Hydrogen storage in carbon nanotubes and their composites
Practical hydrogen storage is critical for a fuel cell electric vehicle (FCEV), which is a key element of the hydrogen economy. Unfortunately, no current technologies in hydrogen storage can satisfy the requirements of a FCEV, e.g., fulfil the DOE (US Department of Energy) targets for hydrogen storage.
An on-board hydrogen storage system is the primary barrier that must be overcome to enable industry commercialisation of the FCEV. It requires a vehicle driving range of greater than 500 km, while meeting vehicle packaging, cost and performance requirements. Thus, new materials and approaches form the basis for research priorities both in Australia and worldwide such as the National Hydrogen Storage Project supported by DOE.
This project is aimed at the rational design and development of novel nanomaterials for on-board practical hydrogen storage in a FCEV. Carbon nanotubes (CNTs) have a unique tubular structure that facilitates hydrogen diffusion and transport. It is expected that CNTs will significantly enhance the hydrogen storage properties in materials that suffer from disadvantages such as high-temperature reactions and slow kinetics, (e.g., the re/dehydrogenation temperature and rate are the major limitations of the application of Mg-based materials for hydrogen storage).
Major achievements
Continuing in the research success of previous years, significant progress in enhancing hydrogen storage properties in Mg by CNTs and other catalysts has been achieved. In 2008, we presented the catalytic mechanism of metal oxides (V2O5 as an example) by theoretical studies (Appl Phys Lett 2008, 92, 163106) that demonstrated our hypothesis of such mechanisms in experimental observations (JACS 2007, 129, 15650); We also were the first to develop a diffusion model to calculate the diffusion coefficients of hydrogen in magnesium hydrides with CNTs additives and thus investigated the effect of grain size on hydrogenation of Mg at the nanoscale (J Mater Res 2008, 23, 336). The hydrogenation properties in Mg enhanced by catalytic effects and in nano-carbon have also been investigated and appeared in the book series Carbon Nanomaterials for Clean Energy Hydrogen System, Eds: B. Baranowski, 2008, pp. 233-240; 497-502, Springer. Due to our experience to this field, we were invited to present a review article in Mg-based materials for hydrogen storage (Chn. Sci. Bulletin, 2008, 53, 2421).
Future plans and directions
In the near future, in addition to the continuing research on the Mg-NanoCarbon systems for hydrogen storage, we will develop CNTs composite materials with other systems such as complex hydrides (LiBH4 and LiNH2 as an example) with very high hydrogen capacity and ammonia borane that can release hydrogen at a very low temperature.
Collaborations
Prof Huiming Cheng, Institute of Metal Research, Chinese Academy of Science, China
Prof Zhengxiao Guo, University College, London, UK
Prof Dongyuan Zhao, Fudan University, China
Prof Min Zhu, South China University of Technology, China
