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Structural Insights into Poly(Heptazine Imides): a Light-Storing Carbon Nitride Material for Dark Photocatalysis

Title data

Schlomberg, Hendrik ; Kroeger, Julia ; Savasci, Goekcen ; Terban, Maxwell W. ; Bette, Sebastian ; Moudrakovski, Igor ; Duppel, Viola ; Podjaski, Filip ; Siegel, Renée ; Senker, Jürgen ; Dinnebier, Robert E. ; Ochsenfeld, Christian ; Lotsch, Bettina V.:
Structural Insights into Poly(Heptazine Imides): a Light-Storing Carbon Nitride Material for Dark Photocatalysis.
In: Chemistry of Materials. Vol. 31 (September 2019) Issue 18 . - pp. 7478-7486.
ISSN 1520-5002
DOI: https://doi.org/10.1021/acs.chemmater.9b02199

Abstract in another language

Solving the structure of carbon nitrides has been a long-standing challenge due to the low crystallinity and complex structures observed within this class of earth-abundant photocatalysts. Herein, we report on two-dimensional layered potassium poly(heptazine imide) (K-PHI) and its proton-exchanged counterpart (H-PHI), obtained by ionothermal synthesis using a molecular precursor route. We present a comprehensive analysis of the in-plane and three-dimensional structure of PHI. Transmission electron microscopy and solid-state NMR spectroscopy, supported by quantum-chemical calculations, suggest a planar, imide-bridged heptazine backbone with trigonal symmetry in both K-PHI and H-PHI, whereas pair distribution function analyses and X-ray powder diffraction using recursive-like simulations of planar defects point to a structure-directing function of the pore content. While the out-of-plane structure of K-PHI exhibits a unidirectional layer offset, mediated by hydrated potassium ions, H-PHI is characterized by a high degree of stacking faults due to the weaker structure directing influence of pore water. Structure-property relationships in PHI reveal that a loss of in-plane coherence, materializing in smaller lateral platelet dimensions and increased terminal cyanamide groups, correlates with improved photocatalytic performance. Size-optimized H-PHI is highly active toward photocatalytic hydrogen evolution, with a rate of 3363 mu mol/gh H-2 placing it on par with the most active carbon nitrides. K- and H-PHI adopt a uniquely long-lived photoreduced polaronic state in which light-induced electrons are stored for more than 6 h in the dark and released upon addition of a Pt cocatalyst. This work highlights the importance of structure- property relationships in carbon nitrides for the rational design of highly active hydrogen evolution photocatalysts.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: ISI:000487859200041
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Anorganic Chemistry III
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Anorganic Chemistry III > Chair Anorganic Chemistry III - Univ.-Prof. Dr. Jürgen Senker
Result of work at the UBT: Yes
DDC Subjects: 500 Science
500 Science > 540 Chemistry
Date Deposited: 15 Nov 2019 11:05
Last Modified: 15 Nov 2019 11:05
URI: https://eref.uni-bayreuth.de/id/eprint/53235