Engineering Iridium-Based Oxygen Evolution Reaction Electrocatalysts for Proton Exchange Membrane Water Electrolyzers

Abstract

The electrocatalytic water splitting technology, especially proton exchange membrane water electrolyzers (PEMWEs), is one of the core hydrogen production technologies to achieve carbon-free energy cycling. However, high acid corrosion and anodic potential operating conditions pose serious challenges for the development of PEMWEs. It is urgent to explore highly active, durable, and compatible anodic catalysts for the complex oxygen evolution reaction (OER). Hitherto, iridium (Ir)-based electrocatalysts (IBCs) with trade-off catalytic activity and stability are the primary candidates for the OER. Yet, the continued huge consumption of expensive and scarce Ir species severely hinders the widespread deployment of PEMWEs. It is necessary to systematically understand the latest research progress in IBCs to guide the controllable construction of catalysts with low-Ir loading to meet industrial demands. In this review, the conventional OER catalytic mechanism and Ir species-related failure modes are introduced. Subsequently, four common classes of IBCs, including Irbased metals, oxides, perovskites, and pyrochlores, as well as attempts to correlate structural features of catalysts with their performance are reviewed. Within this scenario, the actual performances of bright representative IBCs applied in practical PEMWEs are also discussed. At the end of this review, unresolved issues and challenges in the field are proposed with a view to formulating effective strategies to break the bottleneck of commercial deployment of PEMWEs.

Thermal‐Driven Orderly Assembly of Ir‐atomic Chains on α‐MnO2 with Enhanced Performance for Acidic Oxygen Evolution

“…It proves that an Ir-rich structure is formed on the surface of α-MnO 2 through the ion exchange reaction, which makes it easy to expose more active sites so that the utilization rate of Ir atoms is higher than that of the conventionally hydrothermally prepared IrMnO x solid solution. [23] The results are similar to the rule of the EDX energy spectrum of IrMnO@Ir NRs (Figure S4).…”

Designing active and stable Ir-based catalysts for the acidic oxygen evolution reaction

“…However, carbon will undergo serious corrosion under the operating voltage of the OER, which makes it unsuitable as a support for Ir-based catalysts. 62 According to the pH–potential diagrams, some oxides with strong binding energy, such as SnO 2 etc. , can be stable electrocatalyst supports with strong anti-corrosion resistance under the conditions of strong acid and high voltage.…”

Recent advances and perspectives of Ir-based anode catalysts in PEM water electrolysis

“…7,8 Hydrogen can be generated by water electrolysis technology driven by renewable energy built using a clean energy system to realize a green hydrogen cycle. 9,10 At present, there are mainly two types of water electrolysis technology used in industry: alkaline water electrolysis (AWE) and proton exchange membrane water electrolysis (PEMWE). 11 However, AWE requires a long start-up preparation and presents a slow response, which makes it difficult to adapt to frequent changes in electricity generated by renewable energy (such as solar energy and wind energy).…”