Physico-Chemical nanomaterials science

Supported Ir nanoparticles as catalyst for water electrolyzers: from synthesis to real application.
Blanco Redondo L., Lobko Y., Matolínová I., Matolín V.
Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science. V Holesovickach 2, 180 00, Prague 8, Czech Republic
E-mail: lublare93@gmail.com

In water electrolyzer systems, the positive electrode is one of the most important components, where the oxygen evolution reaction (OER) occurs. In this process, the water molecules are split into oxygen ions, protons, and electrons, and the oxygen gas is produced on the anode surface [1]. The state-of-the-art materials that catalyze OER are nanostructured ruthenium, iridium, and their oxides, but their cost and scarcity require reduction and enhancement of their utilization [2]. One morphological approach consists of the dispersion of the active material in a support in order to increase their mass activity. However, due to the high potential reached during operating conditions for water splitting, support materials have to possess a high corrosion resistance. Titanium oxides are good candidates because of their high thermal and chemical stability, low cost, and commercial availability [3]. But their poor electrical conductivity (∼10−6 S cm−1) makes the design of an active and stable catalyst a non-trivial task. 
In this work, Ir nanoparticles have been reduced on the surface of TiO2 nanoparticles, and a complete analysis of their morphological, chemical, and electrochemical properties has been carried out, including testing in-situ in a single cell water electrolyzer. The results show a successful performance of the supported Ir nanoparticles comparable to the pure Ir black nanoparticles but with an active metal loading five times lower. In addition, insights about the metal-support interaction have been studied to have a better knowledge about the catalyst properties.

1.	Sadhasivam T., Ho-Young J. Chapter 3 - Nanostructured bifunctional electrocatalyst support materials for unitized regenerative fuel cells // Nanostructured, Functional, and Flexible Materials for Energy Conversion and Storage Systems- 2020.- P. 69-103.
2.	Antolini E. Iridium as Catalyst and Cocatalyst for Oxygen Evolution / Reduction in Acidic Polymer Electrolyte Membrane Electrolyzers and Fuel Cells // ACS Catal. - 2014.- 4, N 5.- P. 1426-1440.
3.	Van Pham C., Bühler M. IrO2 coated TiO2 core-shell microparticles advance performance of low loading proton exchange membrane water electrolyzers // Applied Catalysis B: Environmental-2020.- P 269.- P. 118762.