Tailoring of nanoscale porosity in carbide-derived carbons for hydrogen storage
Tailoring of nanoscale porosity in carbide-derived carbons for hydrogen storage
复制标题
DOI：
10.1021/ja0550529
复制
发表时间：
2005-11-23
影响因子：
15
通讯作者：
Fischer, JE
中科院分区：
文献类型：
--
作者：
Gogotsi, Y;Dash, RK;Fischer, JE
储氢材料性能差一直阻碍着燃料电池汽车的发展。纳米级碳，特别是（活性碳，剥离石墨，富勒烯，纳米管，纳米纤维和纳米角），尚未实现其最初的承诺。在这里，我们表明，碳材料可以合理地设计用于H2存储。碳化物衍生碳（CDC）是一种未知的多孔碳，是通过高温氯化碳化物制备的。金属和类金属以氯化物的形式被去除，留下的是具有高达80%开孔体积的塌陷的非晶碳。孔隙率平均尺寸和尺寸分布、形状和总比表面积（SSA）的详细性质可以通过选择前体碳化物（组成、晶格类型）和氯化温度以高灵敏度进行调整。最佳温度是有界的氯化反应的热力学和动力学从下面和从上面的石墨化，这降低了SSA和引入H2吸附表面的结合能太低，是有用的。直觉上，不同尺寸和形状的孔不应该对氢存储做出相同的贡献。通过将孔性质与各种CDC的77 K H2等温线相关联，我们实验证实，重量储氢capacitynormalized总pore volumeis优化的材料，主要是微孔（0.1 nm），而不是介孔。因此，与理论预测一致，小孔的窄尺寸分布对于储存氢是期望的，而大孔仅降低体积储存容量。
The poor performance of hydrogen storage materials continues to hinder development of fuel cell-powered automobiles. Nanoscale carbons, in particular (activated carbon, exfoliated graphite, fullerenes, nanotubes, nanofibers, and nanohorns), have not fulfilled their initial promise. Here we show that carbon materials can be rationally designed for H2storage. Carbide-derived carbons (CDC), a largely unknown class of porous carbons, are produced by high-temperature chlorination of carbides. Metals and metalloids are removed as chlorides, leaving behind a collapsed noncrystalline carbon with up to 80% open pore volume. The detailed nature of the porosityaverage size and size distribution, shape, and total specific surface area (SSA)can be tuned with high sensitivity by selection of precursor carbide (composition, lattice type) and chlorination temperature. The optimum temperature is bounded from below by thermodynamics and kinetics of chlorination reactions and from above by graphitization, which decreases SSA and introduces H2-sorbing surfaces with binding energies too low to be useful. Intuitively, pores of different size and shape should not contribute equally to hydrogen storage. By correlating pore properties with 77 K H2isotherms from a wide variety of CDCs, we experimentally confirm that gravimetric hydrogen storage capacitynormalized to total pore volumeis optimized in materials with primarily micropores (∼1 nm) rather than mesopores. Thus, in agreement with theoretical predictions, a narrow size distribution of small pores is desirable for storing hydrogen, while large pores merely degrade the volumetric storage capacity.