Basic zinc carbonate as a precursor in the solvothermal synthesis of nano-zinc oxide

Abstract

ZnO nanoparticles were synthesized solvothermally in various diols (ethylene glycol, di(ethylene glycol), tetra(ethylene glycol), 1,2-propanediol, 1,4-butanediol), using basic zinc carbonate (2ZnCO 3 ·3Zn(OH) 2) as a precursor for the first time. Since ZnCO 3 was sparingly soluble in diols the transformation reaction proceeded at a low reaction rate. Ethylene glycol was found as the most suitable medium among five diols studied yielding the smallest ZnO particles (~55nm) and short reaction time, t r (2h). Diols with shorter chain length produced smaller ZnO particles. p-Toluene sulfonic acid (p-TSA) acted as a catalyst and reduced t r from 8h to 2h in concentration of 0.02M. Optimum reaction conditions for the synthesis in ethylene glycol were 185°C and 2h. At higher p-TSA concentrations (0.04-0.08M) the size of ZnO particles was reduced from 500-800nm to 50-100nm and crystallite size to 25-30nm. Benzene sulfonic acid (BSA) and inorganic bases (LiOH, NaOH, and KOH) also showed catalytic activities. Raman and photoluminescence spectroscopies revealed high concentration of defects on ZnO surface causing the emission of visible light and giving this type of ZnO higher potential in various (opto)-electronic application in comparison to Zn(II) acetate based ZnO.