Zhao Ning, Zou Jianxin, Zeng Xiaoqin, Ding Wenjiang
National Engineering Research Center of Light Alloy Net Forming, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University Shanghai 200240 P. R. China
Shanghai Engineering Research Center of Mg Materials and Applications, School of Materials Science and Engineering, Shanghai Jiao Tong University Shanghai 200240 P. R. China.
RSC Adv. 2018 Mar 1;8(17):9211-9217. doi: 10.1039/c8ra00429c. eCollection 2018 Feb 28.
A new hydrogen storage composite containing NaBH and a 3d transition metal fluoride, 3NaBH/ScF, was synthesized ball milling. The composite shows no reaction during milling and its dehydriding process can be divided into three steps upon heating: (i) partial substitution of H by F in NaBH to form NaBH F at the early stage, releasing about 0.19 wt% of hydrogen; (ii) formations of NaScF, NaBF and ScB through the reaction between NaBH and ScF, with 2.52 wt% of hydrogen release and a dehydriding activation energy of 162.67 kJ mol H; (iii) further reaction of residual NaBH and NaScF to form NaF, B and ScB, with a dehydriding activation energy of 169.37 kJ mol H. The total hydrogen release of the composite reaches 5.54 wt% at 530 °C. The complete dehydrided composite cannot be rehydrogenated while the products after the second dehydriding step can be hydrogenated with an absorption activation energy of 44.58 kJ mol H. These results demonstrate that by adding 3d transition metal fluorides into NaBH, a partial reversibility in NaBH can be achieved.
通过球磨法合成了一种新型储氢复合材料，该材料包含硼氢化钠（NaBH）和一种3d过渡金属氟化物3NaBH/ScF。该复合材料在球磨过程中不发生反应，其脱氢过程在加热时可分为三个步骤：（i）在早期，硼氢化钠中的氢被氟部分取代，形成硼氢化钠氟化物（NaBH₂F），释放约0.19 wt%的氢；（ii）通过硼氢化钠与氟化钪（ScF）之间的反应形成氟化钠钪（NaScF）、硼氢化钠（NaBF）和硼化钪（ScB），释放2.52 wt%的氢，脱氢活化能为162.67 kJ/mol H；（iii）剩余的硼氢化钠与氟化钠钪进一步反应形成氟化钠（NaF）、硼（B）和硼化钪，脱氢活化能为169.37 kJ/mol H。该复合材料在530℃时的总氢释放量达到5.54 wt%。完全脱氢的复合材料不能再氢化，而第二步脱氢后的产物可以氢化，吸收活化能为44.58 kJ/mol H。这些结果表明，通过向硼氢化钠中添加3d过渡金属氟化物，可以实现硼氢化钠的部分可逆性。
