Optimization of electrocatalysts for fuel cell applications without alloying: a joint theoretical and experimental study

多相催化，包括电催化，是决定当今生活标准的支柱之一，因为催化剂是现代工业中的关键材料之一。因此，从根本上理解控制众多催化性能的机理是非常重要的。当今催化领域最大的挑战之一是开发能够加速燃料电池中关键反应的活性和稳定的材料，主要关注发生在这些设备的阴极侧的氧还原反应(ORR)。据估计，将聚合物电解质膜燃料电池(PEMFC)中现有的铂电催化剂的ORR活性提高~4-5倍，将使这种昂贵材料的每辆车所需的量减少到目前普通内燃机汽车催化转化器中平均使用的量(即从目前的~20g降至~4-5g)。最近报道了无数种催化剂来应对这一挑战。这些努力的主要重点之一是用过渡金属精制铂合金。事实上，与纯铂相比，铂的活性可以提高多达10倍(铂-镍系统)。然而，到目前为止，某些稳定性问题在很大程度上限制了它们的使用。该项目利用最新的实验发现和对如何在不进行任何合金化的情况下将纯铂的表面活性提高至少3.5-4.5倍的基本认识，设计出用于氧还原反应的活性和更稳定的电催化剂。这种方法的关键事实是，有可能通过控制ORR活性中心附近的原子配位来增加例如铂的活性。本项目的目的是阐明和实现具有最大密度的活性中心的三维准开放结构，该结构具有正确的配位、改善的稳定性和局部质量传输特性。该项目的成功实现不仅将清楚地向研究人员和工程师展示如何在没有合金化的情况下改进现有材料；它可能会建立一种全新的方法，基于不同水平的理论计算和实验方法的结合，开发适用于现实世界电催化的开放式三维纳米结构材料。

Heterogeneous catalysis, including electrocatalysis is among the pillars determining the standards of life nowadays, as catalysts are among the key materials in the modern industry. Fundamental understanding of the mechanisms controlling numerous catalytic properties is therefore of significant importance. One of the most substantial challenges in catalysis today is to develop active and stable materials capable of accelerating key reactions in fuel cells, with a prime focus being set on the oxygen reduction reaction (ORR) taking place at the cathode side of these devices. It has been estimated that increasing the ORR-activity of current Pt electrocatalysts in polymer electrolyte membrane fuel cells (PEMFCs) by ~4-5 times would reduce the necessary amount of this expensive material per vehicle to that averagely used in the catalytic convertors of normal combustion engine cars nowadays (i.e. only to ~4-5g from the current ~20g). Myriads of catalysts were reported recently to address this challenge. One of the main focuses in these efforts was elaboration of alloys of platinum with transition metals. Indeed the activity of Pt can be improved by up to 10 times (Pt-Ni system) compared to pure Pt. However, certain stability issues so far largely limit the use of them. This project uses recent experimental discoveries and fundamental understanding of how one can increase the activity of the surface of pure Pt by at least the factor of 3.5-4.5 without any alloying to design active and more stable electrocatalysts for the oxygen reduction reaction. The key fact in this approach is that it is possible to increase the activity of e.g. Pt by controlling the atom coordination near to the ORR active sites. The aim of this project is to elucidate and implement 3D quasi-open structures with the maximum density of active sites of right coordination, improved stability and local mass transport properties. Successful realization of the proposed project would not only clearly demonstrate the researchers and engineers how to improve the existing materials even without alloying; it would likely establish an entirely new methodology for the development of heterogeneous electrocatalysts based on a combination of theoretical calculations of different levels and experimental approaches which elaborate open 3D-nanostructured materials applicable in the real-world electrocatalysis.