Tailoring reversible hydrogen storage performance of NaAlH4 through NiTiO3 nanorods

Abstract

Despite of the moderate working temperature and relatively high hydrogen capacity of NaAlH4, the slow H2 absorption and desorption kinetics and poor reversibility pose a major bottleneck hindering its practical application. Herein, porous NiTiO3 nanorods is constructed to tailor reversible hydrogen storage performance of NaAlH4. It is theoretically and experimentally demonstrated that the building of NiTiO3 nanorods effectively promotes the uniform distribution of catalytic Ni-based species and Ti-based species inside of NaAlH4 matrix that are capable of synergistically weakening Al-H bonds of NaAlH4. As a result, under the catalysis of porous NiTiO3 nanorods, the onset temperature for H2 desorption from NaAlH4 is decreased down to 89 °C, 91 °C lower than that of pure NaAlH4. In addition, NaAlH4 under the catalysis of porous NiTiO3 nanorods is capable of releasing 4.5 wt% H2 within 60 min, 3.8 and 0.9 wt% higher than that of NaAlH4 catalyzed by NiO and TiO2, respectively. More importantly, a reversible capacity of 4.6 wt% could be obtained for NaAlH4 under the catalysis of porous NiTiO3 nanorods after 5 cycles, corresponding to a capacity retention of 95%, while this value is significantly decreased to 42% for NaAlH4 without the addition of NiTiO3 nanorods. This work provides a new perspective for the development and design of high-performance catalysts for realizing reversible hydrogen storage of NaAlH4 under moderate condition.