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

Abstract

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.