A graphene doped carbon xerogel was synthesized by simply replacing the water (solvent) by an aqueous well-dispersed graphene oxide stable suspension in the precursor mixture used for the synthesis of the organic xerogel. During the carbonization of the organic xerogel, the graphene oxide sheets are reduced to graphene, which is embedded and well dispersed within the carbon xerogel matrix. Only a small minimum amount of graphene oxide is necessary to interconnect the graphene sheets throughout the carbon xerogel. This material has both a high porosity and an excellent electrical conductivity so that, when used as electrode in aqueous supercapacitors at high current density, it provides them with 25% more capacitance and 100% more power than the undoped carbon xerogels. The synthesis conditions, characteristics of the carbons and how these affect the electrical conductivity and performance of the materials in the supercapacitors are discussed.

An easy method to prepare carbon xerogels with tailored porous properties and high degree of graphitization is reported. A pristine carbon xerogel was obtained by microwave-assisted synthesis, which was then transformed into a graphitic carbon also via microwave heating. Graphitized carbon materials were obtained by using different microwave power densities and processing times, these parameters enabling the control of both the microporosity and the degree of graphitization of the initial carbon xerogel. This simple method has been found to improve the electrical conductivity of the pristine carbon xerogel up to 90%. The prepared graphitized materials were also evaluated as anode materials in lithium-ion batteries, resulting in stable cycle performances with specific capacities 70% higher than that of raw carbon xerogels.

A pristine carbon xerogel (AX) and two hybrid samples (AX-3% and AX-9%), with different graphene percentages (3 and 9 wt%), were synthesized using a fast and economical process. It was observed that graphene produces less shrinkage of the xerogel structure during synthesis. Moreover, the electrical conductivity of the materials increases linearly with the percentage of graphene added. Thus, AX-9% presents an electrical conductivity 135 and 321% greater than that of AX-3% and AX, respectively.As a result of the good pore size distribution and high electrical conductivity of AX-9%, when this material is used as electrode in supercapacitors, the resistance of the cell is reduced; therefore, better power densities are obtained. However, its capacitance values are the same as those of AX-3%. The performances of these materials as electrodes in supercapacitors were evaluated taking into account the influence of their porosity and electrical conductivity. Moreover, AX and AX-9% were subjected to mild oxidation with air to study the effect of air on the porosity, electrical conductivity, and performance of these treated samples as electrodes in supercapacitors.

A series of resorcinol formaldehyde based carbon xerogels were synthesized under identical conditions using different graphene oxide loads. The gelification reaction was carried out using a stable aqueous suspension of graphene oxide, yielding organic gels with graphene oxide concentrations ranging from 1.2 to 2.5%. After the carbonization, xerogels with medium surface area (650 m 2 /g) and a highly improved electrical conductivity were obtained. Specific capacitance of 120 F/g of one electrode at very high scan rate of 500 mV/s were achieved, as well as power densities above 30 kW/kg, which is a significant improvement of 180% with respect to the pristine xerogels. Carbonized xerogels were further steam activated to yield activated carbon xerogels with surface areas of up to 1800 m 2 /g. The use of activated xerogels improves slightly the specific capacitance at low scan rates only, and there is a sharp decrease above 20 mV/s, resulting in a worse performance than graphene oxide doped carbonized xerogels. The electrical conductivity of the graphene oxide-doped carbon xerogels decreases upon activation, which means that the influence of the electrical conductivity on a carbon xerogel is greater than its specific surface area, which it is is the first time it is observed for porous carbons.

Three different hybrid carbon xerogels containing Graphene Oxide (AXGO), Micronized Graphite (AXMG) and Carbon Black (AXCB) were synthesized using an easy, fast and affordable method. These three additives were initially selected to improve the electrical conductivity of the pristine activated carbon xerogel (AX) thus expecting to improve its performance in aqueous supercapacitors. Capacitances of the corresponding devices were measured as a function of current density and results of the high and low charge transfer regime of the supercapacitors were discussed separately. In both regimes, the differences observed between the hybrid electrodes were analyzed on the basis of the concurrent influence of the micro and mesoporosity, surface chemistry and electrical conductivity of the materials. Accordingly, even though all the hybrid carbon xerogels showed higher electrical conductivities, only AXGO rendered a better performance than AX, showing the highest capacitances in the whole interval of intensities studied. Consequently, at 16 A g-1 , the energy and power densities of the