2LiBH4–MgH2 nanoconfined into carbon aerogel scaffold impregnated with ZrCl4 for reversible hydrogen storage

• Nanoconfined 2LiBH4–MgH2 in carbon aerogel scaffold (CAS) doped with ZrCl4.
• Studies of hydride: ZrCl4-doped CAS weight ratio affecting on H2 desorption.
• Reduction of H2 desorption temperature and faster kinetics after ZrCl4 doping.
• Up to 97 and 93% of theoretical H2 capacity released and reproduced, respectively.

Nanoconfinement of 2LiBH4–MgH2 composite into carbon aerogel scaffold (CAS) impregnated with zirconium (IV) chloride (ZrCl4) for reversible hydrogen storage is proposed. Nanoconfined samples prepared with hydride:ZrCl4-doped CAS weight ratios of 1:1, 1:2, and 1:3 are prepared by melt infiltration technique. Successful nanoconfinement of all samples is confirmed and it is found that the sample with high content of hydride with respect to ZrCl4-doped CAS (1:1 weight ratio) shows partial pore blocking. The most suitable hydride:ZrCl4-doped CAS weight ratio providing the best performance based on dehydrogenation temperature and kinetics as well as hydrogen storage capacity is 1:2. Reduction of dehydrogenation temperature and faster kinetics are obtained after doping with ZrCl4. Up to 97 and 93% of theoretical hydrogen storage capacity are released and reproduced after four cycles of nanoconfined sample with ZrCl4 (1:2 weight ratio). Deficient hydrogen content with respect to theoretical capacity can be due to partial dehydrogenation during melt infiltration and formation of thermally stable [B12H12]2- phases during cycling.