Renewable, cheap and green biomass resources could meet the urgent need for producing graphene quantum dots (GQDs) on a large scale if high quality can be obtained. Here we report the gram-scale synthesis of single-crystalline GQDs derived from lignin biomass via a two-step method. The synthetic processes involve the oxidized cleavage step followed by the aromatic refusion step of alkali lignin molecules. Notably, this approach successively converts the biomass commonly considered as waste into a high-valued nanoscale product. The as-prepared single-crystalline GQDs, presenting a hexagonal honeycomb graphene network, are 1–3 atomic layers thick. Due to the bright fluorescence, up-conversion properties, long-term photostability, water solubility and biocompatibility, these high quality GQDs have potential to be excellent nanoprobes for multicolour bioimaging. The utilization of renewable biomass resources paves the way for green, low-cost and large-scale production of high quality GQDs and allows for the development of sustainable applications.

中文翻译：

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木质素生物质衍生的单晶石墨烯量子点的克级合成

如果能够获得高质量，可再生，廉价和绿色的生物质资源就可以满足大规模生产石墨烯量子点（GQD）的迫切需求。在这里我们报告通过木质素生物质衍生的单晶GQD的克级合成两步法。合成过程包括氧化裂解步骤，然后是碱性木质素分子的芳族回旋步骤。值得注意的是，该方法将通常被视为废物的生物质依次转化为高价值的纳米级产品。制备的具有六角形蜂窝石墨烯网络的单晶GQD的厚度为1-3个原子层。由于具有高亮的荧光，上转换特性，长期的光稳定性，水溶性和生物相容性，这些高质量的GQD有潜力成为用于多色生物成像的优秀纳米探针。可再生生物质资源的利用为绿色，低成本和大规模生产高质量GQD铺平了道路，并允许开发可持续的应用程序。