There's Still Plenty to Do in Photocatalysis.

Photocatalysis has undeniable promise for enabling chemical synthesis in a post-fossil resource future; however, this promise has yet to be realized at scale despite over 100 years of interest. Here I propose that this relatively slow progress is rooted in the high chemical complexity of photocatalytic reactions. While the complexity of light absorption and excited state chemistry is a key contributor, our research on Fe/S photocatalysis implicates the efficiency of the many thermal, dark elementary steps being the primary challenge for making a functional reaction. These experiences suggest a paradoxical opportunity in photocatalysis research: one of the richest, most enabling, and most underexplored areas of research is the study of non-photocatalytic steps.