Title
ß‐Cyclodextrin as template‐free precursor to prepare holey C‐doped g‐C₃N₄ nanosheets with improved charge separation for efficient visible‐light photocatalytic hydrogen generation
Author
Eliana Sousa Da Silva, Nuno M. M. Moura, Ana Coutinho, Goran Goran Dražić, Bruno M. S. Teixeira, Nikolai A. Sobolev, Cláudia G. Silva, M. Graça, P. M. S. Neves, Manuel Prieto, Joaquim L. Faria
Year
2018
Journal
ChemSusChem
Abstract
A green, template‐free easy‐to‐implement strategy giving access to holey g‐C₃N₄ nanosheets doped with carbon is described. The protocol involves heating dicyandiamide with β‐cyclodextrin (βCD) prior to polymerization. By this approach, the local symmetry of g‐C3N4 skeleton is broken, thus yielding CxGCN (x corresponds to the initial amount of βCD used) with porous and a distorted structure. The electronic, emission, optical and textural properties of the best‐performing material, C2GCN, are thus greatly modified as compared to bulk g‐C₃N₄ (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 due to the porous and defect network. These new electronic transitions, along with the presence of additional carbon synergistically contribute to enhance visible light absorption and to restrain the recombination of electron‐hole pairs. Steady‐state and time‐resolved photoluminescence show an effective quench of the fluorescence emission, accompanied by a decrease of fluorescence lifetime (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 is consequently associated to the efficient charge carrier separation and to the higher visible‐light absorbing ability. As result, C2GCN exhibit a 5 times higher photocatalytic H₂ generation under visible light than bulk GCN.
Instrument
FP-8300
Keywords
Fluorescence, Photoluminescence, Nanostructures, Semiconductor, Kinetics, Materials, Optical properties