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

氧还原反应（ORR）由于其各种应用而成为最重要的电催化反应之一，特别是在聚合物电解质膜（PEM）燃料电池中，而且在氧传感器中，或者潜在地在金属空气电池中。到目前为止，用于ORR的最好和最常用的催化剂是Pt基材料，主要是碳负载的Pt或Pt合金纳米颗粒催化剂。这些材料的高价格是PEM燃料电池的经济竞争力引入的主要障碍之一。在本项目中，我们希望开发新的，Pt-贫或无Pt的氧化物和碳氧化物/氮化物/碳氧化物的ORR的早期过渡金属催化剂，优化的活性，选择性H2O形成和腐蚀稳定性在燃料电池相关的反应条件下。这将以非常系统的方法进行，一方面通过精心定制催化剂和/或其载体的纳米结构、孔隙率和化学组成，另一方面与其电催化性能相关。该目的将通过结合i）制备具有可变结构和组成的中孔、高表面积氧化物材料的合成方法，用碳和氮掺杂材料的非常受控的方法，使用具有稳定的高度多孔碳骨架的复合材料，其最近由申请人之一开发（Salzburg组），和ii）使用广泛的复杂的电化学、显微镜和（原位）光谱学方法学方法来以高度迭代的方式研究在另一申请人（乌尔姆组）的实验室中开发的高达燃料电池相关反应条件下的电催化反应。结合起来，这些测量将提供关于材料性质和催化性能之间的相关性的详细信息以及机理信息，从而为催化剂材料的进一步目标导向改进提供基础。

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.