The transition to sustainable energy technologies relies heavily on water electrolysis. Using the Earth’s abundant seawater instead of increasingly scarce freshwater is a highly attractive solution. However, seawater contains complex and aggressive components, primarily corrosive chloride ions. These ions trigger severe parasitic side reactions at the anode and induce the rapid structural collapse of oxygen evolution reaction (OER) electrocatalysts. Consequently, ensuring the long-term service of these materials in marine environments remains a critical bottleneck.
To address this structural degradation challenge, a collaborative research team led by Prof. Jinchun Tu and Prof. Weiwei Li from Hainan University, alongside Prof. Chenghua Sun from Swinburne University of Technology, has successfully engineered a highly durable electrocatalyst specifically designed for harsh seawater oxidation. Their findings have been published in Science Bulletin .
The research team focused on high-entropy selenide (HES) materials. By strategically introducing trace amounts of interstitial boron into the high-entropy matrix, they developed a modified catalyst (B-HESs) with distinct anti-corrosion properties and long-term structural retention.
The extended durability of this catalyst originates from an integrated dual-protection mechanism. During the harsh seawater electrolysis process, the active transition metal sites undergo dynamic valence oscillations, a continuous redox cycling. This localized structural self-repair prevents the active sites from irreversible over-oxidation and subsequent structural breakdown. Simultaneously, this dynamic process facilitates the formation of a robust, negatively charged selenate shielding layer on the catalyst surface. This layer strongly repels destructive chloride ions through electrostatic repulsion and steric hindrance, effectively preventing the continuous leaching of internal metal elements.
In highly corrosive simulated seawater, the B-HESs anodic catalyst sustained continuous and stable oxygen evolution for over 1000 hours at a high industrial current density of 500 mA cm − 2 . Furthermore, it exhibited excellent catalytic kinetics, requiring a low overpotential to drive the reaction, and maintained nearly 100% selectivity for OER, effectively suppressing the toxic chlorine evolution reaction.
“This dynamic self-stabilizing mechanism successfully circumvents the fundamental trade-off between catalytic activity and long-term stability,” noted the research team. “It provides a practical material design strategy for realizing durable electrolysis directly from seawater.”
This mechanistic insight not only advances the field of direct seawater electrolysis but also provides valuable guidelines for designing robust electrocatalysts capable of surviving other extreme and corrosive electrochemical environments.
Science Bulletin
Experimental study