A balance between catalysis and nanoconfinement towards enhanced hydrogen storage performance of NaAlH4

• Synergistic effect of catalysis and nanoconfinement in improving hydrogen storage performance of NaAlH4 is balanced. • The peak temperature for the dehydrogenation of NaAlH 4 is reduced to 164 °C. • The reversible systematic hydrogen storage capacity of NaAlH 4 could reach 3.3 wt.% after 5 cycles. Owing to its favorable thermodynamics and high density, NaAlH 4 has been widely regarded as a potential hydrogen storage material, but its practical application is hindered by the sluggish kinetics, high operating temperature and poor cycling stability. Here, taking advantage of Co-doped nanoporous carbon scaffolds as structural host, we develop a new strategy to balance the synergistic effect between the catalytic role of Co nanoparticles and the nanoconfinement role of porous carbon scaffolds via the controllable etching of Co nanoparticles towards enhanced hydrogen storage performance of NaAlH 4 . The etching of Co nanoparticles creates extra void spaces nearby catalytically active Co nanoparticles, which not only exerts the catalytic effect of Co nanoparticles, but also improves the nanoconfinement role in maintaining the cycling stability towards increased loading ratio and hence high systematic capacity. Induced by this balanced synergistic effect, the peak temperature for the dehydrogenation of NaAlH 4 could be reduced to 164 °C, 97 °C lower than the bulk counterpart, even under an ultrahigh loading ratio of 67 %, and more importantly, the reversible systematic hydrogen storage capacity could still reach 3.3 wt.% after 5 cycles. This work opens up a new avenue to improve the hydrogen storage performance of various complex hydrides.