高效氨硼烷脱氢非贵金属催化剂的原子层沉积制备及性能研究

Ammonia-borane (NH3BH3, AB) complex has a hydrogen capacity of 19.6 wt %, making itself as an attractive candidate for on-board hydrogen-storage applications. One of the major challenges of the practical application of this system is to develop efficient, economical, and easily recyclable catalysts for further improving the kinetic and thermodynamic properties under moderate conditions. In this project, atomic layer deposition (ALD) technology will be introduced to prepare non-precious metal (Ni，Co，Fe) nanoclusters due to its great merits on the control of component , size and dispersion of nanoclusters in atomic-level. The effects of the component, size and dispersion of the non-precious matal nanoclusters on the catalytic performance for hydrolytic dehydrogenation of ammonia-borane will be investigated. And then, bimetal nanoclusters (Ni-Co, Ni-Fe, Co-Fe) will be fabricated and the non-precious metal nanoclusters will be coated by nanoporous Al2O3 or SiO2 via ALD technology in order to improve the activity and stability of the nanoclusters during the hydrolytic dehydrogenation process. The effects of component,size and structure of the bimetal nanoclusters, as well as the pore size and thickness of the coating layer, on the activity and stability for hydrolytic dehydrogenation of ammonia-borane will be investigated. Based on these above studies, the mechanism of the hydrolytic dehydrogenation of ammonia-borane will be discussed.

氨硼烷化合物具有超高的储氢容量（19.6 wt %），在车载储氢材料等领域具有广阔的应用前景。目前，制约其实际应用的关键因素之一是脱氢效率低，开发高效廉价的催化材料以促进氨硼烷在温和条件下快速水解脱氢具有重要意义。本项目拟利用原子层沉积(ALD)技术在控制纳米粒子组成、尺寸、分布及表面包覆等方面的独特优势，可控制备非贵金属（Ni，Co，Fe）纳米催化剂，研究粒子尺寸、分布及负载量等因素对其催化氨硼烷水解脱氢性能的影响规律；利用ALD技术可控制备双金属纳米粒子（Ni-Co、Ni-Fe、Co-Fe）、并在纳米粒子表面包覆多孔材料（Al2O3，SiO2），研究双金属纳米粒子组成、尺寸及结构、包覆层厚度和孔结构对催化剂催化氨硼烷脱氢活性和稳定性的影响；在上述研究基础上，进一步研究影响催化材料活性的关键因素以及活性中心的本质，并探讨催化反应机理，为设计和制备高效廉价的氨硼烷脱氢催化剂提供理论依据。

氨硼烷化合物具有超高的储氢容量（19.6 wt %），在车载储氢材料等领域具有广阔的应用前景。目前，制约其实际应用的关键因素之一是脱氢效率低，开发高效廉价的催化材料以促进氨硼烷在温和条件下快速水解脱氢具有重要意义。本项目利用原子层沉积(ALD)技术可控制备了分散性好，尺寸可控的CNTs负载的Ni，Co，Pt等纳米催化剂，并对其催化氨硼烷水解脱氢性能进行了系统研究，结果表明所制备的催化剂均表现出优异的催化活性。同时还利用ALD 技术可控制备了双金属纳米粒子（Ni-Pt、Co-Pt）催化剂，我们发现利用ALD引入微量的Pt（0.68 wt%)）后，Ni/CNTs的催化活性和稳定性进一步提高；并且CoOx和NiO修饰能显著提高Pt/CNTs的催化活性,表明两种金属间存在协同作用。本项目还研究了表面包覆层对催化剂活性和稳定性的影响，发现在Pt/CNTs催化剂表面包覆32.4 nm左右的多孔TiO2膜后催化剂的初始活性保持不变，但稳定性显著提高。本项目研究将为设计和制备高效廉价的氨硼烷脱氢催化剂提供理论和技术依据。