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

Abstract

Handling and transforming solar radiation with spectral conversion luminescent materials constitute 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 a 980 nm diode laser, which are absorbed by the hematite layer. The resulting up-converted green light emitted 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 up-conversion emission, it is possible to enable up-conversion-driven water-splitting reactions.