A corrosion-resistant RuMoNi catalyst for efficient and long-lasting seawater oxidation and anion exchange membrane electrolyzer

TLDR

Seawater electrolysis is promising for sustainable hydrogen production, but chloride ions cause side reactions and corrosion that lower efficiency and stability, hindering its practical use. The authors aim to develop a corrosion‑resistant RuMoNi electrocatalyst for seawater oxidation. The catalyst incorporates in‑situ formed molybdate ions on its surface that repel chloride ions, enhancing durability. The RuMoNi catalyst remains stable for over 3000 h at 500 mA cm⁻² in alkaline seawater, achieves 77.9 % energy‑conversion efficiency at 1.72 V and 1000 mA cm⁻², and yields hydrogen at a cost of $0.85 GGE, below the DOE 2026 target.

Abstract

Direct seawater electrolysis is promising for sustainable hydrogen gas (H2) production. However, the chloride ions in seawater lead to side reactions and corrosion, which result in a low efficiency and poor stability of the electrocatalyst and hinder the use of seawater electrolysis technology. Here we report a corrosion-resistant RuMoNi electrocatalyst, in which the in situ-formed molybdate ions on its surface repel chloride ions. The electrocatalyst works stably for over 3000 h at a high current density of 500 mA cm-2 in alkaline seawater electrolytes. Using the RuMoNi catalyst in an anion exchange membrane electrolyzer, we report an energy conversion efficiency of 77.9% and a current density of 1000 mA cm-2 at 1.72 V. The calculated price per gallon of gasoline equivalent (GGE) of the H2 produced is $ 0.85, which is lower than the 2026 technical target of $ 2.0/GGE set by the United Stated Department of Energy, thus, suggesting practicability of the technology.