Improving Carbon Nitride Photocatalysis by Supramolecular Preorganization of Monomers
Markus Antonietti a, Menny Shalom a, Christian Fettkenhauer a, Dieter Neher b, Sahika Inal b
a Max Planck Institute of Colloids and Interfaces - Potsdam, Research Campus Golm, D-14424 Potsdam, Germany
b University of Potsdam, Institute of Physics and Astronomy, Karl-Liebknecht-Str 24-25, Potsdam, 14476, Germany
Poster, Menny Shalom, 017
Publication date: 31st March 2013

Over the last few years Carbon Nitride (C3N4) has attracted widespread attention due to its outstanding catalytic and photo-catalytic activity. C3N4 materials have been found useful for many applications: as heterogeneous, metal-free photo-catalyst, for photo-degradation of pollutants, water splitting, and many more. Its unique optical, chemical and catalytic properties, alongside with its low price and remarkably high stability to oxidation (up to 550°C), make it a very attractive material for photo-catalytic applications. Nevertheless, it is still a standard problem of carbon nitride chemistry that only rather disorganized textures with small grain sizes are obtained. This is due to the fact that even though bulk C3N4 can be synthesized via simple condensing of monomers such as cyanamide (CA) or dicyandiamide (DCDA), as formed intermediates only react under solid state chemistry like conditions into the final 2-dimensionally condensed structure.

Here we report a new and simple synthetic pathway to form ordered open hollow structures of carbon nitride by using a Cyanuric acid-Melamine (CM) complex in ethanol as a starting product. A detailed analysis of the optical and photo-catalytic properties showed that optimum hollow carbon nitride structures are formed after 8 hours of condensation. For this condensation time, we find a significantly reduced fluorescence intensity and lifetime, indicating the formation of new non-radiative deactivation pathways, probably involving charge transfer processes. Enhanced charge transfer is as well seen from a drastic increase of the photo-catalytic activity in the photodegradation of RhB, which is shown to proceed via photo-induced hole transfer. Moreover, we showed that various CM morphologies can be obtained using different solvents, which leads to diverse ordered carbon nitride architectures. In all cases, the CM-C3N4s exhibited superior photo-catalytic activity compared to the bulk material. The utilization of cyanuric acid and melamine hydrogen-bonded complexes opens new opportunities for the significant improvement of carbon nitride synthesis, structure, optical properties towards an efficient photo-active material for catalysis.  

Shalom, M.; Inal,S.; Fettkenhauer,C.; Neher, D.; Antonietti, M. Improving Carbon Nitride Photocatalysis by Supramolecular Preorganization of Monomers. 2013, Submitted.
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