Single‐Atom Ruthenium Sites on Cobalt‐Titanium Surfaces for Efficient and Selective Chloride Electrolysis

Why It Matters

The breakthrough lowers the cost and energy demand of chlorine electrolysis, enabling more sustainable seawater desalination and water treatment. Its high selectivity and stability accelerate deployment of carbon‑neutral electrochemical processes.

Key Takeaways

• Ru single-atoms dispersed on Co2TiO4/Ti support
• Overpotential 26.2 mV at 10 mA cm⁻²
• 87% chlorine selectivity in seawater-like media
• Ru loading below 0.1% reduces material cost
• Proton‑independent kinetics across pH 4.5‑9

Pulse Analysis

Seawater electrolysis, particularly the chlorine evolution reaction (CER), is a cornerstone of large‑scale water treatment and chlorine production. Conventional catalysts rely on bulk ruthenium oxides, which drive high overpotentials and inflate material costs, limiting the economic viability of green hydrogen and chlorine pathways. In recent years, single‑atom catalysts have emerged as a promising route to maximize metal utilization while tailoring electronic structures for specific reactions. By isolating active sites at the atomic level, researchers can achieve unprecedented activity, selectivity, and durability, addressing the twin challenges of efficiency and sustainability.

The new Ru(SA)–Co₂TiO₄/Ti catalyst exploits a Ru‑EDTA complex to anchor Ru atoms within the orthorhombic Co₂TiO₄ lattice, preventing agglomeration during calcination. With a ruthenium loading of only 0.08 mg cm⁻² (<0.1 wt %), the material reaches an overpotential of 26.2 mV at 10 mA cm⁻² and a Tafel slope of 39.2 mV dec⁻¹, outperforming state‑of‑the‑art CER systems. Electrochemical tests in sodium chloride solutions that mimic seawater show 87 % chlorine selectivity and stable operation over extended periods. XANES and EXAFS confirm mixed‑valence Ru³⁺/Ru⁴⁺ coordinated by oxygen, while induced Coδ⁺ and oxygen vacancies enhance chloride adsorption and promote a proton‑independent reaction pathway.

The implications extend beyond laboratory metrics. By dramatically reducing ruthenium consumption and operating voltage, the catalyst cuts both capital and operational expenditures for chlor‑alkali plants and offshore desalination units. Its robust performance across a wide pH range simplifies integration with existing electrolyzer designs, accelerating the transition to carbon‑neutral water infrastructure. Moreover, the scalable Ru‑EDTA synthesis offers a template for other single‑atom systems targeting diverse electrochemical processes, positioning the technology as a strategic asset for the renewable energy and chemical manufacturing sectors.