Porous carbons are widely used in energy storage and gas separation applications, but their synthesis always involves high temperatures. Herein we electrochemically selectively extract, at ambient temperature, the metal atoms from the ternary layered carbides, Ti3 AlC2 , Ti2 AlC and Ti3 SiC2 (MAX phases). The result is a predominantly amorphous carbide-derived carbon, with a narrow distribution of micropores. The latter is produced by placing the carbides in HF, HCl or NaCl solutions and applying anodic potentials. The pores that form when Ti3 AlC2 is etched in dilute HF are around 0.5 nm in diameter. This approach forgoes energy-intensive thermal treatments and presents a novel method for developing carbons with finely tuned pores for a variety of applications, such as supercapacitor, battery electrodes or CO2 capture.

Die elektrochemisch induzierte Extraktion von Metallatomen aus den ternären Carbiden Ti3AlC2, Ti2AlC und Ti3SiC2 (MAX-Phasen) bei Raumtemperatur resultiert in der Bildung von amorphem Kohlenstoff mit engen Porengrößenverteilungen, wie Y. Gogotsi et al. in der Zuschrift auf S. 4977 ff. beschreiben. Dieser Ansatz vermeidet hohe Temperaturen und stellt eine neue Methode zur Synthese von Kohlenstoffmaterialien dar, die als Superkondensatoren, Batterieelektroden oder bei der CO2-Abscheidung eingesetzt werden können.

The present study provides a transmission electron microscopy investigation of iron/iron carbide phase transformations inside the multiwalled carbon nanotubes synthesized in a high isostatic pressure apparatus. Carbon nanotubes contained mostly Fe3C nanoparticles often with inclusions of one of the following: alpha-, gamma- or epsilon-iron. This evidences the ability of a nanotube to preserve the high-pressure (epsilon-iron) and high-temperature (gamma-iron) phases. We established the orientation relationships between iron phases, appeared to be in accordance with the ones theoretically predicted earlier.