Novel Candy-like Cu₄O₃ Microstructure: Facile Wet Chemical Synthesis, Formation Mechanism, and Good Long-Term Antibacterial Activities

The novel candy-like Cu4O3 microstructure has been synthesized successfully for the first time by a facile wet chemical method, and the formation mechanism was studied based on series of control experiments. The antibacterial activities of the candy-like Cu4O3 were evaluated by means of Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus saureus (S. aureus). The antibacterial mechanism was investigated by tracing the morphology evolution of the bacteria. The results show that the candy-like Cu4O3 microstructure was formed underwent the route of Cu(NH3)42+ → Cu(OH)42– → Cu(OH)2 → CuO → Cu4O3 nuclei → Cu4O3 crystal growth → candy-like Cu4O3, and optimal reaction conditions are required to obtain the candy-like Cu4O3. The candy-like Cu4O3 microstructure exhibits good long-term antibacterial activities to both E. coli and S. aureus bacteria. Critical concentration of Cu2+ ions released from the candy-like Cu4O3 was found responsible for the sudden increase beyond 90% in antibacterial activity.