期刊
CHEMISTRY-AN ASIAN JOURNAL
卷 8, 期 5, 页码 1035-1041出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/asia.201300076
关键词
carbon; luminescene; nanostructures; photocatalysis; surface chemistry
资金
- National Natural Science Foundation of China [50902126, 51172214, 51272301]
- China Post-doctoral Science Foundation [2012M510788]
- Program for the Top Young Academic Leaders of Higher Learning Institutions of Shanxi
- Innovation Method Special Project of Ministry of Science and Technology of China [2011M030800]
- State Key Laboratory of New Ceramic and Fine Processing, Tsinghua University
Carbon quantum dots (CQDs) were synthesized by heating various carbon sources in HNO3 solution at reflux, and the effects of HNO3 concentration on the size of the CQDs were investigated. Furthermore, the oxygen-containing surface groups of as-prepared CQDs were selectively reduced by NaBH4, leading to new surface states. The experimental results show that the sizes of CQDs can be tuned by HNO3 concentration and then influence their photoluminescent behaviors; the photoluminescent properties are related to both the size and surface state of the CQDs, but the photocatalytic activities are determined by surface states alone. The different oxygen-containing groups on the surface of the CQDs can induce different degrees of the band bending upward, which determine the separation and combination of the electronhole pairs. The high upward band bending, which is induced by CO and COOH groups, facilitates separation of the electronhole pairs and then enhances high photocatalytic activity. In contrast, the low upward band bending induced by COH groups hardly prevents the electronhole pairs from surface recombination and then exhibits strong photoluminescence. Therefore, both the photocatalytic activities and optical properties of CQDs can be tuned by their surface states.
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