Zhang Jin, Wang Hong, Xiao Yiming, Tang Ju, Liang Changneng, Li Fengyan, Dong Haiming, Xu Wen
School of Physics and Astronomy and International Joint Research Center for Optoelectronic and Energy Materials, Yunnan University, Kunming, 650091, People's Republic of China.
Department of Physics, China University of Mining and Technology, Xuzhou, 221116, People's Republic of China.
Nanoscale Res Lett. 2017 Nov 29;12(1):611. doi: 10.1186/s11671-017-2369-1.
We present an investigation on carbon quantum dots (CQDs) synthesized from wastewater induced during the production of tofu. We find that tofu wastewater is a good source of raw material in making fluorescent CQDs. The corresponding CQDs can be fabricated simply via hydrothermal reaction to carbonize the organic matter in the yellow serofluid of tofu wastewater. Two sorts of CQDs can be obtained within the deionized water and NaOH solution, respectively, where the CQDs in water (NaOH solution) can emit blue (green) light under the UV irradiation. It is found from X-ray photoelectron spectroscopy (XPS) that the basic difference between these two sorts of CQDs is the contents of C-O and C=O bonds on the surface of the CQDs. This difference can cause different features of the photoluminescence (PL) spectra of the CQDs. On the basis of the obtained results from the XPS and PL measurements, we propose a mechanism in understanding and explaining the photon-induced light emission from CQDs. This study is relevant to the fabrication and application of fluorescent CQDs as, e.g., light display materials.
我们展示了一项关于由豆腐生产过程中产生的废水合成碳量子点（CQDs）的研究。我们发现豆腐废水是制备荧光碳量子点的良好原料来源。相应的碳量子点可以通过水热反应简单地制备，将豆腐废水黄色浆液中的有机物碳化。分别在去离子水和氢氧化钠溶液中可以得到两种碳量子点，其中水中（氢氧化钠溶液中）的碳量子点在紫外光照射下能发出蓝色（绿色）光。通过X射线光电子能谱（XPS）发现，这两种碳量子点的基本差异在于碳量子点表面C-O键和C=O键的含量。这种差异会导致碳量子点光致发光（PL）光谱的不同特征。基于XPS和PL测量获得的结果，我们提出了一种理解和解释碳量子点光子诱导发光的机制。这项研究与荧光碳量子点的制备和应用相关，例如作为光显示材料。
