fine rod-like particles.