RESUMO
Platinum nanocrystals with a fine control of the crystal domain size in the range 1.0-2.2 nm are produced by tuning the NaOH concentration during the UV-induced reduction of H2PtCl6 in surfactant-free alkaline ethylene glycol. The colloidal solutions obtained are characterized by transmission electron microscopy and pair distribution function analysis, allowing analysis of both atomic and nanoscale structures. The obtained nanoparticles exhibit a face-centered cubic crystal structure even for the smallest nanoparticles, and the cubic unit cell parameter is significantly reduced with decreasing crystallite size. It is further demonstrated how the "UV-approach" can be used to achieve spatial control of the nucleation and growth of the platinum nanocrystals, which is not possible by thermal reduction.