Highly stable functionalized cuprous oxide nanoparticles for photocatalytic degradation of methylene blue.

We report the synthesis and characterization of Cu 2 O nanoparticles (NPs) in the presence of the coordinating ligands like l -glutamic acid (Glu-Cu 2 O) and d -glucosamine (GlcN-Cu 2 O). Even if –NH 2 group is common to both the ligands, l -glutamic acid is a straight chain compound containing additional two –COOH groups, whereas, glucosamine is a cyclic compound with additional four –OH groups and an ether (-O-) linkage. Thus the coordinating ligands are different in the nature of the functional groups as well as their molecular skeletons leading to cubic morphology (∼350 nm of average edge length) for l -glutamic acid coordinated Cu 2 O and spherical morphology (∼250 nm of average diameter) for glucosamine one as observed by Field Effective Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM) images. The observed band gap of Cu 2 O of 1.89 eV is decreased to 1.84 ev for both the ligated structures. Both the ligated cuprous oxide (Cu 2 O) nanoparticles (NPs) were used for the photocatalytic degradation of methylene Blue (MB). The spherical GlcN-Cu 2 O showed 98% degradation of MB in 105 min and after 3 cycles of operation, the photocatalytic activity was enough for the 93% degradation of the dye, whereas, the cubic Gu-Cu 2 O could degrade MB up to 97% in 135 min and after three cycles, only 86% of the dye was degraded. This indicates, the molecular skeleton and functional groups on the ligand control the shape and size of the Cu 2 O nanoparticles as well as the photocatalytic efficiency and stability. It is presumed, the cyclic glucosamine ligand can protect the Cu 2 O nanoparticles from erosion during the degradation process. [ABSTRACT FROM AUTHOR]