Portal de Periódicos da CAPES

Carbon: The Sixth Element

2010; Volume: 22; Issue: 7 Linguagem: Inglês

10.1002/adma.200904091

1521-4095

Markus Antonietti, Kläus Müllen,

Diamond and Carbon-based Materials Research

Materials scientists and organic chemists will agree on little but will probably concur that carbon is one of the most intriguing elements in the Periodic Table. Sign of greatest wealth and symbol of persistence (diamond), carbon is at the same time one of the more abundant elements in the universe and on earth. Graphite was the first known semiconductor, coal the driver of industrial revolution, the excessive use of carbon fuels is outbalancing our climate, etc., etc. Carbon potentially forms many allotropes, two of which have been known from the beginning of science (diamond and graphite) and another two have been discovered in recent years (fullerenes and nanotubes), enflaming the imagination of chemists all over the disciplines. The newest revelation in carbon chemistry—the exfoliatation of single two-dimensional graphene sheets aided by progress in organic synthesis procedures—opened the pathway to carbon-based electrical engineering and electronics with materials characteristics that were unknown from ordinary metallic conductors.! Talking specifically about materials' properties, many other superlatives apply to carbon species: the highest hardness (diamond) and elongation modulus (carbon nanotubes), the highest electric and heat conductivities, an enormous chemical inertness (graphite), thermal insulation under extreme conditions (carbon nanofoams), but also highest sorption capacities (activated carbons). There is practically no discipline in the Olympics of materials where a carbon species cannot play a competitive role. A hardcore synthetic chemist targeting a well-defined hydrocarbon molecule, preferentially in solution, might tend to look down on carbon research with the suspicion that long-known species such as charcoal or carbon black are products of old-fashioned, backward methodologies. Today's carbon chemistry requires much more subtle approaches related to structural complexity; these include fullerene or nanographene synthesis, but also precursor- or template-determined pyrolysis and harsher methods such as chemical vapor deposition or laser ablation. Closely connected issues are rigorous structure elucidation at different length scales, often involving the solid state and its morphologies, and functional characterization including charge-, spin-, or mass transport and storage. The ability to master efficient carbon cycling and creative carbon chemistry will thus determine human fate in the 21st century, if even just elemental necessities of modern life are to be maintained. A carbon (coal or biomass)-based material can in principle be cheaper and more sustainable than the current petrochemical products, and carbon fixed in long-lasting materials is, from a different perspective, bound carbon dioxide taken out of the atmosphere, i.e., carbon-negative materials chemistry. Whether one looks at carbon materials as active device components, as efficient catalysts, or as a reservoir for gas storage, there is little doubt that they are at the center stage of energy-related technologies. This editorial therefore highlights the readiness of scientists to take on the pressing needs faced by our societies when struggling to secure their future and well-being. With all these options holding so many potentialities, it is therefore a timely endeavour to dedicate a theme issue of Advanced Materials to recent developments in carbon materials. We intended to cover the width of the field with contributions that range from the progress in rational organic synthesis of extended carbon structures to the design of controlled porosity within carbon monoliths (i.e., the chemistry of a pore). In the more process-oriented pathways towards functional carbon units, bond-to-bond control is essentially abandoned (“making black stuff”), but simplicity and morphology control will shift to the center of interest. And there is of course no generation of a specific carbon material without also dealing with its applications say in optoelectronics, for providing electric conductivity, or serving in more complex applications with a combination of required properties at the same time, such as implementation in lithium batteries. Another interesting aspect of our research is the passion found in many of the present articles: it seems that working intensely on the sixth element indeed induces polarization, not only at its interfaces. Black stuff is beautiful! May this Special Issue transfer at least some of that joy to the reader, making carbon an educated choice for the selection of the next-generation materials, and may this Special Issue also spur the imagination and creativity of readers that are still foreign to the field. There is much more to come and much more to do.