Photoelectrochemical Hydrogen Evolution Driven by Visible-to-Ultraviolet Photon Upconversion

Activation of ultraviolet (UV) energy bandgap semiconductors for solar fuel production using visible light as energy source is one of the most challenging tasks in the artificial photosynthesis field. Triplet–triplet annihilation (TTA) based on photon upconversion (UC) generates frequently high energy (i.e., UV) from lower energy (visible). Thus, an efficient and appropriate TTA-UC system can successfully use visible light to power a photoelectrochemical cell using TiO2, leading to photovoltages, photocurrents, and photoelectrocatalytic hydrogen production. Here, for the first time, visible-to-UV TTA-UC is demonstrated to be a useful strategy for performing artificial photosynthesis processes by means of UV energy bandgap semiconductors.