Abstract It is still a great challenge to synthesize carbohydrate-derived carbon dots (CDs) with long-wavelength emissions via a green and facile strategy. Herein, novel xylose-derived CDs with green-yellow emission (i.e., GY-CDs) were synthesized due to the doping effect of S and N elements, using a one-pot microwave-assisted hydrothermal method. The maximum emission located at 533 nm under 460 nm excitation, and the absolute quantum yield was as high as 42.44%. To unveil the emission mechanism, green and blue emissive xylose-derived CDs doped with N were also synthesized, respectively. Comparative study and various structural characterizations revealed that introducing protonated amino groups and sulfur-related moieties can narrow the energy gaps within surface states and contribute to the green-yellow emission. Further, the GY-CDs not only displayed transmutation of luminescent centers when the solution pH was above 6, but also exhibited ratiometric fluorescence changes in the pH range of 6–10 under 360 and 460 nm excitation, such distinctive dual-mode response, which together with excellent anti-interference, good water solubility, and outstanding photostability enables the prepared GY-CDs to be potential pH nanosensors.

中文翻译：

---

氮/硫共掺杂策略合成源自木糖的绿黄色碳点：在 pH 传感中的应用

摘要 通过绿色简便的策略合成具有长波长排放的碳水化合物衍生碳点（CDs）仍然是一个巨大的挑战。在此，由于 S 和 N 元素的掺杂效应，使用一锅微波辅助水热法合成了具有绿黄色发射的新型木糖衍生的 CD（即 GY-CD）。在460 nm激发下最大发射位于533 nm处，绝对量子产率高达42.44%。为了揭示发射机制，还分别合成了掺杂 N 的绿色和蓝色发射木糖衍生的 CD。比较研究和各种结构表征表明，引入质子化氨基和硫相关部分可以缩小表面态内的能隙，并有助于绿黄色发射。更多，