Researchers from the Fritz Haber Institute of the Max Planck Society have unveiled new insights into the activity of catalysts used in green hydrogen production. © FHIIntroduction to Catalyst Activity The Department of Interface Science at the Fritz Haber Institute has made significant strides in understanding how catalysts function in aqueous environments. This research is crucial for advancing technologies like green hydrogen production, which relies on efficient catalysts to split water molecules. This reaction is a bottleneck in water electrolysis, where sluggish OER kinetics can hinder hydrogen production. This indicates that the catalyst's activity is intrinsically linked to its ability to build-up excess charge to interact with solvated ions from the liquid electrolyte.