Hydrothermal synthesis of Cu2O with morphology evolution and its effect on visible-light photocatalysis

Cu2O micro-sized crystals was synthesized through a hydrothermal reaction of CuCl2 and NaOH solution adding ascorbic acid (AH(2)) as reductant. The morphology changed from truncated octahedral to six-corners-{111} truncated octahedral along with the increasing molar ratio of NaOH/CuCl2. The preferential growth rates of the {111} and {110} faces affected by the concentration of [Cu(OH)(4)](2-), resulting in the morphological evolution. The sufficient AH(2) has an etching effect to form a quasi-spherical Cu2O structure. The highly-truncated octahedral Cu2O with the dominant {110} faces has higher adsorption and also photocatalytic activity with a methyl orange (MO) degradation rate of 90.3% under visible light. It's proposed that the {110} faces of Cu2O microcrystals possess higher photocatalytic activity than {111} faces, and are even more active than the {100} faces. (C) 2021 Elsevier B.V. All rights reserved.