Shape Effects of Cu2O Polyhedral Microcrystals on Photocatalytic Activity

Perfect mixed 26-facet and 18-facet polyhedra of Cu2O microcrystals were successfully synthesized by a hydrothermal process with use of stearic acid as a structure-directing agent. Cu2O octahedra and cubes were also prepared under hydrothermal conditions. The obtained microstructures were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and UV−vis spectrum. The adsorption and photocatalytic activity of as-prepared 26-facet and 18-facet Cu2O polyhedra for decomposition of methyl orange were investigated and compared to that of octahedra and cubes. The results show that mixed 26-facet and 18-facet polyhedra with dominant {110} facets have a higher adsorption and photocatalytic activity than Cu2O octahedra with dominant {111} surfaces and cubes with {100} surfaces. A higher surface energy and a greater density of the “Cu” dangling bonds on {110} facets of 26-facet and 18-facet polyhedra may be ascribed to its higher catalytic activity. Moreover, as compared with octahedra and cubes, mixed 26-facet and 18-facet polyhedra have more edges and corners, which could improve photocatalytic activity. This simple one-pot synthetic route could provide a good starting point for the research of morphology construction and shape-dependent catalytic properties of other materials.