Iodide- mediated templating synthesis of highly porous rhodium nanospheres for enhanced dehydrogenation of ammonia borane
Iodide- mediated templating synthesis of highly porous rhodium nanospheres for enhanced dehydrogenation of ammonia borane
复制标题
碘化物介导的高多孔铑纳米球模板合成用于增强氨硼烷脱氢
DOI：
10.1039/c8ta09077g
复制
发表时间：
2018
影响因子：
11.9
通讯作者：
Qiu Shilun
中科院分区：
文献类型：
--
作者：
Zou Houbing;Jin Bo;Wang Runwei;Wu Yanbo;Yang Hengquan;Qiu Shilun
构建多孔结构是提高金属纳米粒子催化效率的有效途径。然而，制备具有高比表面积的良好限定的多孔金属纳米颗粒目前是一个巨大的挑战。在此，我们开发了一种新的碘化物介导的模板策略，用于制备具有极高表面积（高达100 m2 g-1）和可控纳米多孔结构的高度多孔铑纳米球（HPRhS）。该策略的关键是利用碘离子的强大螯合能力来增强表面活性剂与金属前体之间的相互作用。通过改变金属前体的浓度，可以高度调节颗粒的尺寸，随着颗粒尺寸的增加，蠕虫状介孔逐渐转变为径向有序的介孔阵列.通过这种方法也可以很容易地制备一种纳米结构的RhCo合金。HPRhS在氨硼烷甲烷解脱氢反应中表现出显著的催化活性和稳定性，远高于文献报道的Rh催化剂。即使在低温（0 °C）下也可以实现上级的H2生成速率。结果表明，碘离子不仅可以改善纳米孔结构，而且可以通过电子转移调节表面电子性质，导致表面Rh原子上负电荷的积累。这有利于含硼物种的脱附，从而避免中毒活性中心。
Constructing porous structures is an efficient approach to improve the catalytic efficiencies of metal nanoparticles. However, preparing well-defined porous metal nanoparticles with high surface areas is currently a great challenge. Herein, we developed a novel iodide-mediated templating strategy for preparing highly porous rhodium nanospheres (HPRhS) with an exceptionally high surface area (up to 100 m2 g−1) and controllable nanoporous structures. The key to this strategy involves capitalizing on the strong chelating capacity of iodide ions to enhance the interaction between the surfactant and metal precursor. The particle sizes were highly tunable by varying the concentration of the metal precursor and the worm-like mesochannels gradually transformed into a radially ordered mesopore array with the increase of particle sizes. A bimetal RhCo alloy nanostructure could be also easily prepared via this strategy. Importantly, the obtained HPRhS showed a remarkable catalytic activity and stability in methanolytic dehydrogenation of ammonia borane, much higher than those of the reported Rh catalysts. A superior H2 generation rate could be achieved even at low temperatures (0 °C). It was demonstrated that the iodide ions could not only improve the nanoporous structure but also modulate the surface electronic properties via electron transfer, leading to accumulation of negative charges on the surface Rh atoms. This was favorable for the desorption of B-containing species, thereby avoiding poisoning active sites.