SAXS and UV–Vis combined to Quick-XAFS monitoring of ZnO nanoparticles formation and growth
Time-resolved X-ray absorption-fine structure (Quick-XAFS) and UV–Vis absorption spectroscopies were combined for monitoring simultaneously the time evolution of Zn-based species and ZnO quantum dot (Qdot) formation and growth during the sol–gel synthesis from zinc oxy-acetate
precursor solution. The time evolution of the nanostructural features of colloidal suspension was independently monitored in situ by small angle X-ray scattering (SAXS). In both cases, the monitoring was initialized just after the addition of NaOH solution (B = [OH]/[Zn] = 0.5)
to the precursor solution at 40°C. Combined time-resolved Quick-XAFS and UV–Vis data showed that the formation of ZnO colloids from the zinc oxy-acetate consumption achieves a quasi-steady-state chemical equilibrium in less than 200 s. Afterwards, the comparison of the ZnO
Qdots size and Guinier gyration radius evidences a limited aggregation process coupled to the Qdots growth. The analysis of the experimental results demonstrates that the nanocrystal coalescence and Ostwald ripening control the kinetics of the Qdot growth.
Keywords: SAXS; UV–Visible absorption; ZnO; quantum dots formation; sol–gel; time-resolved X-ray absorption
Document Type: Research Article
Affiliations: 1: Instituto de Quimica UNESP, rua Professor Francisco Degni s/n, Araraquara 14800-900, SP Brazil 2: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin – BP 48Gif-sur-Yvette 91192, France
Publication date: 01 August 2011
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