Carbon materials have attracted intense interests as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost. Activated carbons produced by different activation processes from various precursors are the most widely used electrodes. Recently, with the rapid growth of nanotechnology, nanostructured electrode materials, such as carbon nanotubes and template-synthesized porous carbons have been developed. Their unique electrical properties and well controlled pore sizes and structures facilitate fast ion and electron transportation. In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-capacitance have been explored. They show not only enhanced capacitance, but as well good cyclability. In this review, recent progresses on carbon-based electrode materials are summarized, including activated carbons, carbon nanotubes, and template-synthesized porous carbons, in particular mesoporous carbons. Their advantages and disadvantages as electrochemical capacitors are discussed. At the end of this review, the future trends of electrochemical capacitors with high energy and power are proposed.

Surfactant-templated synthesis [1,2] has been a focus of materials science, because it provides a unique means to prepare a variety of ordered mesostructured materials with high surface areas and large, uniform pores. These materials have shown great promise for applications in physics, chemistry, and biology. [3][4][5][6][7][8][9] Different morphologies of mesoporous materials, such as spheres, films, monoliths, rods, and fibers, can all be controllably synthesized. [10,11] Among these, mesoporous thin films have attracted significant attention owing to their unique structures and functions. [12][13][14][15] Previously, ordered mesoporous silica films have been synthesized by selfassembly of silica precursors with surfactant templates at air-water [16] or water-oil interfaces, [17] or by using the evaporation-induced self-assembly (EISA) approach.[18] As the surfactant micelles tend to orient parallel to substrates to reduce the surface energy at interfaces, the mesochannels obtained are always oriented parallel to the film surfaces. [3,[19][20][21] Continuous mesoporous films with perpendicularly aligned channels have recently been prepared by guiding the self-assembly of block copolymers or gemini surfactants with organosilica. [22][23][24][25] However, the thermal and mechanical stability of the films are low, as the pore walls consist of polymers and organosilica. Substrate-templating growth strategies for controlling mesopore orientation based on pp or hydrophilic-hydrophobic interactions have been reported. [26][27][28][29][30] However, these methods require special substrates, such as pyrolytic graphite, anodic alumina with conical holes, or block polymer modified glass, and the alignment of the mesophases at their interface is generally of mixed orientation. Furthermore, perpendicular mesochannels have also been prepared by magnetic-field or electrochemically assisted methods. [31,32] However, these methods often require special equipment and complex processes, and the obtained films have poor regularity and low levels of mesochannel alignment. To date, the synthesis of films with mesopore channels perpendicular to a substrate is still a major challenge.The Stçber approach is a facile and effective method for the synthesis of uniform mesoporous silica nanospheres by a self-assembly process using silica precursors with surfactant templates in an aqueous ethanol solution.[33] The ordered mesochannels in these mesoporous silica nanospheres are often oriented radially to the particle surfaces, [34][35][36] which is an ideal pore arrangement for applications such as catalysis and selective adsorption. Herein, we demonstrate a simple Stçber-solution growth method for the synthesis of mesoporous silica thin films with continuous 2D-ordered mesochannels perpendicular to the substrate. This is accomplished by immersing the substrate into a Stçber solution containing cetyltrimethylammonium bromide (CTAB), tetraethoxysilane (TEOS), ethanol, and ammonia. Moreover, a new type of sandwichlike mesoporous silica film, w...

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We report for the first time the synthesis of free-standing mesoporous carbon films with highly ordered pore architecture by a simple coating-etching approach, which have an intact morphology with variable sizes as large as several square centimeters and a controllable thickness of 90 nm to ∼3 μm. The mesoporous carbon films were first synthesized by coating a resol precursors/Pluronic copolymer solution on a preoxidized silicon wafer and forming highly ordered polymeric mesostructures based on organic-organic self-assembly, followed by carbonizing at 600 °C and finally etching of the native oxide layer between the carbon film and the silicon substrate. The mesostructure of this free-standing carbon film is confirmed to be an ordered face-centered orthorhombic Fmmm structure, distorted from the (110) oriented body-centered cubic Im3̅m symmetry. The mesoporosity of the carbon films has been evaluated by nitrogen sorption, which shows a high specific BET surface area of 700 m(2)/g and large uniform mesopores of ∼4.3 nm. Both mesostructures and pore sizes can be tuned by changing the block copolymer templates or the ratio of resol to template. These free-standing mesoporous carbon films with cracking-free uniform morphology can be transferred or bent on different surfaces, especially with the aid of the soft polymer layer transfer technique, thus allowing for a variety of potential applications in electrochemistry and biomolecule separation. As a proof of concept, an electrochemical supercapacitor device directly made by the mesoporous carbon thin films shows a capacitance of 136 F/g at 0.5 A/g. Moreover, a nanofilter based on the carbon films has shown an excellent size-selective filtration of cytochrome c and bovine serum albumin.

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