Ordered mesoporous carbon/fused silica composites

Abstract

A series of novel, dense, and interesting ordered mesoporous carbon (OMC)/fused silica composites with different carbon contents has been prepared by a controllable but simple sol-gel method followed by hot-pressing. In the as-sintered OMC/fused silica composites the carbon particles still exist in the form of perfectly ordered carbon nanowires. Conductivity measurements on the composites indicate that these novel composites are electrically conductive and have a typical percolation threshold of 3.5-5 vol% OMC. The electromagnetic interference (EMI) shielding efficiency (SE) of an OMC/fused silica composite containing 10 vol% OMC is as high as 40 dB in the X band which is higher than that of a carbon nanotube (CNT)/ fused silica composite with the same carbon content (∼30 dB). This indicates that these conductive OMC/fused silica composites are very suitable for an application as EMI shielding materials. Upon increasing the volume content of OMC in the composite the overall contribution as well as the increase rate of the microwave absorption are larger than those of the microwave reflection, which suggest that OMC/fused silica composites may also be promising electromagnetic (EM) wave absorbing materials. Based on the promising properties of these composites this work will hopefully lead to the development of new low-cost and highly efficient EMI shielding or EM wave absorbing materials. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA.