The hydrogen storage capacity of Al–Cu alloy with permeable alumina hydrogen permeation barrier (HPB) applied by plasma electrolytic oxidation (PEO)

The synchronous hydrogen permeable and environment protective PEO alumina hydrogen permeation barrier (HPB) coating was formed on aluminum - copper alloy hydrogen storage substrate with high sustainability and resilience at low temperatures and hydrogen desorption/absorption was characterized. The effects of tetragonal θ (Al2Cu) phase precipitation; formed and significantly increased within Al(Cu) matrix during standard T3 heat-treatment, on Al2CuH compound formation (with distorted tetragonal-based structure) and hydrogenation was analyzed. The decrease in permeation rate of PEO-HPBs was neglectable. The highly permeable barrier (with permeation resistance parameter near four) of alumina phases (α, γ) barely obstructed hydrogen inter-diffusion during hydrogenation/dehydrogenation steps and a hydrogen recovery of over 99% was achieved cyclic stability and long-term reversibility.