Low-Temperature Solvothermal Synthesis of ZnO Quantum Dots

ZnO quantum dots were synthesized via a low‐temperature solvothermal process without using surfactants. Heat treatment of ZnCl2 and NaOH solutions in tetra‐ethylene glycol at 140°C led to the formation of spherical ZnO nanoparticles consisting of the aggregates of uniform‐sized quantum dots. The particle size and morphology were characterized using transmission electron microscopy, dynamic light scattering, X‐ray diffraction, and Brunauer–Emmett–Teller gas absorption measurements. It was found that the quantum dots in the particles were single crystals of ZnO of ∼5 nm in diameter having the wurtzite structure. The quantum dots showed quantum size effects even in the agglomerated form. The growth mechanism of this new type of ZnO nanoparticles is proposed.