As an emerging carbon nanomaterial, carbon dots (CDs) have superior prospects for applications in the area of photocatalysis due to their unique optical and electronic properties. In this study, a novel CDs modified g-C₃N₄/SnO₂ photocatalyst (CDs/g-C₃N₄/ SnO₂) was successfully synthesized by the thermal polymerization. Under visible light irradiation, the resulting CDs/g-C₃N₄/SnO₂ photocatalyst exhibited excellent photocatalytic activity for the degradation of indomethacin (IDM). It was demonstrated that a 0.5 % loading content of CDs led to the highest IDM degradation rate, which was 5.62 times higher than that of pristine g-C₃N₄. This improved photocatalytic activity might have been attributed to the unique up-conversion photoluminescence (PL) properties and efficient charge separation capacities of the CDs. Moreover, the combination of g-C₃N₄ with SnO₂ improved the separation of photoinduced carriers and augmented the specific surface area. Reactive species (RSs) scavenging experiments and electron spin resonance (ESR) revealed that superoxide radical anions (O₂^·−) and photogenerated holes (h⁺) played critical roles during the photocatalytic process. The results of the detection of H₂O₂ and ESR confirmed that CDs/g-C₃N₄/ SnO₂ was a Z-scheme heterojunction photocatalyst. Further, HRAM LC–MS/MS was employed to identify the byproducts of IDM, and the major IDM degradation pathways of the CDs/g-C₃N₄/SnO₂ photocatalyst were proposed. This study provides new ideas for the design of novel CDs modified photocatalysts for environmental remediation.

作为新兴的碳纳米材料，碳点（CD）由于其独特的光学和电子特性，在光催化领域具有广阔的应用前景。在这项研究中，通过热聚合成功地合成了一种新型的CDs改性的gC ₃ N ₄ / SnO ₂光催化剂（CDs / gC ₃ N ₄ / SnO ₂）。在可见光照射下，得到的CDs / gC ₃ N ₄ / SnO ₂光催化剂对吲哚美辛（IDM）的降解表现出优异的光催化活性。结果表明，0.5％的CD负载量导致最高的IDM降解率，是原始gC ₃ N _4的5.62倍。这种提高的光催化活性可能归因于CD独特的上转换光致发光（PL）特性和有效的电荷分离能力。此外，gC ₃ N ₄与SnO ₂的组合改善了光诱导载流子的分离并增加了比表面积。反应物种（RSs）清除实验和电子自旋共振（ESR）显示超氧自由基阴离子（O ₂^·-）和光生空穴（h ⁺）在光催化过程中起关键作用。H ₂ O ₂和ESR的检测结果证实CDs / gC ₃ N ₄ / SnO ₂是Z-方案异质结光催化剂。此外，HRAM LC-MS / MS用于鉴定IDM的副产物，并提出了CDs / gC ₃ N ₄ / SnO ₂光催化剂的主要IDM降解途径。这项研究为设计用于环境修复的新型CD改性光催化剂提供了新思路。