pH-dependent aggregation of citrate-capped Au nanoparticles induced by Cu ions: The competition effect of hydroxyl groups with the carboxyl groups |
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Authors: | Lin Jiang Jian Guan Lili Zhao Jun Li Wensheng Yang |
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Affiliation: | aKey Laboratory of Surface and Interface Chemistry of Jilin Province, College of Chemistry, Jilin University, Changchun 130012, PR China |
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Abstract: | The citrate-capped Au nanoparticles were found to undergo pH-dependent aggregation induced by Cu2+ ions. At low pH value (8.9), the Au nanoparticles aggregated into fractal-like structure induced by the coordination interactions between the carboxyl groups of citrate ligands and Cu2+ ions. At high pH value (10.1), the Au nanoparticles aggregated into close-packed structure attributed to the increased concentration of hydroxyl groups. The coordination interactions between the metal ions and the ligands were suppressed as a result of the competition effect of the hydroxyl groups with the carboxyl groups. The aggregation process was identified to be dominated by the cluster–cluster mechanism at the low pH value and the particle–cluster mechanism at the high pH value. |
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Keywords: | Au nanoparticles Metal ions Coordination Citrate Aggregation |
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