Hydrogen is an important part of any discussion on sustainability and reduction in emissions across major energy sectors. In addition to being a feedstock and process gas for many industrial processes, hydrogen is emerging as a fuel alternative for transportation applications. Renewable sources of hydrogen are therefore required to increase in capacity. Low-temperature electrolysis of water is currently the most mature method for carbon-free hydrogen generation and is reaching relevant scales to impact the energy landscape. However, costs still need to be reduced to be economical with traditional hydrogen sources. Operating cost reductions are enabled by the recent availability of low-cost sources of renewable energy, and the potential exists for a large reduction in capital cost withmaterial and manufacturing optimization. This article focuses on the current status and development needs by component for the low-temperature electrolysis options.

Electrocatalysts are nanomaterials of paramount importance within water electrolyzers, because they facilitate the electron transfer between reactants and electrode, enabling the chemical transformation of water into hydrogen and oxygen. In this Perspective, recent findings in electrocatalyst development for the next generation of polymer electrolyte membrane (PEM) water electrolyzers at scale are discussed. We discuss opportunities to create catalyst architectures, the importance to demonstrate electrode manufacturing tools, and how useful advanced characterization methods shall, in the short term, allow large-scale deployment of water splitting devices with higher efficiency, acceptable durability, and low cost. We envision next-generation PEM cells permitting a transformational change in the chemical industry by the manufacturing of low-cost hydrogen.

Proton exchange membrane water electrolyzers (PEMWEs) have demonstrated enormous potential as the next generation hydrogen production technology. The main challenges that the state-of-the-art PEMWEs are currently facing are excessive cost and poor durability. Understanding the failure modes in PEMWEs is a key factor for improving their durability, lowering the precious metal loading, and hence cost reduction. In this work, reactive spray deposition technology (RSDT) has been used to fabricate a membrane electrode assembly (MEA) with one order of magnitude lower Pt and Ir catalyst loadings (0.2-0.3 mgPGM cm-2) in comparison to the precious metal loadings in the stat-of-the-art commercial MEAs (2–3 mgPGM cm-2). As fabricated MEA with an active area of 86 cm2, has been tested for over 5000 hours at steady-state conditions that are typical for an industrial hydrogen production system. Herein, we present and discuss the results from a comprehensive post-test analysis of the MEA of interest. The main degradation mechanisms, governing the performance loss in the RSDT fabricated MEA with ultra-low precious metal loadings, have been identified and discussed in detail. All failure modes are critically compared and the main degradation mechanism with the highest impact on the MEA performance loss among the others is identified.

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