Influences of Ni-Co-B catalyst on the thermal decomposition of light-weight NaNH₂-NaBH₄ hydrogen storage material

NaNH₂ and NaBH₄ were utilized to prepare a composite hydrogen storage material, NaNH₂-NaBH₄. To improve the thermal decomposition kinetics of NaNH₂-NaBH₄, which is crucial for hydrogen-release performance, Ni-Co-B was selected as a catalyst. To prepare the catalyst-promoted light-weight hydrogen storage materials, a composite hydrogen storage system was synthesized via a ball milling method with NaNH₂, NaBH₄, and Ni-Co-B. X-ray diffraction patterns show that the crystal structure of the NaNH₂-NaBH₄ is well maintained after adding catalysts. In addition, Na₃BN₂ and metal Na were detected as by-products in the Ni-Co-B-promoted NaNH ₂-NaBH₄ (with a molar ratio of 2:1) after the thermal decomposition process. In addition, thermogravimetry-differential thermal analysis indicates that the main decomposition stages of the metal boride-promoted NaNH₂-NaBH₄ materials were split into three stages. Furthermore, the catalytic effects on the thermal decomposition kinetics were evaluated. The activation energy of the Ni-Co-B-promoted NaNH ₂-NaBH₄ below 250 °C is 99 kJ/mol, which is only 62.0% of that of pristine NaNH₂-NaBH₄ (2/1), implying better kinetics in the low temperature decomposition range.