Polymer electrolyte membrane electrolysis

Proton exchange membrane fuel cell

Electrode

Organic chemistry

Nafion

Hydrogen

Photocatalysis

Anode

Engineering

Catalysis

Electrolysis

Physical chemistry

Hydrogen production

Chemistry

Materials science

Membrane electrode assembly

Cathode

Iridium

Electrolyte

Water splitting

Chemical engineering

Electrolysis of water

Platinum

Electrochemistry

Biochemistry

Journal of The Electrochemical Society

In this study, the influence of catalyst loading on the performance of a proton exchange membrane (PEM) water electrolyzer is investigated (Nafion 212 membrane; IrO2/TiO2 (anode) and Pt/C (cathode)). Due to the fast kinetics of the hydrogen evolution reaction (HER) on platinum (Pt), the Pt loading on the cathode can be reduced from 0.30 mgPt cm−2 to 0.025 mgPt cm−2 without any negative effect on performance. On the anode, the iridium (Ir) loading was varied between 0.20–5.41 mgIr cm−2 and an optimum in performance at operational current densities (≥1 A cm−2) was found for 1–2 mgIr cm−2. At higher Ir loadings, the performance decreases at high current densities due to insufficient water transport through the catalyst layer whereas at Ir loadings <0.5 mgIr cm−2 the catalyst layer becomes inhomogeneous, which leads to a lower electrochemically active area and catalyst utilization, resulting in a significant decrease of performance. To investigate the potential for a large-scale application of PEM water electrolysis, the Ir-specific power density (gIr kW−1) for membrane electrode assemblies (MEAs) with different catalyst loadings is analyzed as a function of voltage efficiency, and the consequences regarding catalyst material requirements are discussed.

Analysis of Voltage Losses in PEM Water Electrolyzers with Low Platinum Group Metal Loadings