Room-temperature sol–gel synthesis of organic ligand-capped ZnO nanoparticles
Powders of zinc oxide nanoparticles with individual particle sizes below 10 nm in diameter are readily produced in base-induced sol–gel processes from ethanolic solutions of zinc acetate dihydrate. These particles are covered with acetate molecules and without further stabilization, they grow when stored as a powder. Here, we present three organic ligands, which reproducibly stabilize individual particle sizes <5 nm within the agglomerated powders for extended periods of time, up to months. Citric acid and 1,5-diphenyl-1,3,5-pentanetrione result in average diameters of 3 nm, whereas dimethyl-L-tartrate stabilizes 2.1 nm. X-ray diffraction and pair distribution function analysis were used to investigate the structural properties of the particles. TEM data confirm the individual particle size and crystallinity and show that the particles are agglomerated without structural coherence. Besides the introduction of these novel ligands for ZnO nanoparticles, we investigated, in particular, the influence of each synthesis step onto the final nanoparticle size in the powder. Previous studies often reported the employed synthesis parameters, but did not motivate the reasoning for their choice based on detailed experimental observations. Herein, we regard separately the steps of (i) the synthesis of the colloids, (ii) their precipitation, and (iii) the drying of the resulting gel to understand the role of the ligands therein. ZnO particles only covered with acetate grow to 5 nm during the drying process, whereas particles with any of the additional ligands retain their colloidal size of 2–3 nm. This clearly shows the efficient binding and effect of the presented ligands.
KeywordsZnO Nanoparticle Sol–gel synthesis Organic ligand Room temperature synthesis
- Briois V, Giorgetti C, Dartyge E, Baudelet F, Tokumoto MS, Pulcinelli SH, Santilli CF (2007) In situ and simultaneous nanostructural and spectroscopic studies of ZnO nanoparticle and Zn-HDS formations from hydrolysis of ethanolic zinc acetate solutions induced by water. J Sol-Gel Sci Techn 39:3253–3258Google Scholar
- Chory C, Neder RB, Korsunskiy VI, Niederdraenk F, Kumpf C, Umbach E, Schumm M, Lentze M, Geurts J, Astakhov G, Ossau W, Müller G (2007) Influence of liquid-phase synthesis parameters on particle sizes and structural properties of nanocrystalline ZnO powders. Phys Stat Sol (c) 4(9):3260–3269CrossRefGoogle Scholar
- Neder RB, Proffen T (2009) Diffuse scattering and defect structure simulation. Oxford University Press, OxfordGoogle Scholar
- Zobel M, Neder RBN, Windmüller A, Milek T, Zahn D, Kimber SAJ, in preparationGoogle Scholar