"In Rust we Shine": an all-in-one photo-electrocatalytic device for low-cost infrared-induced hematite's water-splitting with polymeric EVA film containing rare-earth up-conversion particles

Abstract

Handling and transforming solar radiation with spectral conversion luminescent materials constitutes a frontier approach in photonic research for advancing environmental catalysis and sustainable hydrogen production via photocatalytic water-splitting. In this study, a photon-assisted approach is used to enhance the photocatalytic activity of hematite (α-Fe2O3) photoelectrodes using Yb3+ and Er3+ co-doped NaYF4 particles. These particles emit intense green light through near infrared-to-visible up-conversion, with emission wavelengths well aligned with the bandgap of hematite, thereby optimizing photo-electrochemical water-splitting. Moreover, luminescent ethylene-vinyl acetate (EVA) films embedded with up-conversion particles were fabricated and utilized to manufacture laminated glass structures, with hematite coated on the opposite side. This all-in-one photonic device serves as a proof of concept for an industrially relevant platform enabling low-cost infrared-driven water-splitting. Photocurrent generation in this system is driven exclusively by mainly green upconverted photons under excitation from the 980-nm diode laser, which are absorbed by the hematite layer. The resulting up-converted green light coming out from the EVA film triggers surface oxidation on the hematite photocatalyst, demonstrating that water-spitting can be achieved through the up-conversion luminescence alone. Thus, we are proving that even with low energy green and red upconversion emission, it is possible to enable up-conversion driven water-splitting reactions.