Hydrothermal synthesis of flower-like SnO2 particles consisting of single-crystalline nanorods through crystal growth in the presence of poly(acrylic acid)

We prepared crystalline SnO2 particles from aqueous solutions of SnCl4 containing poly(acrylic acid) (PAA) by hydrothermal treatment at 150 °C. The morphology of the SnO2 particles depended on the concentration of PAA and the pH value of the precursor solutions. The flower-like SnO2 particles of ca. 100 nm in diameter consisting of needle-like units ca. 50 nm in size were obtained from the solution of [SnCl4·5H2O] = 0.1 M and [PAA] = 0.02 M containing the acidic solvents of pH 0.35 via the hydrothermal treatment. The needle-like units were found to consist of nanorods of ca. 50 nm in length and ca. 5 nm in width. The flower-like SnO2 particles were thought to be formed through the moderate nucleation and growth rates that were provided by the relatively high solubility of the Sn4+ species under the acidic conditions and the their coordination by PAA.