IrxNb1-XO2 Mixed Metal Oxides As Anode Catalyst for PEM Electrolysis: From Fundamentals to Application

Abstract

Summary. Here we describe the synthesis of IrxNb1-xO2 (mixed) metal oxides powders with several compositions. The catalysts are characterized with a variety of techniques to achieve a structure – activity relation. Furthermore, the effect of annealing temperature is addressed. Promising catalysts were tested in a full electrolysis cell as well. . Electrochemical water splitting will play a crucial role in future industries and will contribute to a more sustainable economy. Hydrogen produced by electrolysis is suitable to replace hydrogen produced by fossil fuels, enables the electrification of multiple sectors and can be used as long- and short-term chemical energy storage system [1].Here we describe the synthesis of IrxNb1-xO2 (mixed) metal oxides powders. Several compositions regarding the Ir/Nb ration are synthesized and studied. The study is based on previous experimental and theoretical findings using model films of IrxNb1-xO2 [2]. We address fundamental properties like crystal structure and composition and furthermore, test the catalysts in full electrolysis cell measurements. The synthesized materials are analysed using a variety of techniques, like XRF, XRD, RDE, BET, SEM, TEM, TGA and conductivity measurements to determine the activity and stability, crystal structure, morphology and conductivity. Furthermore, the effect of the annealing temperature on the above mentioned properties was studied. The optimal composition was determined based on activity and stability measurements in a three-electrode setup and physical properties like the powder conductivity.The synthesized catalysts could outperform commercial catalysts in terms of activity and stability and can be used with lower Ir loadings. XRD measurements reveals an IrO2 rutile structure with very broad peaks, indicating an amorphous crystal structure.The most promising catalysts were evaluated in a full electrolysis cell with different loadings.[1] Getting Hydrogen to the Gigaton Scale; B. S. Pivovar, M. F. Ruth, A. Nakano, H. Furutani, C. Hebling, T. Smolinka; Electrochem. Soc. Interface. 2021, 30, 85.[2] Molecular Analysis of the Unusual Stability of an IrNbOx Catalyst for the Electrochemical Water Oxidation to Molecular Oxygen (OER); C. Spöri, L. J. Falling, M. Kroschel, C. Brand, A. Bonakdarpour, S. Kuhl, D. Berger, M. Gliech, T. E. Jones, D. P. Wilkinson, P. Strasser