Designed and controlled synthesis of visible light active copper(I) oxide photocatalyst: From cubes towards the polyhedrons - with Cu nanoparticles

In the present work Cu2O shape tailored microcrystals were obtained and investigated. The used shape-tailoring approach was based upon the variation of the starting precursor (copper(II) acetate and copper(II) chloride, the latter one being also much more cheaper and easily accessible), the synthesis temperature (60, 70 and 80 degrees C, respectively) and the shape tailoring agent applied (PVP vs. EDTA). It was found that cubic and polyhedral monodisperse microcrystals were obtained, which showed enhance visible light photocatalytic activity in the degradation of methyl orange. The activity was dependent of the formation of metallic Cu (the formed metallic nanoparticles were obtained when PVP was used), the microcrystals' size and morphology. The band-gap values were directly linkable to the obtained photocatalytic activity, while in the first derivative DRS spectra the electron transition contribution of facet (111) was also found, alongside of the polycrystalline Cu2O electron transition contribution. Also, the surface hydrophylicity played a crucial role in the determination of the photocatalytic properties as evidenced by IR measurements and DLS investigations as well.