Optical High-Throughput Screening for Activity and Electrochemical Stability of Oxygen Reducing Electrode Catalysts for Fuel Cell Applications

A fluorescence-based electro-optical high-throughput method and setup for testing the oxygen reduction reaction (ORR) activity and electrochemical stability of 60 materials in parallel is described. We present thus a quantitative method for activity measurements for ORR-catalysts by optical fluorescence data acquisition. The fluorescence behavior of fluorescein, phloxine B, and umbelliferone as indicators is presented. The effect of oxygen concentration, saturation, and supply on electrochemical response is presented. Corrections for internal resistance differences and intensity differences are described. The final method allowed position independent determination of activities on the working-electrode library, containing up to 60 different electrocatalysts. A total of 378 selected mixed oxides have been studied. Cu/Ni/Mn and Co/Ni/Mn oxides proved electrochemically most active and comparable to a Pt-containing reference catalyst

Search for New Catalysts for the Oxidation of SO₂

The focus of this paper is the search and characterization of novel catalysts for the gas phase oxidation of concentrated SO₂ for the production of sulfuric acid. Modern high-throughout (HT) methods such as emissivity corrected Infrared Thermography (ecIRT) and automated synthesis techniques were used for the synthesis and activity measurements of the samples. In addition a plug flow reactor that uses UV–vis online analytics for the quantification of the SO₂ conversion was designed, built and used for validation of the HT results. The study started with a highly diverse search space of elemental compositions designed for potential discovery. About a thousand samples were synthesized using sol–gel recipes and screened for catalytic SO₂ oxidation activity over a temperature range of 330–450 °C. Several novel catalyst systems were discovered during the screening process and the most interesting systems were further characterized. The most important doping effects on activity found were the influence of bismuth and selenium doping on standard sulfuric acid catalysts, the activity gain of chromium based catalysts caused by the doping with antimony and the activity gain of chromium as well as iron and vanadium based catalysts caused by the doping with tin