Cathode overcomes key challenges in water electrolysis for clean energy

A new kind of cathode that is more resistant to power fluctuations can render (sea)water electrolysis more sustainable, cost-effective, and more suited for coupling with intermittent renewable energy in real-world applications, according to scientists at City University of Hong Kong (CityUHK).

The system operates stably for 10,000 hours, longer than most previous methods, even when the energy supply fluctuates, such as from solar or wind, helping move toward a carbon-free future.

“Our work mainly addresses what’s called oxidation and performance loss issues during intermittent alkaline (sea)water electrolysis, such as reverse currents, self-oxidation, self-discharge, or oxygen crossover, using a special protective layer on the electrodes,” explains Professor Liu Bin from the Department of Materials Science and Engineering.

The benefit of the study, which has been published in Nature, is that the findings point toward making (sea)water electrolysis scalable and practical.

“The technology works at industrial-scale current levels and can withstand harsh conditions, making it suitable for large-scale deployment. It is specifically designed to address scientific challenges in real-world applications,” he says.

The self-healing cathode addresses a key reactor engineering challenge: maintaining electrolyzer stability under intermittent conditions, i.e., when the sun doesn’t shine or the wind drops. This advancement mitigates electrode degradation issues in anion exchange membranes and alkaline electrolyzers when coupled with fluctuating renewable energy sources.

More importantly, the study draws attention to the often-overlooked issues of electrolyzers under realistic, variable working conditions and calls for collective efforts to tackle the scientific and technical challenges of intermittent electrolysis.

“This work lays a foundation for more resilient systems and accelerates the development of the green hydrogen industry,” Professor Liu adds.

Furthermore, future electrocatalytic systems for chemical and fuel synthesis, such as oxygen reduction reaction, CO₂ reduction and nitrogen reduction, will face similar shutdown and start-up issues when paired with renewable energy sources.

The insights from water electrolysis under fluctuating conditions today can be extended to these systems, helping ensure that a broad range of future electrochemical technologies can be effectively integrated into renewable energy grids, accelerating progress toward net-zero.

“This research brings us closer to clean, sustainable energy powered by green hydrogen, replacing fossil fuels in areas such as transportation and the home. It supports a future that will be characterized by clean energy that is affordable, accessible, and available to everyone, leading to improved health, a better protected environment, and ‘green’ jobs,” he adds.