Advances in noble-metal-free electrocatalysts for alkaline seawater electrolysis: General mechanisms, challenges, and strategic innovations

The rising global demand for energy and the climate crisis caused by fossil fuel combustion require an immediate shift toward renewable energy sources. Seawater electrolysis offers a sustainable method for producing green hydrogen by utilizing abundant ocean resources in direct conjunction with renewable power inputs. Green hydrogen has surfaced as a key energy carrier with minimal intermittent losses in transport and power generation. Nevertheless, the ionic composition of seawater affects efficiency, electrocatalyst stability, and operational costs. Specifically, the chloride oxidation reaction occurring at the anode presents a serious risk to the integrity of electrodes and the long-term functionality of devices. This review encapsulates the essential mechanisms of seawater electrolysis, the criteria for assessing electrocatalyst performance in renewable energy systems, and the unique challenges associated with noble-metal-based electrodes. Recent progress in noble-metal-free composite electrocatalysts through techniques such as heterostructure engineering, metal doping, protective coatings, and anion intercalation, all of which collectively increase resistance to chloro-oxidation and increase durability, has also been emphasized. By bringing together these advancements, this review offers a technological framework for incorporating seawater electrolysis into renewable energy infrastructure, facilitating efficient hydrogen production in challenging marine environments, ensuring reliable energy storage, and furthering the global effort toward a carbon-neutral future.