Development of high-performance catalyst-coated membranes for pressure-differential proton exchange membrane water electrolysers

Hou, Dehua (2025). Development of high-performance catalyst-coated membranes for pressure-differential proton exchange membrane water electrolysers. University of Birmingham. Ph.D.

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Abstract

The proton exchange membrane water electrolysis (PEMWE) has emerged as a key technology in sustainable hydrogen production, offering high efficiency and integration potential with renewable energy systems. The catalyst-coated membrane (CCM) serves as the core component of PEMWEs, and the development of high-power performance CCMs is critical for enabling large-scale commercial deployment of this technology. This PhD research systematically investigates the optimisation of testing protocols, CCM fabrication processes, and hydrogen crossover mitigation strategies to address the challenges associated with proton exchange membrane water electrolysers under differential pressure conditions.
Initially, the research focuses on establishing a standard testing protocol to ensure consistent and reliable evaluation of CCMs. This involves investigating the influence of the geometric area and assembly force during the assembly of the testing cell, as well as optimising key operational parameters, including water flow rates, clamping forces and conditioning procedures. Following the optimisation of the testing protocol, materials used for the PEMWE single cell are explored, including membranes, porous transport layers, catalysts, and ionomers. After material selection, CCM fabrication processes are further studied, from the catalyst ink formulation and processing to spray-coating techniques and hot pressing procedures. This optimisation significantly improves CCM performance. The optimised CCMs surpass the DOE’s 2022 targets, making progress toward the ambitious goals set for 2026.
Building upon this foundation, a key innovation of this work is the introduction of a platinum functional layer at the anode/membrane interface, deposited via sputter coating, to mitigate hydrogen crossover. Experimental results demonstrate a 73% reduction in hydrogen crossover at atmospheric pressure and a 66% reduction at 10 bar differential pressure, highlighting the layer’s effectiveness across varying operating pressures. To further understand hydrogen permeation mechanisms, a diffusion-based qualitative analysis model is developed to provide theoretical insights into the influence of functional layer placement and gas transport properties. Furthermore, accelerated stress tests are designed to simulate dynamic load conditions to evaluate the durability of the functional layer for PEMWEs under differential pressures. The tests confirm the robustness of the functional layer, which retains 94% of its hydrogen crossover mitigation capability at 0.25 A/cm2 and 99% at 2.50 A/cm2 after the equivalent of 100 hours of operation.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):