ERA-Chemistry: Novel Pt-poor catalysts for the electrocatalytic O2 reduction based on modified, nanostructured metal oxides

氧还原反应(ORR)是最重要的电催化反应之一，其应用非常广泛，特别是在聚合物电解质膜(PEM)燃料电池中，也在氧传感器或潜在的金属空气电池中。到目前为止，最好和最常用的ORR催化剂是铂基材料，主要是碳负载的铂或铂合金纳米颗粒催化剂。这些材料的高价是PEM燃料电池在经济上具有竞争力的主要障碍之一。在本项目中，我们希望开发用于ORR的新型贫铂或无铂氧化物和碳氧化合物/氮化物/碳氮化物早期过渡金属催化剂，在燃料电池相关反应条件下对活性、生成H2O的选择性和腐蚀稳定性进行优化。这将以一种非常系统的方法进行，通过刻意调整催化剂和/或其载体的纳米结构、孔隙率和化学成分，另一方面与其电催化性能相关联。通过结合i)制备结构和组成可变的介孔、高比表面积氧化物材料的合成方法、在材料中掺入碳和氮的非常受控的方法、使用由申请者之一(Salzburg组)最近开发的具有稳定的高度多孔性碳主干的复合材料以及ii)以高度迭代的方式使用范围广泛的复杂的电化学、显微和(原位)光谱方法来研究燃料电池相关反应条件下的电催化反应。这些测量结果将提供有关材料性能与催化性能之间关系的详细信息以及机理信息，从而为进一步针对性地改进催化剂材料提供依据。

The oxygen reduction reaction (ORR) is one of the most important electrocatalytic reactions due to its various applications, in particular in polymer electrolyte membrane (PEM) fuel cells, but also in oxygen sensors or, potentially, in metal air batteries. Until now, the best and most frequently used catalysts for the ORR are Pt-based materials, mainly carbon supported Pt or Pt-alloy nanoparticle catalysts. The high price for these materials is one of the main obstacles for the economically competitive introduction of PEM fuel cells. In the present project, we want to develop novel, Pt-poor or Pt-free oxide and oxycarbide/- nitride/oxycarbonitride early transition metal catalysts for the ORR, optimized with respect to activity, selectivity for H2O formation and corrosion stability under fuel cell relevant reaction conditions. This will be performed in a very systematic approach, via a deliberate tailoring of nanostructure, porosity and chemical composition of the catalyst and/or its support on the one hand correlated with its electrocatalytic performance on the other. This objective shall be reached by combining i) a synthetic approach to prepare mesoporous, high-surface area oxide materials of variable structure and composition, a very controlled approach of doping the material with carbon and nitrogen, the use of composite materials with a stable highly porous carbon backbone, which was recently developed by one of the applicants (Salzburg group), and ii) the use of a wide range of sophisticated electrochemical, microscopic and (in situ) spectroscopy methodic approaches to study electrocatalytic reactions under up to fuel cell relevant reaction conditions developed in the laboratory of the other applicant (Ulm group) in a highly iterative way. In combination, these measurements will provide detailed information on the correlation between materials properties and catalytic performance as well as mechanistic information, and thus provide a basis for further target-oriented improvement of the catalyst materials.