No 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 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 oxygen evolution. 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. Hydrogen in a future energy conversion systemHydrogen is believed to become a major energy carrier in the future, besides electrons, especially for transport purposes and for intermediate storage of renewable energy. Hydrogen may then be transformed to power by electrochemical energy conversion in fuel cells producing DC-power, or by internal combustion. Water electrolysis is the most feasible method for hydrogen production from renewable energy sources like wind-and sun-power. Increased energy and volume efficiencies of water electrolysis systems are of great importance. PEM water electrolysis uses technology similar to PEM fuel cells. The Oxygen anode is the main potential controlling part. Noble metal oxides show high activity for oxygen evolution in PEM water electrolysis systems with the following electrode processes. Cathode: 4H + + 4e -→ 2H 2 Anode: 2H 2 O → O 2 + 4H + + 4e -Total: 2H 2 O → O 2 + 2H 2

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.