Accelerating Bubble Detachment in Porous Transport Layers with Patterned Through-Pores

Abstract

Mass transport losses ultimately suppress gas evolving electrochemical energy conversion technologies, such as fuel cells and carbon dioxide electrolyzers, from reaching the high current densities needed to realize commercial success. In this work, we reach ultrahigh current densities up to 9 A/cm 2 in a polymer electrolyte membrane (PEM) water electrolyzer with the application of custom porous transport layers (PTLs) with patterned through-pores (PTPs), and we reduce the mass transport overpotentials of the electrolyzer by up to 76.7 %. This dramatic performance improvement stems from the 43.5 % reduction in gas saturation at the catalyst layer-PTL interface region. Moreover, the presence of PTPs leads to more rapid bubble coalescence and subsequently more frequent bubble snap-off (∼3.3 Hz), thereby enhancing the rate of gas removal and liquid water reactant delivery to the reaction sites. This work is highly informative for designing PTLs for optimal gas removal for a wide range of gas evolving electrochemical energy conversion technologies.

Increasing the performance of an anion-exchange membrane electrolyzer operating in pure water with a nickel-based microporous layer

“…Connected channels are mainly responsible for the nonwetting flow and the rim of the pores is involved in the wetting-phase exchange. The big pores might accelerate the gas transport and less gas accumulates near the catalyst layer MPL interface, similar to the modification of commercial PTLs reported by Lee et al, 74 thus, the water transport also is improved. Another explanation for the improved performance is that the favored nucleation sites are outside of the NiMPL-PTL due to a diffusion flux without nucleation inside the small pores.…”

A high-performance, durable and low-cost proton exchange membrane electrolyser with stainless steel components

“…Similar observations are reported in the previous literature. 46,47 First, Lee et al revealed via modelling and in operando neutron imaging experiments that having a porosity gradient from low to high porosity facilitates mass transport during electrolysis. Moreover, they further 47 demonstrated that when a custom pore structure was applied to the PTL (i.e., pores with diameters excessively larger than the average pores in the PTL), the gas saturation at the catalyst layer-PTL interface was significantly reduced and mass transport behaviour was enhanced particularly at higher current density operation.…”

Constructing Supports–Network with N–TiO2 Nanofibres for Highly Efficient Hydrogen–Production of PEM Electrolyzer

“…The more hydrophilic surface of IrO 2 /N-TiO 2 indicates superior electrolyte penetration and gas adsorption-desorption. To verify the superior kinetics and mass transport of IrO 2 /N-TiO 2 , the voltage losses of kinetic losses, ohmic losses, and mass transport losses were estimated [19]. For an electrolysis cell, the cell voltage is the sum of thermodynamic voltage E 0 (p, T), ohmic losses (R j), kinetics losses, and mass transport losses (Equation ( 2)).…”