Carbon-based electrode materials have been widely used for many years for electrochemical charge storage, energy generation, and catalysis. We have developed an electrode material with high specific capacitance by entrapping graphite nanoparticles into a sol-gel network. Films from the resulting colloidal suspensions were highly porous due to the removal of the entrapped organic solvents from sol-gel matrix giving rise to high Brunauer-Emmett-Teller (BET) specific surface areas (654 m(2)/g) and a high capacitance density ( approximately 37 F/g). An exponential increase of capacitance was observed with decreasing scan rates in cyclic voltammetry studies on these films suggesting the presence of pores ranging from micro (< 2 nm) to mesopores. BET surface analysis and scanning electron microscope images of these films also confirmed the presence of the micropores as well as mesopores. A steep drop in the double layer capacitance with polar electrolytes was observed when the films were rendered hydrophilic upon exposure to a mild oxygen plasma. We propose a model whereby the microporous hydrophobic sol-gel matrix perturbs the hydration of ions which moves ions closer to the graphite nanoparticles and consequently increase the capacitance of the film.

中文翻译：

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包埋在二氧化硅基质中的碳纳米颗粒的电化学性质

多年来，碳基电极材料已广泛用于电化学电荷存储、能量产生和催化。我们通过将石墨纳米颗粒捕获到溶胶-凝胶网络中，开发了一种具有高比电容的电极材料。由于从溶胶-凝胶基质中去除了夹带的有机溶剂，从而产生高布鲁诺-埃米特-特勒 (BET) 比表面积 (654 m(2)/g) 和高电容密度（大约 37 F/g）。在对这些薄膜的循环伏安法研究中，随着扫描速率的降低，观察到电容呈指数增加，这表明存在从微孔 (< 2 nm) 到中孔的孔。这些薄膜的 BET 表面分析和扫描电子显微镜图像也证实了微孔和中孔的存在。当薄膜在暴露于温和的氧等离子体时变得亲水时，观察到极性电解质的双电层电容急剧下降。我们提出了一种模型，其中微孔疏水性溶胶-凝胶基质会扰乱离子的水合作用，从而使离子更靠近石墨纳米颗粒，从而增加薄膜的电容。