β-carotene assisted chlorin-modified Pt/TiO2 photocatalysts for enhanced hydrogen evolution

The rational design of hybrid nanostructure photocatalysts with efficient charge separation and transfer, and a wide range of sunlight harvesting ability is crucial for achieving high light-to-chemical energy conversion efficiency. Herein, we demonstrate a straightforward dye-coating method of Pt/TiO2 with chlorophyll derivatives and beta-carotene (Car) to prepare hybrid photocatalysts as mimicking the natural photosynthetic systems utilizing chlorophylls and carotenoids cooperatively. A series of carboxylated-chlorins (Chls) were chemisorbed on Pt/ TiO2, followed by lipophilic Car loading via solvent evaporation, creating Car/Chl@Pt/TiO2 nanocomposites for photocatalytic hydrogen evolution. We hypothesize that Car, interacting with Chls through hydrophobic forces, acts as a redox spacer, preventing reverse electron transfer from TiO2 to Chls and enhancing photocatalytic performance for hydrogen evolution reaction. The optimal catalyst, Chl with a lipophilic side chain and one molar equivalent of Car, achieved a remarkable activity of 41.7 mmol h- 1 g- 1. This sequential dye-coating strategy for inorganic Pt/TiO2 nanoparticles is a promising route to enhance photocatalysis and informs the development of novel organic-inorganic hybrid photocatalysts.