Da Silva Eliana S, Moura Nuno M M, Coutinho Ana, Dražić Goran, Teixeira Bruno M S, Sobolev Nikolai A, Silva Cláudia G, Neves M Graça P M S, Prieto Manuel, Faria Joaquim L
Laboratory of Separation and Reaction Engineering, Laboratory of Catalysis and Materials (LSRE-LCM), Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias s/n, 4200-465, Porto, Portugal.
QOPNA, Department of Chemistry, Universidade de Aveiro, 3810-193, Aveiro, Portugal.
ChemSusChem. 2018 Aug 22;11(16):2681-2694. doi: 10.1002/cssc.201801003. Epub 2018 Aug 7.
A green, template-free and easy-to-implement strategy was developed to access holey g-C N (GCN) nanosheets doped with carbon. The protocol involves heating dicyandiamide with β-cyclodextrin (βCD) prior to polymerization. The local symmetry of the GCN skeleton is broken, yielding CxGCN (x corresponds to the initial amount of βCD used) with pores and a distorted structure. The electronic, emission, optical and textural properties of the best-performing material, C2GCN, were significantly modified as compared to bulk GCN. The spectroscopic and luminescent features of C2GCN show the characteristic π-π* electronic transition of GCN, accompanied by much stronger n-π* electronic transitions owing to the porous and distorted network. These new electronic transitions, along with the presence of additional carbon synergistically contributed to enhanced visible light absorption and restrained recombination of electron-hole pairs. Steady-state and time-resolved photoluminescence showed an effective quench of the fluorescence emission, accompanied by a decrease of fluorescence lifetime of C2GCN (2.20 ns) in comparison with GCN (5.85 ns), owing to the delocalization of electron and holes to new recombination centers. The photocatalytic activity of C2GCN was attributed to efficient charge carrier separation and improved visible-light absorbing ability. As result, C2GCN exhibited ∼5 times higher photocatalytic H generation under visible light than bulk GCN.
开发了一种绿色、无模板且易于实施的策略来制备掺杂碳的多孔g-CN（GCN）纳米片。该方案包括在聚合之前将双氰胺与β-环糊精（βCD）加热。GCN骨架的局部对称性被打破，生成具有孔隙和扭曲结构的CxGCN（x对应于所用βCD的初始量）。与块状GCN相比，性能最佳的材料C2GCN的电子、发射、光学和结构性质发生了显著改变。C2GCN的光谱和发光特征显示出GCN特有的π-π电子跃迁，由于多孔和扭曲的网络，还伴随着更强的n-π电子跃迁。这些新的电子跃迁以及额外碳的存在协同促进了可见光吸收的增强和电子-空穴对复合的抑制。稳态和时间分辨光致发光显示荧光发射有效猝灭，与GCN（5.85 ns）相比，C2GCN的荧光寿命缩短（2.20 ns），这是由于电子和空穴离域到新的复合中心。C2GCN的光催化活性归因于有效的电荷载流子分离和改善的可见光吸收能力。结果，C2GCN在可见光下的光催化产氢量比块状GCN高约5倍。
