Hydrogen production from seawater electrolysis: Challenges, strategies and future

As the world grapples with the intertwined challenges of climate change and energy scarcity, the quest for sustainable energy solutions has never been more critical. The large-scale generation of green hydrogen through the electrolysis of water using renewable energy sources is emerging as a pivotal strategy in our global transition to a low-carbon future. Green hydrogen, derived from the electrolysis of water powered by renewable energy such as wind, solar, and geothermal sources, represents a paradigm shift in clean energy production due to its minimal greenhouse gas emissions. The allure of green hydrogen lies in its potential to decarbonize a variety of sectors, including transportation, industry, and power generation, which are currently heavily reliant on fossil fuels. However, the journey towards the widespread adoption of green hydrogen is not without obstacles. The shortage of fresh water may become a bottleneck for large-scale industrial hydrogen production. Due to the abundant seawater resources, the use of low-grade water sources such as seawater for electrolysis is a promising path. However, it also faces a complex set of challenges. The complex matrix of seawater, which is rich in salts, minerals, and microorganisms, introduces a myriad of issues that can impede the efficiency and longevity of electrolytic systems. The propensity for chlorine ions to be oxidized into Cl₂ or ClO⁻ during electrolysis not only competes with oxygen production but also poses a risk of corrosion to the equipment. Furthermore, the presence of suspended particles and microorganisms in seawater can lead to the clogging of electrolytic cells, which in turn affects the overall efficiency of the electrolysis process. These factors have raised legitimate concerns about the durability of electrocatalysts and the robustness of electrolytic systems, casting a shadow on the practicality and economic viability of large-scale seawater electrolysis for hydrogen production. Despite these hurdles, the scientific community is actively engaged in innovative research and development to address these challenges. Technological advancements in electrocatalyst design have led to the creation of materials that can withstand the harsh conditions of seawater electrolysis, offering improved stability and longevity. Moreover, the engineering of electrolyzers has also undergone significant progress, with novel designs aimed at mitigating issues such as fouling and corrosion. This review paper delves into the intricacies of seawater electrolysis, examining the underlying principles and the multifaceted challenges that accompany this process. It provides a comprehensive overview of the current state of research, highlighting breakthroughs in the development of electrocatalysts tailored for the oxygen evolution reaction at the anode. These catalysts are crucial for enhancing the kinetics of the reaction, thereby reducing the energy input required for electrolysis and improving the overall efficiency of hydrogen production. In addition to electrocatalyst advancements, the paper also explores the latest trends in electrolyzer design, which are pivotal for the practical implementation of seawater electrolysis technology. Innovations in materials, membrane technology and electrolyzer structures are discussed, emphasizing how these contribute to the enhanced performance and economic competitiveness of electrolysis systems. As the discourse progresses, the paper shifts its focus to the future landscape of seawater electrolysis for hydrogen production. The journey towards a sustainable energy future, underpinned by the large-scale production of green hydrogen, is both challenging and promising.