Novel porous Al-based composites for improved Al–water reaction performances by spark plasma sintering

A series of novel porous hydrogen-generation materials with the formulae Al–(BiO)2CO3, Al–4BiNO3(OH)2·BiO(OH), and Al–Bi2(SO4)3 were synthesized by ball milling and spark plasma sintering (SPS). Their hydrogen-production properties were investigated. The results revealed that doping Al–(BiO)2CO3 in aluminium powder was the most effective for improving the hydrogen-generation performance. The hydrogen-conversion yield and maximum hydrogen-generation rate (MHGR) of the Al–(BiO)2CO3 block reached 94.9% and 384.6 mL g−1 min−1, respectively. Mechanism study indicated that (BiO)2CO3 decomposed into Bi2O3 and CO2, and the produced Bi2O3 could react with Al to produce Bi and Al2O3in situ during the SPS process. Herein, the produced CO2 could also form a large number of holes in the bulk sample under the action of sintering pressure to obtain the porous Al–(BiO)2CO3 composite. The hydrogen-generation performance of Al–(BiO)2CO3 was thus substantially enhanced under the synergistic effect of these factors.