Visible light-driven simultaneous water oxidation and quinone reduction by a nano-structured conjugated polymer without co-catalysts† †Dedicated to Pr. Jean-Jacques Girerd for his 70th birthday. ‡ ‡Electronic supplementary information (ESI) available: Experimental details, additional reference experiments, spectroscopic and structural results. See DOI: 10.1039/d0sc02122a

Nanostructured conjugated polymers of diphenylbutadiyne (nano-PDPB) can perform photocatalytic water oxidation under visible light excitation. Charge recovery delayed in time was exemplified by the reduction of quinone acting as a hydrogen reservoir. In artificial photosynthesis, chemists are aiming to borrow principles from natural photosynthesis to develop photoelectrochemical cells (PEC) for water splitting. The water plastoquinone photo-oxidoreductase enzyme, also known as photosystem II, uses light to perform the four-electron, four-proton oxidation of water to dioxygen and stores reducing equivalents in reduced forms of quinones which are ultimately used in dark reactions for the synthesis of energy-rich molecules. We report a nano-structured semiconducting conjugated polymer based on poly(diphenylbutadiyne) (nano-PDPB) and its photocatalytic activities towards the water oxidation reaction under visible light irradiation when dispersed in water in the absence of any sacrificial agents or co-catalysts. Charge recovery at the nano-PDPB directly or delayed in time was exemplified by the reduction of quinone acting as a hydrogen reservoir. In the absence of quinones as electron acceptors H 2 O 2 formation was detected, stemming from the partial reduction of O 2 .