碳量子点修饰g-C3N4/SnO2复合材料光催化性能

以四氯化锡五水合物、乙二醇和氨水为原料，在微波辅助水热条件下快速合成氧化锡纳米颗粒，以尿素 为前体在马弗炉中退火得到g-C₃N₄，使用柠檬酸和乙二胺为原料水热合成碳量子点。室温下，将碳量子点/ g-C₃N₄/SnO₂在通风橱中进行搅拌得到碳量子点负载的氮化碳/氧化锡复合材料。通过透射电子显微镜（TEM）、 X射线衍射（XRD）、氮气吸附-解吸等温线（BET）、紫外-可见分光光度计（UV-vis）、电子自旋（顺磁）共振波谱仪（ESR）对复合材料的形貌、结构特征、吸光度和光催化过程中的活性物质等进行表征和分析，并通过在紫外光下降解罗丹明B（RhB）测试样品的光催化性能。试验结果表明，紫外-可见分光光谱吸收边缘的红移说明碳量子点负载后能提高复合材料在可见光区域的响应，光催化试验表明碳量子点负载能提高g-C₃N₄/SnO₂复合材料的光催化性能，当碳量子点负载量为7%时复合材料的降解效率最高，在3h内对RhB的降解效率为97%。此外，微波辅助水热法能在短时间内大量合成氧化锡纳米颗粒，且氧化锡纳米颗粒具有较小的晶粒尺寸（8.5nm），可以高效制备并应用于环保领域。

Photocatalytic performance of carbon quantum dots modified g-C3N4/SnO2 composites

Using tin tetrachloride pentahydrate, ethylene glycol and ammonia as raw materials, tin oxide nanoparticles were rapidly synthesized under microwave-assisted hydrothermal conditions. Urea was used as a precursor to obtain g-C₃N₄ in a muffle furnace. Hydrocarbon-synthesized carbon quantum dots were prepared from citric acid and ethylenediamine, and finally stirred in a fume hood to obtain carbon quantum dot-loaded carbon nitride/tin oxide composites. TEM, X-ray diffraction (XRD), nitrogen adsorption-desorption isotherm (BET), ultraviolet-visible spectrophotometer (UV-vis) and electron spin (paramagnetic) resonance spectrometer (ESR) were used to characterize the morphology, structural characteristics, absorbance of the composite and characterization and analysis of active substances in the process of photocatalysis. The photocatalytic performance of the samples was tested by degrading rhodamine B (RhB) under ultraviolet light. The experimental results found the red shift of the absorption edge of the ultraviolet-visible spectroscopic spectrum, indicating that the loaded carbon quantum dots can improve the response of the composite in the visible light region. The photocatalytic experiments showed that the loaded carbon quantum dots can improve the photocatalysis of the g-C₃N₄/SnO₂ composite performance. When the load of carbon quantum dots was 7%, the degradation efficiency of composites was the highest and the degradation efficiency of RhB under 3h was 97%. In addition, the microwave-assisted hydrothermal method can synthesize a large amount of tin oxide nanoparticles in a short time and the tin oxide nanoparticles had a small grain size (8.5nm), which can be efficiently prepared and applied in the field of environmental protection.