Direct Seawater Electrolysis for Decentralised Hydrogen Production: Opportunities for the Blue Economy

The blue economy is one of the most carbon-intensive sectors globally, with shipping alone emitting over 1000 Mt CO2 annually. Decarbonising it needs a clean, energy‑dense fuel, and green hydrogen has emerged as a leading option. However, existing electrolysis systems remain centralised, relying on freshwater and poorly suited to offshore conditions. Direct seawater electrolysis (DSE) resolves this by coupling offshore renewables with seawater to produce hydrogen directly at the point of demand. This eliminates the need for dedicated desalination, potentially reducing hydrogen production costs by up to 30%. Yet deployment is constrained by competing chlorine evolution, anodic corrosion, and cathodic hydroxide precipitation. In addition, scalable seawater electrolyser architectures remain underdeveloped. Advancing DSE requires integrating catalyst innovation with durable, environmentally robust system design. Here, we connect mechanistic strategies for mitigating cathodic precipitation with an ionically bonded heterostructure design principle for anodic OER-CER selectivity, and extend both to the underexplored challenges of intermittency and membrane durability. At scale, DSE could transform energy supply in the blue economy, enabling decentralised hydrogen production directly from seawater.