Advances in Oxygen Evolution Electrocatalysts for Proton Exchange Membrane Water Electrolyzers

Abstract

Figure 2. Schematic acidic OER mechanisms, in which both single-and dual-site pathways are presented. a) The adsorbate evolution mechanism (AEM). b) The lattice oxygen evolution mechanism (LOM).

Iridium nanohollows with porous walls for acidic water splitting

“…[1][2][3][4][5] In particular, proton exchange membrane water electrolyzers (PEMWEs), featuring high voltage efficiency, high current densities, rapid response and low gas crossover, are of wide research interest. [6][7][8][9][10] A crucial challenge related to PEMWEs arises from the sluggish kinetics of the anodic oxygen evolution reaction (OER)a complex reaction that requires the transfer of four electrons and protons. Iridium is the only element that catalyzes the OER in strong acid with satisfactory activity and stability.…”

Mesoporous Mn–Fe oxyhydroxides for oxygen evolution

“…The oxygen evolution reaction (OER), which is essentially sluggish, plays a crucial role in renewable energy technologies including reversible fuel cells, rechargeable metal/air batteries, and water splitting. 1–6 Ru/Ir-Based materials are the most active OER catalysts in acidic media, but the fancy price and rareness impede their large-scale commercial application. 7,8 So far, a great deal of effort has been made in the fabrication of cost-efficient alternatives, such as transition metal sulfides, 9 selenides, 10 phosphides, 11 borides, 12 carbides, 13 nitrides, 14 oxides/hydroxides/oxyhydroxides, 15 and single-atom catalysts.…”

Self-Supported Bimetallic Phosphide Heterojunction-Integrated Electrode Promoting High-Performance Alkaline Anion-Exchange Membrane Water Electrolysis

“…However, noble-metal-based catalysts must be used due to the corrosive environment of the acid. Also, the stack materials used for the configuration of the PEM system are more expensive than those of other devices. , For the most mature AWE technology in the industry, although non-noble-metal catalysts can be used, there are still many challenging issues difficult to overcome . The performance of the cell system (200–400 mA cm –2 at 1.8–2.4 V) remains far from satisfactory because of the high ohmic impedance, mainly from the diaphragm .…”