A single-layer ruthenium oxide catalyst cuts energy loss in hydrogen production and operates for more than 1,100 hours.
A team led by Soochow University in China has developed a ruthenium oxide catalyst just one atomic layer thick to reduce the energy required for splitting water in acidic conditions. The work involved collaborators from the Hong Kong Polytechnic University, Xiamen University, the University of Science and Technology of China and the National Synchrotron Radiation Research Center in Taiwan. The catalyst targets the anode of a proton-exchange-membrane (PEM) electrolyser, where the oxygen evolution reaction is a major contributor to the energy required for green hydrogen production.
Conventional ruthenium dioxide crystallises in the rutile structure, where neighbouring RuO6 octahedra are connected through shared corners. The team instead produced a 1T-phase single layer in which adjacent octahedra share edges. This edge-sharing arrangement brings the ruthenium 4d orbitals of neighbouring clusters into parallel alignment, allowing electrons to move more easily between catalytic sites.
This matters because the oxygen evolution reaction (OER) is the slower half of water splitting. Its sluggish kinetics force an electrolyser to operate at a voltage higher than the thermodynamic requirement, creating an energy loss known as overpotential. Improved electron transport between catalytic sites helps reduce this loss.
The catalyst reaches an overpotential of 77 mV at a current density of 10 mA/cm². Its mass activity reaches 3,743 A/g of ruthenium, while the turnover frequency is 23.99 per second at 1.50 V against the reversible hydrogen electrode. In a full proton-exchange-membrane electrolyser cell, the material maintained a current density of about 2.9 A/cm² at 1.70 V for more than 1,100 hours.
Commercial proton-exchange-membrane electrolyser anodes commonly use iridium-based catalysts because of their stability in acidic conditions, although iridium is scarce and expensive. The 77 mV result represents the performance of the new catalyst under the study’s specified testing conditions. Lowering anode overpotential reduces the voltage required for hydrogen production, directly reducing electricity consumption. A single-layer catalyst could also reduce the amount of precious metal required per unit electrode area.
This is a laboratory-scale catalyst demonstrated in a single-cell PEM electrolyser. The more than 1,100-hour operating test provides a meaningful indication of durability beyond a short polarisation measurement. However, the demonstration remains limited to a single cell rather than a multi-kilowatt electrolyser stack, and scaling the synthesis of the single-layer material to electrode-sized areas has yet to be demonstrated. According to the researchers, the edge-sharing configuration is central to the catalyst’s performance, making reliable reproduction of this phase at larger scales a critical challenge.
India’s National Green Hydrogen Mission has an outlay of 19,744 crore rupees and aims to build capacity for five million tonnes of green hydrogen production annually by 2030. The Strategic Interventions for Green Hydrogen Transition, or SIGHT, programme supports domestic electrolyser manufacturing. Government allocations under the programme have supported 3,000 MW of annual electrolyser manufacturing capacity, covering both alkaline and PEM technologies.
India’s domestic PEM supply chain remains more dependent on imported platinum-group-metal materials and specialised components than the alkaline route. A catalyst chemistry that reduces precious-metal use at the anode could therefore improve the material economics of PEM electrolysers. PEM systems can also respond rapidly to changing power input, making them well suited to applications involving variable renewable electricity.
If PEM electrolysers become cheaper and less dependent on scarce catalyst materials, India’s expanding solar capacity could become a more practical source of hydrogen for major industrial consumers, including refineries and fertiliser production. The result reported here is still at the catalyst research stage, but reducing anode catalyst cost and improving durability addresses an important challenge in expanding PEM electrolyser deployment.
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