The production of hydrogen from water using a catalyst and solar energy is an ideal future energy source, independent of fossil reserves. For an economical use of water and solar energy, catalysts that are sufficiently efficient, stable, inexpensive and capable of harvesting light are required. Here, we show that an abundant material, polymeric carbon nitride, can produce hydrogen from water under visible-light irradiation in the presence of a sacrificial donor. Contrary to other conducting polymer semiconductors, carbon nitride is chemically and thermally stable and does not rely on complicated device manufacturing. The results represent an important first step towards photosynthesis in general where artificial conjugated polymer semiconductors can be used as energy transducers.

Graphitic carbon nitride, g-C 3 N 4 , can be made by polymerization of cyanamide, dicyandiamide or melamine. Depending on reaction conditions, different materials with different degrees of condensation, properties and reactivities are obtained. The firstly formed polymeric C 3 N 4 structure, melon, with pendant amino groups, is a highly ordered polymer. Further reaction leads to more condensed and less defective C 3 N 4 species, based on tri-s-triazine (C 6 N 7 ) units as elementary building blocks. High resolution transmission electron microscopy proves the extended two-dimensional character of the condensation motif. Due to the polymerization-type synthesis from a liquid precursor, a variety of material nanostructures such as nanoparticles or mesoporous powders can be accessed. Those nanostructures also allow fine tuning of properties, the ability for intercalation, as well as the possibility to give surface-rich materials for heterogeneous reactions. Due to the special semiconductor properties of carbon nitrides, they show unexpected catalytic activity for a variety of reactions, such as for the activation of benzene, trimerization reactions, and also the activation of carbon dioxide. Model calculations are presented to explain this unusual case of heterogeneous, metal-free catalysis. Carbon nitride can also act as a heterogeneous reactant, and a new family of metal nitride nanostructures can be accessed from the corresponding oxides.

Ordered and amorphous microporous polytriazine networks have been obtained from the trimerization of nitriles in a ZnCl2 melt at 400 °C (see structure of the polymer formed from 1,4‐dicyanobenzene; C gray, N blue). The materials are high‐performance polymers with very large surface areas and could find applications in gas storage, as sensors, or catalyst supports.

Heteroatom doped carbon materials represent one of the most prominent families of materials that are used in energy related applications, such as fuel cells, batteries, hydrogen storage or supercapacitors. While doping carbons with nitrogen atoms has experienced great progress throughout the past decades and yielded promising material concepts, also other doping candidates have gained the researchers' interest in the last few years. Boron is already relatively widely studied, and as its electronic situation is contrary to the one of nitrogen, codoping carbons with both heteroatoms can probably create synergistic effects. Sulphur and phosphorus have just recently entered the world of carbon synthesis, but already the first studies published prove their potential, especially as electrocatalysts in the cathodic compartment of fuel cells. Due to their size and their electronegativity being lower than those of carbon, structural distortions and changes of the charge densities are induced in the carbon materials. This article is to give a state of the art update on the most recent developments concerning the advanced heteroatom doping of carbon that goes beyond nitrogen. Doped carbon materials and their applications in energy devices are discussed with respect to their boron-, sulphur-and phosphorus-doping. Broader contextThe research and design of novel materials that are applicable in various energy devices represent one of the central and most thriving subjects within today's scientic work. The challenges do not only rely on the tremendous need to overcome traditional fossil fuel based energy recovery. While a lot of sustainable concepts already exist, these require the development of high performance materials that are able to cope with certain challenges, e.g. the dependence on highly expensive and rather not abundantly available noble metals, and also a lack of long term stability of those. Researchers have been carrying out numerous studies concentrating on nding alternative materials that can be applied in novel energy devices. Those alternative materials should most preferably be free of noble metals, avoid expensive precursor systems, be sustainable and not rely on the fossil energy sources that are to be replaced, and of course exhibit high activity in the devices they are designed for. One class of materials in whose development and understanding researchers have put strong effort is heteroatom-doped carbon materials. By heteroatom doping the properties are altered compared to crude carbon materials. The by far most intensely studied doping candidate is nitrogen, capable of not only increasing electric conductivity, but also the catalytic activity of carbons. Such N-doped carbons have advanced tremendously in the past few years, especially by proving their usefulness as electrocatalysts for the reduction of oxygen in fuel cell cathodes, or as electrode materials in supercapacitors. Meanwhile the spectrum of doping has been widened, and novel doped carbons have been reported, indicating the promising pote...