Hydrogen storage is crucial in applying hydrogen as an energy source, particularly for fuel-cell electric vehicles. There's considerable interest in exploring carbon-based materials for hydrogen storage due to their abundance, low cost, and eco-friendliness.

It's true that, compared to metal hydrides and other complex hydrides, carbon materials generally show lower hydrogen storage capacity. However, carbon materials such as activated carbon, carbon nanotubes, graphene, and fullerenes have still been studied for their potential in hydrogen storage.

Several factors make carbon materials attractive for hydrogen storage:

Now, coming back to your question: Will carbon materials' relatively lower volumetric hydrogen density limit their hydrogen storage development?

The answer might depend on the specific application. For some applications, like fuel cell vehicles, where space is limited, the volumetric density could indeed be a critical issue. But the gravimetric density might be more relevant for other applications where space is less of a concern.

As for your second question about coupling high-performance metal hydrides with carbon materials, this indeed could be a promising direction for research. Here are a few reasons:

Of course, this approach would also come with its own challenges, such as achieving uniform dispersion of the metal hydride in the carbon matrix, managing the volume changes of the metal hydride during hydrogen absorption/desorption, etc. Therefore, careful research and development would be needed.

In conclusion, despite some limitations, carbon materials still have considerable potential for hydrogen storage, and combining them with metal hydrides could be a promising research direction. But as always in research, it's crucial to stay open to new ideas and developments in the field, as the situation can change rapidly with new discoveries and technologies.

Yes of Course, carbon materials have prospects for hydrogen storage. Carbon-based materials such as activated carbon, carbon nanotubes, and graphene have been extensively studied for their potential in hydrogen storage due to their high surface area and ability to adsorb hydrogen molecules. However, further research is still needed to optimize their storage capacity and improve the kinetics of hydrogen uptake and release.