Seemingly small component changes can make a large impact on the productivity of electrochemistry systems, such as electrolyzers used for producing “green” hydrogen. For example, a new coating technology developed by Oxford nanoSystems Ltd. (OnS; Abingdon, U.K.; www.oxfordnanosystems.com), when applied to the electrodes of alkaline electrolyzers, can boost the electrical current flowing through the system, thereby increasing the rate of hydrogen production. “The resulting increase in production capacity lowers the CAPEX cost of alkaline electrolyzers by over 50%, relative to existing technologies. This very substantially reduces the cost of producing green hydrogen,” notes Ian Russell, CEO of OnS.
Historically, alkaline electrolyzers have relied on coating materials containing expensive platinum-group metals (PGMs) to enhance performance. However, the OnS coating, nanoFLUX, provides comparable performance to PGM-loaded coatings at a lower cost than conventional nickel-based electrodes, says Russell. Key to this performance is the coating’s dendritic structure that creates a network of microcavities on the substrate’s surface (photo) that significantly enhances the density of sites available for bubble formation. Additionally, the highly porous nature of nanoFLUX facilitates the release of bubbles and promotes surface re-wetting. This leads to a greater number of smaller bubbles being generated and expelled from the coated surface at an accelerated rate, thereby minimizing resistance and losses due to bubble buildup.
“Bubble release is critical because the electrochemistry reaction takes place where the liquid electrolyte is in contact with the solid electrode. Prior to their release from the electrode surface, gas bubbles form an insulating layer between solid and liquid, reducing the effective area of the electrode,” explains Russell.
For electrolyzer applications, the nanoFLUX coating has been combined with a proprietary non-PGM catalyst to activate the hydrogen-generation reaction. “The coating process is based on aqueous electrochemistry. The principal steps are the electroless deposition and growth of the nanoFLUX layer, followed by electroplating of the catalytic later. In addition, there are some surface-cleaning, preparation and rinsing steps within the overall process,” says Russell. OnS is currently operating a demonstration plant with the capability to coat electrodes up to 700 mm in diameter — similar in scale to those used in commercial systems — with plans to move to commercial production in 2025.