Phase-transfer assisted synthesis of BiOI nanoplatelets, quantum-confined color and selective modification of surface conditioning

Nanoscale BiOI is prepared via a phase-transfer assisted reaction. To this concern, reaction of Bi(NO3)3·5H2O and KI in water/2-propanol leads to the nucleation of BiOI. These nanoparticles are separated by an oleylamine-induced phase transfer to toluene. Colloidal stabilization of BiOI in the non-polar phase can be reversed by hydrazine-initiated removal of oleylamine. With glycine as a colloidal stabilizer the particles are redispersable in a polar phase such as water or alcohol. As-prepared BiOI is platelet-shaped with sizes of 200·200·18 nm and a specific surface of 16.0 m2g−1. Due to one-dimensional size confinement, the color of the BiOI nanoplatelets – in contrast to carmine red bulk-BiOI (Eg: 1.83 eV) – is shifted to yellow (Eg: 2.00 eV). Based on its adaptable dispersibility and its color, BiOI nanoplatelets might be relevant as a color pigment as well as a semiconductor in solar cells.

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