Dynamical Study of ZnO Nanocrystal and Zn-HDS Layered Basic Zinc Acetate Formation from Sol−Gel Route

We have pointed out that zinc based particles obtained from ethanolic solution of a zinc acetate derivative (zinc oxy-acetate, Zn4O(Ac)6) are a mixture of nanometer sized ZnO, zinc oxy-acetate, and zinc hydroxide double salt (Zn−HDS). The knowledge of the mechanisms involved in the formation of ZnO and Zn−HDS phases, and the evolution of Zn species in reaction medium was monitored in situ during 14 h by simultaneous measurements of UV−vis absorption and extended X-ray absorption fine structures (EXAFS) spectra. This spectroscopic monitoring was initialized just after the addition of an ethanolic lithium hydroxide solution ([LiOH]/[Zn] = 0.1) to the reaction medium kept under controlled temperature (40 °C). This study points out the first direct evidence of the reaction between ZnO nanoparticles and unreacted zinc oxy-acetate to form a Zn−HDS phase. The dissolution of ZnO and the reprecipitation of Zn−HDS are induced by the gradual release of water mainly produced by ethanol esterification well evidenced by gas chromatography coupled to mass spectroscopy and FT−IR measurements.