Division of Fuels and Power Technology, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
J Am Chem Soc. 2009 Nov 18;131(45):16493-9. doi: 10.1021/ja9054838.
The influence of nitrogen doping on the hydrogen uptake and storage capacity of high surface area carbon materials is presented in this report. To generate suitable study materials, we have exploited the relationship between synthesis conditions and textural properties of zeolite-templated carbons to generate a range of high surface area carbons with similar pore size distribution but which are either N-doped or N-free. For N-doped carbons, the nitrogen content was kept within a narrow range of between 4.7 and 7.7 wt %. The carbon materials, irrespective of whether they were doped or not, exhibited high surface area (1900-3700 m(2)/g) and pore volume (0.99 and 1.88 cm(3)/g), a micropore surface area of 1500-2800 m(2)/g, and a micropore volume of 0.65-1.24 cm(3)/g. The hydrogen uptake varied between 4.1 and 6.9 wt %. We present experimental data that indicates that the effect of N-doping on hydrogen uptake is only apparent when related to the surface area and pore volume associated with micropores rather than total porosity. Furthermore, by considering the isosteric heat of hydrogen adsorption and excess hydrogen uptake on N-free or N-doped carbons, it is shown that N-doping can be beneficial at lower coverage (low hydrogen uptake) but is detrimental at higher coverage (higher hydrogen uptake). The findings are consistent with previous theoretical predictions on the effect of N-doping of carbon on hydrogen uptake. The findings, therefore, add new insights that are useful for the development of carbon materials with enhanced hydrogen storage capacity.
本文介绍了氮掺杂对高比表面积碳材料吸氢和储氢能力的影响。为了生成合适的研究材料，我们利用沸石模板碳的合成条件与结构特性之间的关系，生成了一系列具有相似孔径分布但氮掺杂或未掺杂的高比表面积碳材料。对于氮掺杂碳，氮含量保持在 4.7 到 7.7wt% 的窄范围内。无论是否掺杂氮，这些碳材料都表现出高比表面积（1900-3700m2/g）和孔体积（0.99 和 1.88cm3/g）、微孔表面积 1500-2800m2/g 和微孔体积 0.65-1.24cm3/g。吸氢量在 4.1 到 6.9wt%之间。我们提供的实验数据表明，氮掺杂对吸氢的影响仅在与微孔相关的比表面积和孔体积而不是总孔隙率相关时才明显。此外，通过考虑无氮或氮掺杂碳上的氢气吸附等容热和过量吸氢，表明氮掺杂在低覆盖率（低吸氢量）时是有益的，但在高覆盖率（高吸氢量）时是有害的。这些发现与先前关于氮掺杂对碳吸氢的理论预测一致。因此，这些发现为开发具有增强储氢能力的碳材料提供了新的见解。
