Enabling the anodic electrooxidation of alcohols and N2 by optimization of active catalyst modified electrodes

• Applicant: Professorin Dr.-Ing. Corina Andronescu
• Subject Area: Technical Chemistry
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 413163866

Finding anodic oxidation reaction which can replace the oxygen evolution reaction (OER) is the main goal of TP9, focusing on N2 oxidation (N2Ox) and alcohol (glycerol - GOR and solketal - SOR) electrooxidation. To promote the conversion, not only the catalyst but also the electrode structure is important. The activation of the N2 molecule is highly challenging due to the high stability of the triple bond. In this project, we will explore the direct electrochemical oxidation of N2 to NOx compounds as a green alternative to the Ostwald process, using electrocatalyst materials developed in the consortia. While aiming to activate N2 in aqueous electrolytes, water splitting is often the dominant process, leading to a low conversion of N2 reflected by the low reported faradaic efficiencies for N2 electrooxidation. Therefore gas diffusion electrodes will be developed in the project to promote an increased mass transport of N2 while controlling the water access to the catalyst layer and thus suppress the competing oxygen evolution reaction (OER). Tuning of the electrode hydrophobicity using different ionomers or polymers will be explored to promote N2Ox over OER. A deeper understanding of the reaction mechanism will be performed for selected catalysts by DEMS studies and ATR-IR (cooperation with TP7) as well as theoretical calculations (cooperation with TP11). The research conducted in the previous funding period regarding glycerol electrooxidation will also be continued, using identified catalysts in the first funding period. Here the goal is to understand how the electrode structure can be used to enable high current density to be recorded. We will also explore the tunability in terms of hydrophobicity/ion-conductivity of the catalyst-deposited electrodes by adding PTFE or/and ionomers to elucidate their influence on the GOR. The effect of the electrolyte composition (e.g., pH) and the applied potential on the GOR will be investigated. DEMS will also be used herein to study the competition GOR-OER through a protocol already developed in the first funding period. This approach will enable the in-situ quantification of O2 and other possible GOR intermediates. The objective is to reach an optimal GOR activity and selectivity towards forming value-added products. Additionally, the activities related to solketal electrooxidation (SOR), which were started in the first funding period, will be continued as this reaction was yielding higher selectivity towards the formation of the high-valued product glycerate.

• DFG Programme: Research Units
• Subproject of: FOR 2982: UNODE - Unusual Anode Reactions
• Major Instrumentation: Ion chromatograph
• Instrumentation Group: 1350 Flüssigkeits-Chromatographen (außer Aminosäureanalysatoren 317), Ionenaustauscher