Materials for Electrocatalysis of Oxygen Evolution in PEM Water Electrolysis

Abstract

Proton exchange membrane (PEM) water electrolysis offers several advantages compared to the traditional alkaline technologies including higher energy efficiencies, considerably higher specific production rates leading to more compact design, and avoiding a liquid and highly corrosive electrolyte. The oxygen electrode is the critical part in the energy consumption of such cells. To obtain high performance, electrocatalytically very active anode materials have to be developed for the oxygen evolving interface. The most promising electrocatalytic materials are based on IrO 2 and RuO 2 , preferably in mixtures with other transition metal oxides with electronic conductivity. Excellent performance has been obtained by using nanocrystalline electrocatalysts based on iridium oxide with additions of ruthenium oxide and/or tin oxide, forming rutile structures, or mixed with tantalum pentoxide.This concept has been applied extensively in our work and has been successful in understanding oxygen evolution performance variations in IrO 2 -RuO 2 , IrO 2 -SnO 2, IrO 2 -RuO 2 -SnO 2 and IrO 2 -RuO 2 -Ta 2 O 5 systems.

Probing Surface Oxide Formation and Dissolution on/of Ir Single Crystals via X-ray Photoelectron Spectroscopy and Inductively Coupled Plasma Mass Spectrometry

“…Micrometer-sized IrO x particles (with x ≤ 2) are currently the state-of-the-art electrocatalyst for the OER in acidic conditions. [15][16][17][18] x can be (i) produced by thermally annealing Ir particles in an oxidizing atmosphere, leading to highly crystalline oxides in the (+IV) oxidation state, or (ii) generated operando in the PEMWE during the materials' conditioning stage. However, depending on their preparation method, the IrO x particles feature different initial and long-term OER activity: it is thus extremely important to gain insights into the early stages of oxidation on well-defined surfaces, such as Ir(hkl) single crystals.…”