Carbon- and nitrogen-based porous solids: A recently emerging class of materials

Abstract

In this account, the emergence of a new family of porous solid-state materials based on carbon and nitrogen is discussed. This started with the observation that carbon nitride, a polymeric material with a composition close to C3N4, is not only unexpectedly thermally and chemically stable, but a semiconductor at the same time and able to catalyze a variety of chemical reactions, such as Diels-Alder cyclizations, oxidations, and photochemical water splitting. Carbon nitride is however already sufficiently reviewed but related materials with similar potential have essentially been not sufficiently covered. The remaining structures are manifold and cover the range from on the one hand covalent triazine frameworks (CTFs) as new semiconducting porous solid-state materials to the other porous nitrogen-doped carbons (NdCs) as catalysts which are known to be applicable in a variety of electrocatalytic reactions. CTFs are porous polymeric frameworks constituted of triazine rings and other aromatic rings. Chemical binding motifs and crystal structures can be used to control the band structure of such an (organic) solid-state material. Porous NdCs are usually made by adding nitrogen sources to classical carbonization recipes, and they are attracting a lot of interest because of their catalytic activity for electrochemical processes, such as oxygen reduction reaction (ORR). This account will summarize state-of-the-art work on those systems being next-generation catalysts for different kinds of reactions, which are affordable and high-performance catalysts with unique principle for emergence of catalytic activities, combining theoretical and experimental studies together with basic and applied science in a range of scientific fields from chemistry to physics. Indeed, the first exploration of the above materials as candidates for components of fuel cells and rechargeable metal-air batteries are discussed.