Chemical Regulation of Carbon Quantum Dots from Synthesis to Photocatalytic Activity
Chemical Regulation of Carbon Quantum Dots from Synthesis to Photocatalytic Activity
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碳量子点从合成到光催化活性的化学调控
DOI：
10.1002/asia.201300076
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发表时间：
2013-05-01
影响因子：
4.1
通讯作者：
Cao, Shirui
中科院分区：
文献类型：
--
作者：
Hu, Shengliang;Tian, Ruixue;Cao, Shirui
通过在 HNO3 溶液中回流加热各种碳源来合成碳量子点（CQD），并研究了 HNO3 浓度对 CQD 尺寸的影响。此外，所制备的 CQD 的含氧表面基团被 NaBH4 选择性还原，从而产生新的表面态。实验结果表明，HNO3浓度可以调节CQD的尺寸，进而影响其光致发光行为；光致发光性能与CQD的尺寸和表面状态有关，但光催化活性仅由表面状态决定。 CQD表面不同的含氧基团可以引起不同程度的能带向上弯曲，从而决定电子空穴对的分离和结合。由CO和COOH基团引起的高能带弯曲有利于电子空穴对的分离，从而增强高光催化活性。相反，COH基团引起的低向上能带弯曲很难阻止电子空穴对的表面复合，从而表现出强光致发光。因此，CQD 的光催化活性和光学性质都可以通过其表面状态来调节。
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.