“There is plenty of energy at the bottom”: A spectral conversion approach for upconversion-powered water-splitting PEC cell

An avant-garde step towards the use of the long infrared tail of the incident solar radiation with untapped and crucial applications in photocatalysis and energy harvesting schemes is presented: “there is plenty of energy at the bottom”. In detail, a pure photonic approach to enhance titanium dioxide (TiO 2 ) photocatalytic activity is proposed, by using rare-earth doped luminescent glassy materials, capable of performing NIR-to-UV-VIS spectral conversion (up-conversion). Therefore we report infrared-driven boosting of green hydrogen production in a photo-electrochemical water-splitting cell using TiO 2 electrodes, revisiting the original design of Fujishima and Honda fifty years later. This proof-of-concept comprises infrared-induced hydrogen and oxygen evolution via water-splitting and determines univocally the role of a solely photonic effect to split water. Thus, the conversion of the incident NIR radiation, before its interaction with the photocatalyst, emerges as a significant contribution to the state-of-the-art for an effective harvest of the near-infrared portions of sunlight. “There is plenty of energy at the bottom”: revisiting Fujishima-Hondás photoelectrochemical cell with spectral conversion approach: up-conversion driven hydrogen generation for envisioned harnessing of large infrared sun's tail. • Proof-of-concept experimental of a complete functional infrared-activated PEC cell. • Up-conversion luminescent approach for extending spectral response of semiconductor. • Verification of the sole role of photonic effect on infrared-driven photocatalysis.