Abstract
The development of the hydrogen economy is hampered by many issues connected with production, storage, distribution, and end-use. Although the hydrogen storage problem is particularly difficult, there are several attractive solutions under investigation, and chemical hydrogen storage (involving hydrogen-rich materials) has shown much promising properties. The boron-based materials are typical examples. They have high hydrogen densities, with up to four reactive B − H bonds. Most of the works have focused on dehydrogenation by hydrolysis or thermolysis so that it takes place in high extent in mild conditions. The first materials studied have been lithium borohydride, sodium borohydride, and ammonia borane. However, their development has been hindered by technical issues such as very high dehydrogenation temperatures, incomplete reaction, and purity of the produced hydrogen. To get round such problems, new materials have been proposed since the mid-2000s. Interestingly, those materials present attractive attributes, but also drawbacks. This is illustrated in the present review. We believe that boron-based hydrides have a significant potential in chemical hydrogen storage, but their implementation depends on the recyclability of the solid by-products; this seems to be the key factor.