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PtNi@ZIF-8 nanocatalyzed high efficiency and complete hydrogen generation from hydrazine borane: origin and mechanistic insight
Journal of Materials Chemistry A ( IF 11.9 ) Pub Date : 2022-08-01 , DOI: 10.1039/d2ta04411k
Didier Astruc , Yufeng Wu , Changlong Wang , Xiang Liu

The rational design of highly efficient nanocatalysts and understanding of the hydrogen generation process for selective and complete decomposition of hydrazine borane (HB) remain challenging. Here, a series of monodispersed, ultrasmall, highly efficient PtxNiy alloyed nanoparticles were prepared using ZIF-8 as the MOF template. Upon scrutinizing the optimal Pt, Ni and support proportions, remarkable synergy of volcano-type is disclosed between these two metals in their alloy and with the ZIF-8 support. The high catalyst efficiency with complete gas evolution is among the best ever recorded, also showing promising utilization of this catalyst in other tandem reactions involving hydrogen. The experimental and DFT simulation results indicate that alloying Pt with Ni in PtNi@ZIF-8 with an optimized surface d-band center optimizes absorption and activation of the HB molecule, thereby reducing the energy barrier of the hydrolysis of the BH3 group in HB. By systemically comparing the hydrolytic decomposition processes of HB over the nanocatalysts PtNi@ZIF-8 and RhNi@ZIF-8, the desorption of the borate is identified as the rate-determining step. In the following decomposition of the N2H4 moiety, the nanocatalyst PtNi@ZIF-8 always shows a smaller Gibbs free energy gap than RhNi@ZIF-8, rationalizing the faster kinetics for complete hydrogen evolution. The principle and results generated in the present study should contribute to optimizing the design of highly efficient nanocatalysts for hydrogen generation from hydrogen storage materials.

中文翻译:

PtNi@ZIF-8纳米催化肼硼烷高效完全制氢:起源和机理洞察

高效纳米催化剂的合理设计和对肼硼烷(HB)选择性和完全分解的氢气生成过程的理解仍然具有挑战性。在这里,一系列单分散、超小、高效的 Pt x Ni y使用 ZIF-8 作为 MOF 模板制备合金纳米颗粒。在仔细检查最佳 Pt、Ni 和载体比例后,揭示了这两种金属在其合金中和与 ZIF-8 载体之间的显着火山型协同作用。具有完全气体逸出的高催化剂效率是有史以来最好的,也表明该催化剂在其他涉及氢气的串联反应中的应用前景广阔。实验和 DFT 模拟结果表明,在具有优化的表面 d 带中心的 PtNi@ZIF-8 中将 Pt 与 Ni 合金化可优化 HB 分子的吸收和活化,从而降低 BH 3水解的能垒HB组。通过系统比较 HB 在纳米催化剂 PtNi@ZIF-8 和 RhNi@ZIF-8 上的水解分解过程,硼酸盐的解吸被确定为速率决定步骤。在接下来的 N 2 H 4部分分解中,纳米催化剂 PtNi@ZIF-8 始终显示出比 RhNi@ZIF-8 更小的吉布斯自由能隙,从而合理化了更快的完全析氢动力学。本研究产生的原理和结果有助于优化储氢材料制氢的高效纳米催化剂的设计。
更新日期:2022-08-01
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