超细纳米Pt/过渡金属氮化物复合材料的可控合成及其电催化氧还原性能研究

Noble-metal Pt is considered as an important electrocatalyst for oxygen reduction reaction (ORR). Solving the issue of high cost and poor stability of Pt electrocatalyst is of great significance for achieving the global sustainable development of renewable energy. Forming nanocomposites by assembling Pt electrocatalyst with reduced size onto support can efficiently increase the atomic utilization. However, how to modulate the Pt nanostructure and Pt-support interaction to further improve their activity and stability still remains challenging. This project proposes a novel in situ adhesion-reducing growth mechanism to firmly anchor ultrathin Pt nanostructures onto the surface of transition-metal nitrides (TMNs), and the final composites can act as highly active and stable ORR electrocatalysts. This project aims at developing original synthetic approach to the controllable synthesis of ultrathin Pt nanostructures/TMNs composites. The relationship among the size, loading amount of Pt nanostructures, structure, phase, crystallizing degree, and nitrogen content of TMNs as well as the electrocatalytic ORR performance is discussed in detail. Also, in situ measurement technology is used to unveil the structural change of the electrocatalyst to further understand the ORR mechanism. Through the combination of computational calculations and structural simulation, we discuss the synergic mechanism associated with ultrathin Pt nanostructures and TMNs, as well as the structure-activity relationship. This research will provide experimental and theoretical foundation for the fabrication of low-cost electrocatalytic materials with excellent performance.

贵金属Pt是氧还原反应中一种重要的电催化剂，解决其成本高、稳定性差等问题对实现能源的可持续发展具有重要的意义。将小尺寸的Pt生长在基底上可以有效地提高其原子利用率，但如何调控Pt的纳米结构以及Pt与基底的相互作用以进一步提升其活性和稳定性仍是目前存在的主要科学问题。本项目提出一种新型的原位附着-还原生长机制，将超细纳米Pt牢固地生长在过渡金属氮化物表面，作为高活性和高稳定性的复合氧还原电催化剂。本项目旨在发展新的合成方法实现对超细纳米Pt/过渡金属氮化物复合材料的原位可控合成；系统地研究Pt尺寸和负载量，氮化物的结构、晶相、晶化程度及含氮量对催化活性和稳定性的影响；利用电化学原位测试技术研究反应过程中催化剂的结构变化，深化对氧还原反应机理的认识，并结合理论计算和结构模拟揭示超细纳米Pt/过渡金属氮化物复合材料的协同催化机理和构效关系，为低成本、高性能的电催化剂的开发奠定理论与实验基础。

发展低成本、高效、稳定的电催化剂是能源、催化、环境等领域的研究热点，对我国碳中和战略规划的实现具有重要的意义。在本项目中，申请人发展了基于原位附着-还原生长机制的合成策略，制备出了贵金属Pt含量可调的双单原子Pt-Co电催化剂，获得了优异的电催化氧还原反应性能；也发展了界面调控策略制备出了NiFe基异质纳米材料，实现了尺寸、等级维度、电子结构的协同调控，获得了优异的电催化产氧和尿素氧化性能。采用电子显微技术、X射线衍射、X射线光电子能谱、同步辐射等技术深入研究其微观结构，系统地研究了催化剂的几何结构、电子结构等与实验参数间的依赖关系，并结合理论计算阐明电催化反应机制，深化对材料的构效关系的理解，为高效的电催化剂的设计合成提供理论依据。