https://en.m.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust https://en.m.wikipedia.org/wiki/Abundance_of_elements_in_Ear... Ruthenium and Iridium

https://en.m.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust https://en.m.wikipedia.org/wiki/Abundance_of_elements_in_Ear... Ruthenium and Iridium are known stable catalysts that are also among the most rare elements. Their structure used Ru. This new paper seems to propose only abundant materials. If it can be used at scale and proves to be stable that would be an important advancement.