原子厚度铑基双金属纳米片制备、调控和甲醇电氧化性能研究

The anodic methanol oxidation reaction (MOR) is one of the key reactions in alkaline direct methanol fuel cell (ADMFC). Decreasing the overpotential of the MOR, increasing the electrocataytic activity and durability of electrocatalyst, and enhancing the utilization of noble metal are key issues in anodic electrocatalyst design for the ADMFC. Considering that the high intrinsic activity of Rh nanocrystals for the MOR in an alkaline medium, the particularly physical/chemical properties of the atomically thick two-dimensional nanomaterials, and the strong synergistic effect between the different elements, this research project aims at the exploration of the atomically thick two-dimensional Rh-based bimetallic nanosheets with high reactivity as Pt-alternative anodic electrocatalyst for the MOR in the ADMFC. In the project, the formation mechanism of the atomically thick two-dimensional Rh-based bimetallic nanosheets, the reaction pathway and catalytic mechanism of the MOR at the Rh metal surface, the inherent relationship beween the structural parameter/chemical compostion of Rh nanocrystals and their MOR activity will be investigated systemically. The research result of the project will contribute to the controllable synthesis of the atomically thick two-dimensional Rh-based bimetallic nanosheets and the development of Rh-based nanomaterials as new Pt-alternative electrocatalyst for the MOR, which may accelerate the commercialization of ADMFC.

阳极甲醇氧化反应(MOR)是碱性直接甲醇燃料电池(ADMFC)中重要的半反应之一。降低MOR过电势、增强电催化活性和稳定性、提高贵金属利用率是ADMFC阳极电催化剂研制的核心问题。基于碱性介质中Rh纳米晶对MOR高的本征电催化活性、超薄二维纳米材料独特的物理化学特性、不同化学组分间的协同作用，本项目拟合成原子厚度超薄Rh基双金属纳米片作为ADMFC阳极Pt替代电催化剂。掌握原子厚度超薄Rh基双金属纳米片的生成机理，明确MOR在Rh基电催化剂上的反应途径和催化机制，揭示原子厚度超薄Rh基双金属纳米片的结构参数、化学组成和MOR电催化性能之间的本征联系。本项目旨在解决原子厚度超薄Rh基双金属纳米片的可控合成，发展高活性Rh基纳米材料作为新型的Pt替代MOR电催化剂体系，助力ADMFC产业化。

阳极甲醇氧化反应(MOR)在电催化剂表面动力学迟缓和过电势高等问题严重制约碱性直接甲醇燃料电池(ADMFC)的商业化进程。本项目拟借助形态效应和组成效应合成一系列具有不同形态/化学组成/结构的Rh基纳米结构，进而研究其对MOR及其中间反应物种的电催化活性和稳定性。目前，我们已使用“限域生长湿化学合成法”、“氰胶还原法”、“自牺牲模板法”等合成方式成功制备出多种Rh和Rh基合金纳米结构(超薄纳米片、纳米管、纳米线等)。电化学测试结果显示，在碱性介质中，MOR在Rh纳米结构上的起始氧化电位远低于Pt电催化剂，表明MOR在Rh纳米结构上具有更小的过电势和更高的反应活性。同时，Rh纳米结构在碱性介质中对多种甲醇氧化中间产物(如甲醛、甲酸、一氧化碳等)也显示比Pt电催化剂更高的电催化活性，显示Rh纳米结构在碱性介质中是高性能MOR电催化剂。进一步借助双金属间的协同效应(双功能机理、电子效应、几何效应)，多种Rh基双金属纳米结构显示显著增强的MOR活性和稳定性。实验和理论计算结果均指出Rh基双金属纳米结构在碱性介质中对甲醇及其中间产物具有极佳的电催化活性和稳定性，是极具潜力的Pt替代电催化剂。