Synthesis of nanocrystalline eskolaite via grimaldiite

Grimaldiite (α-CrOOH) was precipitated hydrothermally from the CrCl3 aqueous solution in the presence of hexamethylenetetramine (HMTA). The crystallite size of grimaldiite samples was estimated to be ~ 2 nm. Eskolaite (α-Cr2O3) was produced by the calcination of grimaldiite at 500 and 700 °C. FE-SEM images showed amorphous-like aggregates of grimaldiite due to very fine particles (crystallites), whereas eskolaite was in the form of sphere-like nanoparticles. Synthesized grimaldiite and eskolaite were used in the investigation of rhodamine B (RhB) degradation. The significant degradation percentage of RhB obtained by grimaldiite was explained as catalytic effect (in dark) and photocatalytic contribution (with illumination).