Yan Zheng, Liu Yang, Zhang Leixin, Luan Jingde, Ke Xin
Liaoning Key Laboratory of Clean Energy and Institute of Clean Energy and Environmental Engineering, College of Energy and Environment, Shenyang Aerospace University, Shenyang 110034, P. R. China.
Langmuir. 2023 Sep 26;39(38):13705-13716. doi: 10.1021/acs.langmuir.3c01935. Epub 2023 Sep 12.
Constructing a nanostructure with a high surface area and regulating the band gap by nonmetallic doping are two effective methods for improving the photocatalytic activity of catalysts. A green template-free synthesis strategy of S-doped g-CN nanosheets is proposed via doping cystine as both the structural additive and S source. The features of S-doped samples (GCN-%) were systematically studied, including morphology and textural and photoelectric properties, which demonstrated that the introduction of cystine and simple manipulation of the preparation process could realize self-exfoliation of g-CN into nanosheets. The GCN-3% sample showed a surface area (131.88 m·g) 10.7 times enlarged compared with bulk g-CN (bulk-phase carbon nitride). Obvious redshift on the absorption edge induced by S doping can be observed, revealing a narrowed band gap and enhanced efficiency of photogenerated charge carrier separation. The DFT calculation results also verified that the introduced C-S site could lead to polarization of the local electric field and thus decrease the bandgap of g-CN nanosheets. GCN-3% showed a 99.3% photocatalytic degradation ratio of rhodamine B in 60 min at a rate of 0.17 min. By scavengers experiment revealed that superoxide anion (O) radicals and holes (h) were vital active components during the photocatalytic degradation.
构建具有高比表面积的纳米结构以及通过非金属掺杂调节带隙是提高催化剂光催化活性的两种有效方法。本文提出了一种以胱氨酸作为结构添加剂和硫源的绿色无模板合成策略来制备硫掺杂的石墨相氮化碳（g-CN）纳米片。系统研究了硫掺杂样品（GCN-%）的特性，包括形貌、结构和光电性能，结果表明引入胱氨酸并简单控制制备过程可实现g-CN自剥离成纳米片。GCN-3%样品的比表面积（131.88 m²·g⁻¹）相比块状g-CN（块状相氮化碳）增大了10.7倍。可以观察到硫掺杂引起的吸收边明显红移，这表明带隙变窄且光生载流子分离效率提高。密度泛函理论（DFT）计算结果也证实，引入的C-S位点可导致局部电场极化，从而降低g-CN纳米片的带隙。GCN-3%在60分钟内对罗丹明B的光催化降解率达到99.3%，降解速率为0.17 min⁻¹。通过清除剂实验表明，超氧阴离子（O₂⁻）自由基和空穴（h⁺）是光催化降解过程中的重要活性成分。
