Main . The light-driven transformation of water into dihydrogen and dioxygen holds promise as a sustainable route to synthetic fuel1 , 2 , 3 , 4. Molecular catalysts for H 2 evolution have been synthetically tuned to achieve exceptional activity and/or low overpotentials, or even to perform both light harvesting and H–H bond formation in a single component to achieve integrated photoelectrocatalysis5 , 6 , 7 , 8 , 9 , 10. Molecular catalysts are prime subjec...