Abstract
Interfacial and bulk properties between the catalyst layer and the porous transport layer (PTL) restrict the iridium loading reduction for proton exchange membrane water electrolyzers (PEMWEs), by limiting their mass and charge transport. Using titanium fiber PTLs of varying thickness and porosity, the bulk and interface transport properties are investigated, correlating them to PEMWEs cell performance at ultra‐low Ir loadings of ≈0.05 mgIr cm−2. Electrochemical experiments, tomography, and modeling are combined to study the bulk and interfacial impacts of PTLs on PEMWE performance. It is found that the PEMWE performance is largely dependent on the PTL properties at ultra‐low Ir loadings; bulk structural properties are critical to determine the mass transport and Ohmic resistance of PEMWEs while the surface properties of PTLs are critical to govern the catalyst layer utilization and electrode kinetics. The PTL‐induced variation in kinetic and mass transport overpotential are on the order of ≈40 and 60 mV (at 80 A mgIr −1), respectively, while a nonnegligible 35 mV (at 3 A cm−2) difference in Ohmic overpotential. Thus at least 150 mV improvement in PEMWE performance can be achieved through PTL structural optimization without membrane thickness reduction or advent of new electrocatalysts.
Highlights
Proton exchange membrane water electrolyzers (PEMWEs) are increasingly being considered as an essential technology to integrate the growing share of renewable porosity, the bulk and interface transport properties are investigated, power into many energy sectors, since they correlating them to PEMWEs cell performance at ultra-low Ir loadings of convert renewable electricity into hydrogen,≈0.05 mgIr cm−2
The porous transport layer (PTL)-induced variation in kinetic and mass transport overpotential are on the order of ≈40 and 60 mV, respectively, while a nonnegligible 35 mV difference in exchange membrane, due to PEMWE’s superiority in coupling with renewable, intermittent sources of cheap electrons:[3,4] high current density operation resulting in small footprints, high turn-down ratios, Ohmic overpotential
We further explore the complex transport in these PTLs using a lattice Boltzmann method (LBM) in conjunction with the PTL tomography, of the oxygen distribution within PTLs at three different regions of catalyst layer/PTL (CL/PTL) interface, middle region of PTL, and PTL/flow field channel (PTL/channel) interface at a fixed current density of 3 A cm−2
Summary
Proton exchange membrane water electrolyzers (PEMWEs) are increasingly being considered as an essential technology to integrate the growing share of renewable porosity, the bulk and interface transport properties are investigated, power into many energy sectors, since they correlating them to PEMWEs cell performance at ultra-low Ir loadings of convert renewable electricity into hydrogen,≈0.05 mgIr cm−2. Proton exchange membrane water electrolyzers (PEMWEs) are increasingly being considered as an essential technology to integrate the growing share of renewable porosity, the bulk and interface transport properties are investigated, power into many energy sectors, since they correlating them to PEMWEs cell performance at ultra-low Ir loadings of convert renewable electricity into hydrogen,. It is found that the PEMWE performance is largely dependent on the PTL properties at ultra-low Ir loadings; bulk structural properties are which is a stable, clean energy carrier, and commodity chemical that can effectively displace fossil fuels in food production and manufacturing.[1,2] PEMWEs offer many advantages over other electrolysis critical to determine the mass transport and Ohmic resistance of PEMWEs chemistries, namely, KOH and anion while the surface properties of PTLs are critical to govern the catalyst layer utilization and electrode kinetics. At least 150 mV improvement in PEMWE pressurized hydrogen delivery without the performance can be achieved through PTL structural optimization without membrane thickness reduction or advent of new electrocatalysts
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