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 (PEC) 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.