Key Takeaways & Executive Findings
- •• Rational design of chlorine-suppressing catalysts based on mechanistic insights. • Overview of recent advances in cutting-edge seawater electrolysis systems. • Discussion of challenges and potential directions for direct seawater electrolysis enhancement. • Simultaneous enhancement of Faradaic efficiency and reduction of electrolysis cost.
Abstract
Seawater electrolysis offers a promising pathway to generate green hydrogen, which is crucial for the net-zero emission targets. Indirect seawater electrolysis is severely limited by high energy demands and system complexity, while the direct seawater electrolysis bypasses pre-treatment, offering a simpler and more cost-effective solution. However, the chlorine evolution reaction and impurities in the seawater lead to severe corrosion and hinder electrolysis’s efficiency. Herein, we review recent advances in the rational design of chlorine-suppressive catalysts and integrated electrolysis systems architectures for chloride-induced corrosion, with simultaneous enhancement of Faradaic efficiency and reduction of electrolysis’s cost. Furthermore, promising directions are proposed for durable and efficient seawater electrolysis systems. This review provides perspectives for seawater electrolysis toward sustainable energy conversion and environmental protection.
1. Introduction
The renewable energy is experiencing rapid growth due to the global energy shortages and the environmental impact caused by fossil fuels [1–3]. The energy transitions are critical for alleviating energy crises, mitigating greenhouse gas emissions, safeguarding ecosystems, and promoting sustainable development [4]. Hydrogen is served as a clean and abundant energy carrier for energy storage and carbon dioxide emissions reduction [5, 6]. The demand of hydrogen is vigorously increasing due to energy demand and chemical reagent. The green hydrogen was generally defined as water electrolysis-derived hydrogen powered by renewable forces like wind and solar [7, 8], and it could generate minimal greenhouse gases during its production [9–11]. Therefore, the investment in renewable-powered water electrolysis technologies for green hydrogen production holds profound significance, as it drives the energy transition and supports carbon neutrality goals [11, 12].
However, water electrolysis, a key technology for clean energy generation, requires substantial freshwater resources. This raises concerns over the global distribution of freshwater and the exacerbation of water scarcity [13, 14]. In this context, the utilization of seawater for electrolysis presents a significant advantage by reducing the need for freshwater resources and leveraging the abundance of seawater. The seawater accounts for 96.5% of the Earth water and represented an almost inexhaustible resource and serves as a natural electrolyte, offering an ideal medium for the electrolysis process [15, 16].
There were two existing approaches for seawater electrolysis including indirect and direct methods [17]. Indirect seawater electrolysis requires seawater desalination before hydrogen production [18]. This approach mitigates the interference of seawater complex components during electrolysis. After extensive research, indirect seawater electrolysis has become a well-established and widely adopted technology [19]. However, the inherent need for an additional desalination step complicates the system, and the process does not fully eliminate residual ions. These residual ions can lead to corrosion or scaling, which deteriorates the electrolyzer performance by reducing efficiency and increasing maintenance requirements [20]. Moreover, desalination is energy-intensive, and it could bring high costs for the construction and maintenance of the complex systems in large-scale application [21–24]. In contrast, direct seawater electrolysis skips out the desalination stage, simplifying the hydrogen production process with reduced energy consumption and lower equipment and operational costs [25–27]. Furthermore, the vast availability of seawater resources globally makes direct seawater electrolysis a more efficient solution, particularly beneficial for arid coastal regions [19].
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Cenkai Zhao, Zheyuan Ding, Kunye Zhang, Ziting Du, Haiqiu Fang, Ling Chen, Hao Jiang, Min Wang, Mingbo Wu (2025). Comprehensive Chlorine Suppression: Advances in Materials and System Technologies for Direct Seawater Electrolysis. Nano-Micro Letters. https://doi.org/10.1007/s40820-025-01653-z
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Frequently Asked Questions
What is direct seawater electrolysis?
Direct seawater electrolysis is a method that uses seawater directly as the electrolyte without prior desalination, simplifying the hydrogen production process and reducing energy consumption and costs compared to indirect methods.
Why is chlorine suppression important in seawater electrolysis?
Chlorine evolution reaction and chloride-induced corrosion are major challenges in direct seawater electrolysis, as they reduce efficiency and damage electrodes. Suppressing chlorine is essential for durable and efficient hydrogen production.
What are the key advances in chlorine-suppressing catalysts?
Recent advances include rational design of catalysts based on mechanistic insights, such as tuning active sites to favor oxygen evolution over chlorine evolution, and developing materials with high selectivity and stability in chloride-rich environments.
What are the challenges for direct seawater electrolysis?
Challenges include managing pH fluctuations, impurities, and chloride-induced corrosion, as well as improving Faradaic efficiency and reducing system costs while maintaining long-term stability.
What is the significance of this review?
This review provides a comprehensive overview of recent progress in chlorine suppression and system design for direct seawater electrolysis, offering insights for sustainable energy conversion and environmental protection.
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