Author: Milutin Smiljanić (National Institute of Chemistry) - The excessive use of fossil fuels has caused severe environmental issues, including global warming, air pollution, and human health issues. As the world transitions to cleaner energy, hydrogen is emerging as a key energy carrier. When produced via renewable-powered water electrolysis, green hydrogen offers a carbon-free alternative for transportation, industry, and power generation. In electrolyzers, hydrogen is generated through the electrochemical hydrogen evolution reaction (HER), coupled with the oxygen evolution reaction (OER) to complete water splitting. The efficiency of this process depends on the activity, durability, and cost of HER and OER electrocatalysts. Currently, Pt and IrOx are state-of-the-art catalysts for HER and OER, but their scarcity and high cost hinder commercialization of these devices. Thus, developing alternative, cost-effective catalysts is crucial for widespread usage of water electrolyzers.
This study presents Ru supported on a titanium oxynitride–carbon template (Ru/TiON-C) as an efficient catalyst for water splitting with an exceptionally low Ru loading (6 wt.%). Ru is the most affordable platinum-group metal, and its low usage in Ru/TiON-C offers a major economic advantage over commercial Pt/C and IrOx. Ru/TiON-C demonstrated superior HER activity, particularly in alkaline media, surpassing Ru/C and Pt/C analogs in mass activity and metal utilization. The TiON support provides metal-support interaction (MSI) with Ru sites, optimizing hydrogen adsorption/desorption and water dissociation—key parameters in HER reactivity. Additionally, Ru/TiON-C showed promising OER features, significantly improving metal utilization over unsupported IrOx, though further optimization of the catalyst is needed. Given the beneficial MSI effects of TiON on low-loaded Ru catalysts, this study opens new avenues for highly active, cost-effective electrocatalysts in overall water splitting.