We also consider here the relative prevalence of elements in catalysts used for green hydrogen production on a document-level basis, shown below in Figure . This provides a rough landscape for assessing the overall elemental distribution of research interest and may point to future resource requirements for adoption on a societal scale. Overall, emphases on carbonaceous materials as well as transition metal oxides and sulfides are evident. There has been strong interest in critical metals including cobalt, nickel, and platinum, with the peak publication volume centered at the expected d 8 transition metals typical of HER catalysts.