Nickel Decoration Promotes Pure Hydrogen Release from Sodium Zinc Borohydride

Sodium zinc borohydride (NaZn(BH4)3) is an attractive hydrogen storage material due to its ease of preparation and hydrogen release aligning well with the operational conditions of proton exchange membrane fuel cells. However, a critical limitation of NaZn(BH4)3 is the loss of boron as diborane (B2H6) during hydrogen release. Herein, this work presents a straightforward approach to address this challenge. NaZn(BH4)3 is stabilized in the form of nanorods and decorated with nickel (Ni) as a catalyst. Notably, Ni-decorated NaZn(BH4)3 exhibits pure hydrogen release at a significantly lower temperature (50 degrees C) compared to pristine material, which releases a substantial amount of B2H6 alongside hydrogen at 100 degrees C. In-depth structural analyses reveal that Ni decoration facilitates the decomposition of B2H6 (into B and H2) near the interfaces between the shell and borohydride core within the NaZn(BH4)3 nanorods. These findings pave the way for the development of novel strategies to achieve pure hydrogen generation from various mixed-metal complex hydrides. Nickel decoration in solid-state effectively suppresses the evolution of toxic diborane (B2H6) from sodium zinc borohydride (NaZn(BH4)3). The Ni-decorated material exhibits pure hydrogen release below 160 degrees C, a significant improvement compared to unmodified NaZn(BH4)3. Our analyses show that metallic Ni present on the borohydride surface functions as a catalyst and promotes B2H6 splitting into B and H2. image (c) 2024 WILEY-VCH GmbH