Laux ‐type Oxidation of In 0 Nanoparticles to In 2 O 3 Retaining Particle Size and Colloidal Stability

As a conceptual study, In 0 nanoparticles are obtained by NaBH 4 ‐driven reduction of InCl 3 · 4H 2 O and transferred from a polar/hydrophilic diethylene glycol phase to a non‐polar hydrophobic dodecane phase for purification and stabilization. Finally, the In 0 nanoparticles are oxidized via a Laux ‐like reaction with nitrobenzene to In 2 O 3 nanoparticles. The challenge of the reaction is to perform the final oxidation to In 2 O 3 under mild conditions with the colloidal stability, particle size and particle size distribution of the initial In 0 nanoparticles retained. To this concern, the mean diameter of the initial In 0 nanoparticles changed from 11(1) to 14(2) nm of the oxidized In 2 O 3 nanoparticles. Such multi‐step reaction, including reduction, nucleation, phase transfer, exchange of surface capping and oxidation are of increasing importance for nanoparticles. Especially, Laux ‐type conditions with nitrobenzene as a molecular oxidizing agent of nanoparticles have not been used till now. Particle size, size distribution and chemical composition of the In 0 and In 2 O 3 nanoparticles are analyzed by DLS, SEM, XRD, FT‐IR and HRTEM.