Shape Evolution and Size-Controllable Synthesis of Cu2O Octahedra and Their Morphology-Dependent Photocatalytic Properties

Abstract

Octahedral Cu₂O crystals with tunable edge length were synthesized by reducing copper hydroxide with hydrazine without using any surfactant. Systematic experiments were carried out to investigate the factors which impact on the morphology and size of the products. The molar ratios of the reagents (NH₃:Cu²⁺ and OH^-:Cu²⁺) determined the morphology and size of the corresponding products via affecting the coordination between NH₃ and Cu²⁺. It is demonstrated that the ratio of growth rate along 〈111〉 versus 〈100〉 was varied by adjusting the molar ratio of NH₃ to Cu²⁺, thus Cu₂O crystals with different morphologies such as spheres, cubelike, and octahedra were obtained. The edge lengths of octahedra can be easily tuned from 130 to 600 nm by adjusting the molar ratio of OH^- to Cu²⁺. It is an effective and facile method for the controlled synthesis of octahedral Cu₂O. The obtained octahedral Cu₂O particles show improved ability on adsorption and photodegradation of methyl orange compared with cubic Cu₂O particles.