Enhancing Hydrogen Storage in Carbon Nanostructures

增强碳纳米结构中的储氢能力这项提案的重点是在基本分子水平上提高碳纳米结构中储氢的知识基础。氢作为燃料的使用是有限的，部分原因是它的储存和运输存在严重问题。因此，迫切需要吸附大量氢的材料。碳纳米材料独特的吸氢特性使其非常适合作为储氢器件。虽然碳纳米管、碳纳米角和多孔碳在概念上有相当大的前景，但到目前为止，实验结果还不那么令人信服，这强烈表明，为了实现商业可行性，可能需要对结构进行一些修改。例如，已发现目标吸附剂需要极高的表面积才能接近适当的存储目标，这使得多层吸附成为必要。在他们提出的工作中，研究人员计划：(1)利用分子动力学模拟系统地评估各种碳纳米结构的氢吸附限制，并研究如何通过金属封装等修饰进一步增强这些限制；(2)进行相应的并行实验研究，以辅助和验证其模拟。金属颗粒包封有望增加碳纳米结构的储氢能力。在分子动力学模拟中，研究人员计划研究(1)压力的影响；(2)温度;(3)纳米管（扶手状、之字形或手性）和纳米纤维（管状、血小板状或人字形）结构；(4)金属粒子包封对碳纳米结构储氢的影响。他们将合成各种石墨碳纳米结构，其中一些将包含封装的金属颗粒，并进行一系列实验来研究这些和市售纳米结构的储氢能力。他们的分子模拟研究将为补充实验研究确定最有希望的结构和组成。该项目将产生更广泛的重大影响。由于继续使用化石燃料会对环境造成相当大的负面影响，而且未来的可得性有限，因此迫切需要开发氢等替代燃料。在汽车中使用氢还必须克服一些重大挑战，其中一些是由于存储限制。如果能克服这些问题，氢作为燃料的广泛使用将对全球经济产生巨大影响。该项目还具有合成新型碳纳米结构的潜力，例如，封装金属纳米颗粒。例如，对氧化敏感的金属可以有效地储存在纳米管中，各种催化剂也可以。这种横切效应可以导致纳米反应器的发展。尽管对碳纳米结构的研究是一个快速发展的领域，但由于缺乏经济批量生产这种材料的方法，商业化受到了阻碍。该项目将包括一名博士生和本科生的研究培训。

ENHANCING HYDROGEN STORAGE IN CARBON NANOSTRUCTURESIshwar K. Puri & Sohail MuradUniversity of Illinois at ChicagoThis proposal focuses on improving the knowledge base for hydrogen storage in carbon nanostructures at the fundamental molecular level. The use of hydrogen as a fuel is limited, in part because of serious problems with its storage and delivery. Materials that adsorb significant quantities of hydrogen are therefore urgently needed. The special hydrogen adsorbing characteristics of carbon nanomaterials make them well suited as hydrogen storage devices. While carbon nanotubes, carbon nanohorns and porous carbon show considerable conceptual promise, experimental results have not been as convincing thus far, strongly suggesting that some modification in the structure may be required for commercial viability. For instance, target adsorbents have been found to require extremely high surface areas to approach appropriate storage targets making multilayer adsorption necessary. In their proposed work, the investigators plan to: (1) systematically evaluate the hydrogen adsorption limitations of various carbon nanostructures using molecular dynamics simulations and examine how these can be further enhanced with modifications such as metal encapsulation; and (2) conduct a corresponding parallel experimental investigation to aid and validate their simulations. Metal particle encapsulation shows promise to augment the hydrogen storage capacity of carbon nanostructures. In their molecular dynamics simulations the investigators plan to investigate the effects of (1) pressure; (2) temperature; (3) nanotube (armchair, zigzag or chiral) and nanofiber (tubular, platelet or herringbone) structure; and (4) metal particle encapsulation on hydrogen storage in carbon nanostructures. They will synthesize various graphitic carbon nanostructures, some of which will contain encapsulated metal particles and conduct a series of experiments to investigate the hydrogen storage capacities of these and commercially available nanostructures. Their molecular simulation studies will identify the most promising structures and compositions for the complementary experimental studies. The project will have significant broader impact. There is a pressing need to develop alternate fuels, such as hydrogen, because of the considerable negative environmental impact from the continued use of fossil fuels and their limited future availability. There are significant challenges that must be overcome for hydrogen usage in automobiles, some due to storage limitations. If these can be overcome, the widespread use of hydrogen as a fuel will have an enormous influence on the global economy. This project also has the potential for synthesizing novel carbon nanostructures, e.g., with encapsulated metal nanoparticles. For instance, metals that are sensitive to oxidation can be stored efficiently inside a nanotube, as could various catalytic agents. This crosscutting effect can lead to the development of nanoreactors. Although research on carbon nanostructures is a fast-moving field, commercialization is hampered by the lack of methods to economically produce the material in bulk. The project will involve the research training of a PhD student as well as undergraduate researchers.