18-Sep-2026
Chloride ions turn from foe to friend in seawater-to-hydrogen breakthrough
Science China PressPeer-Reviewed Publication
Solar-driven water splitting offers a carbon-neutral path to green hydrogen, but its reliance on freshwater has long raised sustainability concerns. Seawater — covering 97% of Earth’s water — presents an abundant alternative, yet its chloride ions have traditionally been seen as a major obstacle, causing corrosive side reactions and sluggish kinetics. Now, a team led by researchers at Shanghai Jiao Tong University has turned this challenge into an opportunity. They developed a noble-metal-free photocatalyst — MnOₓ(OH)y/GaN nanowires supported by a silicon wafer — that splits natural seawater efficiently under sunlight, achieving a solar-to-hydrogen efficiency of 6.15% without any sacrificial agents. The catalyst delivers a hydrogen production rate of 15.2 mol g−1 h−1 in natural seawater and operates stably for over 360 min. Surprisingly, the team discovered that chloride ions in seawater are not detrimental but actively beneficial: they reduce the Coulomb attraction energy between photogenerated electrons and holes, and simultaneously lower the energy barrier for water oxidation. Meanwhile, the hydroxyl groups inherent to the manganese oxyhydroxide cocatalyst undergo dynamic exchange with water molecules, further accelerating the formation of key reaction intermediates. Outdoor tests under concentrated natural sunlight confirmed the system’s practical feasibility.
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- Science Bulletin