Exploring zero-gap Water Electrolysis Technologies: Benchmarking, Evaluation, and Comparative Analysis

Abstract

Water electrolysis is a promising process to produce green hydrogen, a sustainable and environmentally friendly fuel and a crucial chemical used in numerous industrial applications. Zero-gap water electrolysers have become a key technology for green hydrogen production, mainly due to their high efficiency and hydrogen purity and their rapid response to a wide range of operating conditions and intermittent electricity, facilitating their coupling with renewable energy sources. In Chapter 1, the fundamentals and history of the water electrolysis process are discussed, and the low-temperature water electrolyser technologies are introduced. Moreover, the key evaluation parameters of water electrolysis electrocatalysts are reported. In Chapter 2, all the experimental techniques used throughout this work are introduced and discussed, covering their theoretical background and operation principles.

In Chapter 3, a standard anion exchange membrane water electrolyser, a type of zero-gap electrolyser design, is developed and optimised to be used as a universal testbed for evaluating novel electrocatalysts and other components of (anion exchange membrane) water electrolysis. The benchmark is developed because of the absence of a reliable evaluating protocol due to variations in testing conditions and water electrolyser components across studies, obstructing a comprehensive and cohesive comparison of new electrocatalysts (or other components of anion exchange membrane water electrolysis technology). The construction and operation of the standard water electrolyser are described in detail. In addition, 3D drawings of the water electrolyser components are provided (located in the University of Glasgow’s open access data repository, https://researchdata.gla.ac.uk/1672/), enabling others to construct and operate their own identical flow cell.

In Chapter 4, the flow cell introduced in Chapter 3 is used to evaluate a new commercially available polymer membrane as an alternative proton exchange membrane to Nafion and Aquivion membranes, which have been in short supply recently. The performance, stability, and hydrogen crossover characteristics of the new membrane is evaluated and compared to those of the Nafion and Aquivion membranes.

In Chapter 5, the standard water electrolyser developed and optimised in Chapter 3 is adopted to evaluate a radiation-grafted anion exchange membrane supplied by a research team based at the University of Surrey. The membrane is assessed and compared to a commercial anion exchange membrane (FAA-3-50).