Preparation and characterization of novel hydroxyapatite/copper assemblies with well-defined morphologies

Micrometer-sized powders with small crystallite sizes, high dispersion, and high copper contents, like Cu and/or Cu₂O assembled on core particles would find potential applications in fields of catalysts, transparent conducting films and plasmonic-based technologies. Novel hydroxyapatite (HA)/copper assemblies were synthesized via a facile glucose reduction route. During hydrothermal treatment, copper ions were firstly released after dissolution of copper-modified HA, then reduced by glucose and finally assembled as shell on HA aggregates. After 12 h, cuprous oxide grew with truncated-octahedron morphology. When the reduction time was prolonged to 24 and 36 h, Cu phase was formed in situ via glucose reduction of Cu₂O. Interestingly, HA/copper assemblies with well-defined morphologies were prepared under different reaction conditions. With presence of more Na₂CO₃, the reduction of copper ion occurred at a fast rate, which resulted in formation of spherical assemblies. Contrastingly, reduction reaction hardly occurred without Na₂CO₃ addition and assemblies with irregular morphology were prepared. Additionally, copper fibers with length of millimeters were prepared without Na₃Cit addition. The UV–Vis absorbance peak of assemblies showed a blue or red shift due to the effect of crystalline size and/or hollowing process.