Design of reversible iridium based electrocatalyst for oxygen evolution reaction and hydrogen evolution/oxidation reaction.

Abstract

In the past decades, great attention has been focused to increase activity of fuel cell and water electrolysis, which produce and save energy as hydrogen with clean and renewable property. Water electrolysis which converts energy into chemicals is a combination of hydrogen evolution reaction (HER) and Oxygen evolution reaction (OER). In the fuel cell, oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR) are occurred to produce electricity by consuming hydrogen and oxygen. To commercialize these systems, the electrode should have reversibility to opposite potential due to reverse current. When shut down is occurred, the polarity of HER and OER electrode is reversed due to reversed current in water electrolysis. In fuel cell operation, fuel starvation occurred at anode side leads reverse potential, causing rapid damage on anode electrode. [1-3] To prevent this degradation, OER catalytic activity of anode electrode in fuel cell is necessary to accelerate OER reaction as side reaction by decreasing carbon corrosion reaction, leading reduced damage of catalyst support. Thus, catalyst having reversible bifunctional HER/OER, HOR/OER catalyst should be developed for real application In this study, we report the design of reversible trifunctional iridium alloy electrocatalysts for OER, HER and HOR, having thin reversible oxide layer for HER/OER or HOR/OER by proving depth XPS, in situ/operando ICP and in situ/operando XANES results.