The cost-effective, high-performance fabrication of multicolor carbon quantum dots (CQDs) from biomass is critical to its prospective application. Lignin, with its phenylpropane structural unit and abundant functional groups, is a reliable precursor for the formation of high-quality CQDs. Here, CQDs from renewable lignin were successfully prepared via a two-step method, and controllable preparation of CQDs to emit blue, green, yellow, and red fluorescence was achieved by adjusting the N-containing acid dopant. The investigated fluorescence mechanism revealed that the energy bandgap of the lignin-derived CQDs decreased and the emission wavelength redshifted as the graphitization degree and number of C=O surface groups increased. The light absorption region of the BiOI photocatalysts modified with blue CQDs to red CQDs gradually broadened in the redshifted direction. In particular, compared with pure BiOI (70.9%), the red CQDs-modified BiOI (RCQD/BOI) can remove 94.7% of antibiotics within 60 min of light irradiation. The superior photocatalytic activity of RCQD/BOI is attributed to the established internal electric field that accelerates charge transfer and effectively separates the photogenerated e-h inside BiOI. Furthermore, through radical capture, electron paramagnetic resonance (EPR) experiments validated the photocatalytic mechanism of RCQD/BOI and revealed that h, O and OH are key reactants in the photocatalytic degradation process. This promising and sustainable approach for the synthesis of multicolor lignin-derived CQDs opens the avenue of high-value utilization of biomass resources, green production of CQDs nanomaterials, and efficient development of CQDs-based photocatalysts for wastewater treatment.

中文翻译：

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多色木质素衍生碳量子点：可控合成和光催化应用

利用生物质制造多色碳量子点（CQD）的成本效益高、高性能对其未来应用至关重要。木质素具有苯丙烷结构单元和丰富的官能团，是形成高质量CQD的可靠前体。在此，通过两步法成功制备了可再生木质素的CQD，并通过调节含氮酸性掺杂剂实现了CQD的可控制备，以发出蓝色、绿色、黄色和红色荧光。研究的荧光机制表明，随着石墨化程度和 C=O 表面基团数量的增加，木质素衍生的 CQD 的能带隙减小，发射波长红移。用蓝色CQD修饰为红色CQD的BiOI光催化剂的光吸收区域在红移方向上逐渐变宽。特别是，与纯BiOI（70.9％）相比，红色CQDs修饰的BiOI（RCQD / BOI）可以在光照射60分钟内去除94.7％的抗生素。 RCQD/BOI 优异的光催化活性归因于建立的内部电场，该电场加速电荷转移并有效分离 BiOI 内部的光生电子。此外，通过自由基捕获、电子顺磁共振（EPR）实验验证了RCQD/BOI的光催化机理，并揭示了h、O和OH是光催化降解过程中的关键反应物。这种有前景且可持续的多色木质素衍生 CQD 合成方法，为生物质资源的高价值利用、CQD 纳米材料的绿色生产以及基于 CQD 的废水处理光催化剂的高效开发开辟了道路。