高稳定性低Pt合金纳米管阵列的可控合成及其氧还原催化性能

The low Pt alloy catalysts with advanced nanostructures have shown remarkable activity for oxygen reduction reaction (ORR). However, some adverse effects, such as the dissolution of metals, the poisoning of strongly adsorbed species and the corrosion of carbon supports, in proton exchange membrane fuel cells (PEMFCs) operation environments could result in the degradation of catalytic activity and stability, which still hinder their practical applications in PEMFCs. To overcome the above barriers, we propose an ingenious approach to enhance the electrocatalytic durability of low Pt alloy by designing nonmetal-doped Pt-transition metal-nonmetal alloy nanotube arrays composed of the homogeneous overlapped nanocrystals. In view of the self-supporting nanotube array structure can be easily overcome the disadvantages of using a carrier, in this project, the study will focus on: i) using nonmetal doping to enhance the degree of alloying of the low Pt alloy nanotube arrays and optimize the surface structure of nanoparticles; ii) using the strong interfacial interactions between the nanoparticles to weaken the adsorption strength of the poisoning species on the low Pt alloy nanotube arrays. Moreover, the project will also study the co-deposition mechanism of metal and nonmetal elements from the theoretical level, as well as the composition/structure-performance relationships between the nonmetallic doping concentration, surface & interface structures and the catalytic activity and structural stability of the low Pt alloy nanotube arrays. And then the kinetics of the ORR on Pt-transition metal-nonmetal alloy nanotube arrays will be studied to illustrate the mechanism and effects of nonmetal doping. As a result, a new class of low Pt alloy nanotube arrays catalysts with high stability will be designed and synthesized based on the above studies. The results will provide a novel design strategy to fabricate the ORR catalysts with excellent catalytic activity and durability, which will be of great realistic significance for accelerating the commercialization process of PEMFCs.

针对低Pt合金氧还原催化剂在酸性介质中易于遭受氧化溶解、强吸附物种毒化以及载体腐蚀等不利影响，从而导致其稳定性较差的难题，本项目提出利用非金属掺杂，并结合零维和一维纳米材料的结构优点，制备新型由纳米粒子均匀组装的自支撑Pt-过渡金属-非金属合金纳米管阵列作为高稳定性的氧还原催化剂。主要研究通过非金属掺杂实现对低Pt合金纳米管合金化程度的提高及其表面结构的优化，并研究纳米粒子间的强界面相互作用对毒化物种吸附强度的影响。本项目将从理论层面上探究金属和非金属元素的共沉积机理，以及不同非金属元素的掺杂浓度和表界面结构对低Pt合金纳米管阵列催化活性和结构稳定性的影响规律，阐明非金属元素掺杂影响其氧还原催化性能的内在机制，最终获得对氧还原反应兼具高催化活性和高稳定性的新型低Pt合金催化剂。该研究成果将为高效氧还原催化剂的设计提供新的思路，对加快质子交换膜燃料电池的商业化进程具有重要的现实意义。

针对电化学储能器件对高效电极材料的迫切需求，项目研究团队依托本项目，在燃料电池催化剂电极以及储能电极的一体化设计、制备以及结构和性能调控方面开展了系统的研究工作。创新性地提出了基于氧化锌纳米棒阵列的模板辅助电沉积法可控合成三维有序多孔低Pt催化剂电极的新思路，通过实现对Pt基金属纳米粒子的可控组装，显著提升了Pt电极的催化活性和利用率；进一步发展了模板辅助电沉积技术，成功实现了非金属元素磷对Pt及Pt基合金的高效掺杂，从而有效改善了Pt基催化剂电极的循环稳定性，其用于氧还原反应的单电极循环寿命达到上万次；并在此基础上，拓展研制了高选择性的氮还原催化剂，实现了常温常压下氮气的电化学还原合成氨，且库伦效率高达2.8%。此外，针对钠离子电池和柔性储能器件对电极材料的特殊需求，分别成功研制出了适用于钠离子扩散的多孔无定型碳电极材料，以及适用于可压缩器件的自支撑一体化多孔柔性电极。在本基金项目的资助下，共计在JACS、Adv. Mater.、Chem. Sci.、Small等国际著名学术期刊上发表SCI论文7篇，申请中国发明专利6件。