高载量杂原子稳定的铂单原子酸性氧还原催化剂的可控构筑及性能研究

How to remarkable decrease the usage of precious and scarce platinum-based catalysts is one of the main obstacles to realize large scale application of proton exchange membrane fuel cells (PEMFC). At this juncture, Pt single atom catalyst (SAC), which represents the lowest size limit to obtain the maximum atom efficiency and expose the most active sites, attracts much attentions. However, the high ORR activity through 4-electron pathway for Pt SAC is restricted. Additionally, simultaneously achieve both high density and stability of Pt single atom still remain a big challenge. Therefore, we plan to propose a step-by-step protection strategy to prepare a high-loading single-atomic heteroatom-anchored Pt catalyst. By elaborately regulating the type of heteroatoms (N, S, P, and B) as well as their doping styles, the surface state of Pt can be efficiently modified, thus, achieving a suitable Pt site for oxygen chemisorption and then boosting its intrinsic activity. Combination with advanced characterization techniques and theoretical calculations, further studies will demonstrate the ORR mechanisms, and disclose the coupling relationships between geometric/electronic structure and ORR performance, which will in turn benefit design and construction of high-loading Pt SAC, finally, leading a high ORR performance. These results may pave an avenue for efficient decrease the costs of PEMFC.

质子交换膜燃料电池商业化的关键挑战之一是如何降低阴极氧还原贵金属Pt催化剂的用量。Pt单原子催化剂可实现Pt最大化利用，但其关键科学问题与挑战在于如何实现高密度Pt单原子、如何稳定存在以及如何提升Pt单原子本身四电子氧还原活性。本项目拟基于前期实验基础，采用一种逐级保护的新策略，实现构筑高载量的杂原子锚定的高性能Pt单原子酸性氧还原催化剂。通过调控杂原子类型（N、S、P和B）和掺杂形式有效调控Pt单原子表面微观特性，从而调控其对反应物种的吸脱附行为，进而实现高活性四电子氧还原；结合先进表征技术和相关理论计算，阐明杂原子锚定的Pt单原子催化剂氧还原催化机制、构效关系与稳定机制，进而反馈指导催化剂的设计与合成，以期获得高密度、高稳定、高活性的杂原子-Pt单原子酸性氧还原催化剂，为降低质子交换膜燃料电池成本提供一种新的思路。

燃料电池阴阳两极低丰度/高价格贵金属铂的大量使用是限制燃料电池规模化应用的核心关键之一。对此，本项目围绕低成本、高性能燃料电池低铂/非铂氧还原阴极和氢氧化阳极催化剂这一关键科学问题，以氮稳定铂单原子（低铂）催化剂为研究主线，发展了高性能氧还原氮稳定铂单原子催化剂及其制备工艺，揭示了构效关系并探讨了相关催化反应机制；可控构筑了FeCo@NC核壳型非铂电催化剂并探究了氮碳壳层石墨化程度对催化剂电化学性能的影响规律；基于新开发的制备策略，开发了2种贵金属类非铂电催化剂（碳负载的小尺寸高分散PdAg合金颗粒、Ru纳米晶催化剂），并考察了PdAg合金纳米颗粒碳基催化剂在燃料电池阳极氢氧化反应中的电催化性能及构效关系。此项目的开展丰富了燃料电池低铂/非铂阴阳两极电催化材料体系，催化材料开发策略以及研究方法；研究结论有望为低成本、高性能催化剂开发提供强有力的指导和帮助。