They say opposites attract, and many couples do fit this pattern. One is pragmatic and down-to-earth, while the other is a dreamer with their head in the clouds. Yet, these differences make them perfect for each other. According to researchers at ICFO, chemical interactions between atoms are not that different. Ruthenium, for instance, belongs to the "dreamer" class. It is commonly used in single-atom catalysts that speed up water electrolysis, which splits water to obtain green hydrogen. However, on its own, ruthenium tends to over-oxidize and dissolve during operation, like an idealist who takes flight without looking back.