Seawater catalyst makes hydrogen peroxide and chlorine at once

Researchers in China and Australia built a Janus metal-organic framework catalyst that turns seawater into hydrogen peroxide and active chlorine in a single electrolysis system. The advance could help coastal regions make useful chemicals on site while avoiding freshwater use and costly separation steps.

Why it matters: - The catalyst turns seawater, an abundant but underused feedstock, into two industrial chemicals at once. - The system produces hydrogen peroxide and active chlorine, both used for bleaching, disinfection and water treatment. - The approach could support decentralized chemical production in coastal and island communities. - Using seawater instead of freshwater could reduce transport of hazardous chemicals and simplify local sterilization and remediation.

What happened: - Researchers led by East China Normal University, with The University of Queensland, Fuzhou University and Shanghai University, developed a Janus conductive metal-organic framework-on-conductive-metal-organic framework heterostructure. - The study was published Sept. 1, 2026 in eScience, Volume 6, Issue 5, Article 100581. - The catalyst enabled simultaneous seawater electrolysis to produce hydrogen peroxide at the cathode and active chlorine at the anode. - The original source URL is the published paper.

The details: - The catalyst uses a core-satellite design with positively charged Cu-HITP nanorods as the core and negatively charged Co-HHTP nanoparticles on the surface. - The surface charge contrast helps repel chloride ions at the cathode and attract chloride ions at the anode. - Cu–O–Co chemical bonds form at the interface between the two materials. - Cobalt sites preferentially adsorb oxygen for the two-electron oxygen reduction reaction. - Copper sites favor chloride adsorption for the chlorine evolution reaction. - Different Fermi levels drive electron transfer from Cu-HITP to Co-HHTP. - The resulting built-in electric field improves charge transfer across the heterointerface. - In simulated seawater, the catalyst reached 99.1% selectivity for hydrogen peroxide. - The chlorine evolution overpotential was 38 mV at 10 mA cm⁻². - The performance outpaced commercial dimensionally stable anodes. - In an integrated electrolyzer using real Bohai Sea water, the system produced 9.34 mol g_cat⁻¹ h⁻¹ of hydrogen peroxide and 9.26 mol g_cat⁻¹ h⁻¹ of active chlorine. - Faradaic efficiencies reached 95.1% for hydrogen peroxide and 94.3% for active chlorine. - The catalyst ran stably for more than 100 hours with minimal decay.

Between the lines: - The design solves a core seawater electrolysis problem: chloride ions are harmful at the cathode but essential at the anode. - Most seawater systems pair oxygen reduction with oxygen evolution, which yields lower-value oxygen instead of a useful co-product. - The Janus architecture gives each side of the catalyst a different function, which is the key engineering insight. - The result points to a practical route for making two high-value chemicals without freshwater or complex downstream separation.

What's next: - The in situ generated hydrogen peroxide and active chlorine were tested on dye pollutants and bacteria. - Both solutions decolorized methyl orange, methyl red and methylene blue within five minutes. - In tests against Escherichia coli, inhibition-zone radii grew from 20.0 mm to 44.9 mm as electrolysis time increased from 5 to 60 minutes. - The findings suggest a path toward on-site wastewater treatment and sterilization using only seawater, oxygen and electricity.

The bottom line: - A single seawater electrolyzer can now make two valuable chemicals efficiently, opening a new route for coastal chemical manufacturing and water treatment.