Carbon materials are, in general, very good absorbents of microwaves, i.e., they are easily heated by microwave radiation. This characteristic allows them to be transformed by microwave heating, giving rise to new carbons with tailored properties, to be used as microwave receptors, in order to heat other materials indirectly, or to act as a catalyst and microwave receptor in different heterogeneous reactions. In recent years, the number of processes that combine the use of carbons and microwave heating instead of other methods based on conventional heating has increased. In this paper some of the microwave-assisted processes in which carbon materials are produced, transformed or used in thermal treatments (generally, as microwave absorbers and catalysts) are reviewed and the main achievements of this technique are compared with those obtained by means of conventional (non microwave-assisted) methods in similar conditions.

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Resorcinol−formaldehyde carbon xerogels were prepared by means of two different synthesis methods: conventional (C) and microwave heating (MW). The influence of the heating method and the pH of the precursor solution on the textural and chemical properties of the carbon xerogels was investigated. It was found that by modifying the initial pH, it is possible to control the porosity of carbon xerogels independent of the heating method used. The electrochemical performance of a selection of synthesized carbon xerogels as electrode materials in electric double-layer capacitors was studied by cyclic voltammetry and charge/discharge experiments in an acidic medium (1 M H2SO4). The electrochemical performance of the carbon xerogels was compared to that of an activated carbon commercialized for this application (Norit Super DLC-50), and it can be seen that the carbon xerogels display similar specific capacitances to those of the commercial carbon. Moreover, carbon xerogels have a good cycle durability after 18 000 galvanostatic cycles, with a drop in specific capacitance of around 10%. This excellent cycle durability, together with the attractive properties of carbon xerogels and the saving of time and energy achieved with microwave-assisted synthesis, would make resorcinol−formaldehyde carbon xerogels promising materials for applications of an electric double-layer capacitor (EDLC).