Substance information found within publications provides additional insights. While publication volume alone provides a picture of relative research interest over time, it does not detail the diversity of approaches being taken to a given topic. Analysis of relevant substance classes within this progression over time reveals several research trends. For example, the increase in compounds of classes Alloy and Element show the exploration of chemical space for alternative electrocatalysts to Pt 10 and as components in composite materials as electro-and/or photocatalysts. Coordination compounds, on the other hand, saw an increase in material diversity in the first half of the decade followed by sustained research interest.