Functional carbon nitride materials — design strategies for electrochemical devices

Kessler, F. K.; Zheng, Y.; Schwarz, D.; Merschjann, C.; Schnick, W.; Wang, X.; Bojdys,* M. J. Nature Reviews Materials 2017, Article number: 17030 (2017), DOI: 10.1038/natrevmats.2017.30

In the past decade, research in the field of artificial photosynthesis has shifted from simple, inorganic semiconductors to more abundant, polymeric materials. For example, polymeric carbon nitrides have emerged as promising materials for metal-free semiconductors and metal-free photocatalysts. Polymeric carbon nitride (melon) and related carbon nitride materials are desirable alternatives to industrially used catalysts because they are easily synthesized from abundant and inexpensive starting materials. Furthermore, these materials are chemically benign because they do not contain heavy metal ions, thereby facilitating handling and disposal. In this Review, we discuss the building blocks of carbon nitride materials and examine how strategies in synthesis, templating and post-processing translate from the molecular level to macroscopic properties, such as optical and electronic bandgap. Applications of carbon nitride materials in bulk heterojunctions, laser-patterned memory devices and energy storage devices indicate that photocatalytic overall water splitting on an industrial scale may be realized in the near future and reveal a new avenue of ‘post-silicon electronics’.

DOI: 10.1038/natrevmats.2017.30

Anionic silicate organic frameworks constructed from hexacoordinated silicon centres

Roeser,* J.; Dragica, P.; Bojdys, M. J.; Fayon, P.; Trewin, A.; Fitch, A. N.; Schmidt, M. U.; Thomas,* A. Nature Chemistry 2017, Advance Article, DOI: 10.1038/NCHEM.2771

Crystalline frameworks composed of hexacoordinated silicon species have thus far only been observed in a few high pressure silicate phases. By implementing reversible Si–O chemistry for the crystallization of covalent organic frameworks, we demonstrate the simple one-pot synthesis of silicate organic frameworks based on octahedral dianionic SiO6 building units. Clear evidence of the hexacoordinated environment around the silicon atoms is given by 29Si nuclear magnetic resonance analysis. Characterization by high-resolution powder X-ray diffraction, density functional theory calculation and analysis of the pair-distribution function showed that those anionic frameworks—M2[Si(C16H10O4)1.5], where M = Li, Na, K and C16H10O4 is 9,10-dimethyl-2,3,6,7-tetraolatoanthracene—crystallize as two-dimensional hexagonal layers stabilized in a fully eclipsed stacking arrangement with pronounced disorder in the stacking direction. Permanent microporosity with a two-step filling process was evidenced by gas-sorption measurements. The negatively charged backbone balanced with extra-framework cations and the permanent microporosity are characteristics that are shared with zeolites.

DOI: 10.1038/NCHEM.2771