Preparation of an activated carbon artifact: oxidative modification of coconut shell-based carbon to improve the strength

Coconut shell-based activated carbon was oxidized in aq. H2SO4, HNO3 and H2O2 to induce surface oxygen functional groups on its surface and to increase the mechanical strength of the resultant activated carbon artifact with PVB as a binder. Although all oxidation was confirmed to significantly increase the strength, aq. H2O2 was found to be most effective, giving strength as high as 6000 kPa, which is believed to be sufficient for the electrode of an electric double layer capacitor (EDLC). The increase of CO2 evolving groups induced on the surface of activated carbon appears to be responsible for the strength increase. There was an optimum extent of oxidation for the strength as well as the performance of the electrode. Too much oxidation reduces the electrical conductivity of the activated carbon. Facile oxidation by aq. H2O2 can be recommended as a practical modification of the surface since it takes place safely below 100degreesC without releasing any harmful gas. (C) 2002 Elsevier Science Ltd. All rights reserved.