Key Takeaways & Executive Findings
- •• A novel triple-layer Ti-porous transport layer (PTL), fabricated using a practical and scalable tape casting and roll calendering process, enhances catalyst utilization by increasing interfacial contact area and the triple-phase boundary. • The ultra-high porosity (75%) backing layer and graded structure maximize oxygen transport, mitigate oxygen accumulation, and improve reactant accessibility. • Electrochemical evaluations demonstrate a 127 mV reduction in voltage at 2 A cm−2 compared to a commercial PTL, accelerating proton exchange membrane water electrolysis commercialization and supporting the transition to sustainable energy. • Digital twin technology using X-ray revealed increased contact area and triple-phase boundary at the interface with the catalyst layer, significantly improving oxygen evolution reaction kinetics.
Abstract
The commercialization of proton exchange membrane water electrolysis (PEMWE) for green hydrogen production hinges on the development of low-cost, high-performance titanium porous transport layers (PTLs). This study introduces a triple-layer Ti-PTL with a graded porous structure and a 75% ultra-high porosity backing layer, fabricated through tape casting and roll calendering. This triple-layer PTL, composed of a microporous layer, an interlayer, and a highly porous backing layer, enhances catalyst utilization, mechanical integrity, and mass transport. Digital twin technology using X-ray revealed increased contact area and triple-phase boundary at the interface with the catalyst layer, significantly improving oxygen evolution reaction kinetics. Numerical simulations demonstrated that the strategically designed porous structure of the triple-layer PTL facilitates efficient oxygen transport, mitigates oxygen accumulation, and improves reactant accessibility. Electrochemical evaluations showed improved performance, achieving 127 mV reduction in voltage at 2 A cm−2 compared to a commercial PTL, highlighting its potential to enhance PEMWE efficiency and cost-effectiveness.
1. Introduction
The increasing global demand for energy has intensified the urgency to develop eco-friendly energy solutions to combat climate change [1–3]. Transitioning from fossil fuel-based systems to sustainable energy sources is critical in achieving a carbon–neutral future. Among these sources, hydrogen energy has gained significant attention for its potential as a clean energy and sustainable alternative [4–6]. In particular, green hydrogen, produced via water electrolysis powered by renewable energy sources such as solar and wind, has emerged as a key pillar of this transition. Distinguished by its zero greenhouse gas emissions, green hydrogen offers an environmentally friendly pathway compared to traditional hydrogen production methods reliant on fossil fuels.
Proton exchange membrane water electrolysis (PEMWE) is one of the most promising technologies for producing green hydrogen. This technology utilizes a polymer electrolyte membrane to split water into hydrogen and oxygen, offering benefits such as high current density, rapid system response, and low operating temperatures [7–9]. These attributes position PEMWE as a mature and reliable hydrogen production technology.
Despite these advantages, challenges remain in achieving the widespread commercialization of PEMWE systems, with high stack cost being a primary obstacle [10, 11]. The stack comprises costly components, including the catalyst-coated membrane (CCM), bipolar plate (BPP), and porous transport layer (PTL), significantly contributing to the overall system cost [12, 13]. Addressing this issue requires innovative approaches, such as reducing material usage, developing cost-effective manufacturing processes, or improving system performance. Enhancing cell performance, in particular, can increase hydrogen production efficiency, ultimately lowering the cost per unit of hydrogen [14, 15]. Among these components, the PTL accounts for a substantial share of the PEMWE stack cost due to the requirement for corrosion-resistant Ti materials at the anode [16–18]. In particular, the manufacturing process of Ti materials with complex pore structures that facilitate efficient oxygen and water transport contributes substantially to the overall PTL cost. Furthermore, the microstructural characteristics of the PTL play a critical role in the performance of PEMWE cells. Its surface structure influences catalyst utilization at the anode catalyst layer interface, while pore structure attributes such as pore size and porosity affect mass transport efficiency [19, 20].
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Seong Hyun Park, Young Je Park, Seungsoo Jang, Pilyoung Lee, Soobin Yoon, Young-June Park, Chi-Young Jung, Kang Taek Lee (2025). Triple-Layer Porous Transport Layers with Ultra-High Porosity for Enhanced Oxygen Transport and Catalyst Utilization in Water Electrolysis. Nano-Micro Letters. https://doi.org/10.1007/s40820-025-01831-z
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Frequently Asked Questions
What is the main innovation of this study?
The study introduces a triple-layer Ti-porous transport layer (PTL) with a graded porous structure and ultra-high porosity (75%) backing layer, fabricated via tape casting and roll calendering, which enhances catalyst utilization and oxygen transport in water electrolysis.
How does the triple-layer PTL improve performance?
The triple-layer PTL increases the interfacial contact area and triple-phase boundary with the catalyst layer, improves oxygen transport and mitigates oxygen accumulation, leading to a 127 mV reduction in voltage at 2 A cm−2 compared to a commercial PTL.
What methods were used to evaluate the PTL?
The study used digital twin technology with X-ray imaging to analyze contact area and triple-phase boundary, numerical simulations to assess oxygen transport, and electrochemical evaluations to measure performance.
What is the significance of the ultra-high porosity backing layer?
The 75% porosity backing layer maximizes oxygen transport, reduces oxygen accumulation, and improves reactant accessibility, which are critical for efficient water electrolysis.
How does this research contribute to green hydrogen production?
By enhancing PEMWE efficiency and cost-effectiveness, this research supports the commercialization of green hydrogen production, aiding the transition to sustainable energy.
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