Crystal Faces of Cu₂O and Their Stabilities in Photocatalytic Reactions

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Cu2O microcrystals with well-formed facets were synthesized by a simple hydrothermal method. The surface stabilities and photocatalytic properties of Cu2O microcrystals were systematically investigated. Cu2O {100} and {110} facets gradually disappear and transform into nanosheets during the photodegradation of methyl orange (MO) dye. With the increase of irradiation time, Cu2O microcrystals completely transform into nanosheets with {111} facets. The finally formed nanosheets exhibit stable photocatalytic activities. On the basis of both experimental analysis and theoretical calculations, a novel model of charge separation among crystal faces was proposed and the morphology transformation mechanism accompanied by MO bleaching was discussed. It is concluded that Cu2O exposing {111} facets can be used as a stable photocatalyst.