Triplet-Triplet Annihilation Upconversion for Photocatalytic Hydrogen Evolution

The solar generation of hydrogen by water splitting provides a promising path for renewable hydrogen production and solar energy storage. Upconversion of low-energy photons into high-energy photons constitutes a promising strategy to enhance the light harvesting efficiency of artificial hydrogen production systems. In the present study, upconversion micelles are integrated with Cd0.5Zn0.5S to construct solar energy conversion systems. The upconversion micelle is employed to upconvert red photons to cyan photons. Cd0.5Zn0.5S is sensitized by upconverted cyan light to produce hydrogen, but not by incident red light without triplet-triplet annihilation upconversion (TTA-UC). The performance of the upconversion photocatalytic system was dramatically affected by the concentration of Cd0.5Zn0.5S and the irradiation intensity. This novel system was able to produce about 2.3 mu L hydrogen after 5h of red light (629nm) irradiation (2.4mWcm(-2)). The present study provides a candidate for applications using low-energy photons for solar hydrogen generation.