High-performance Sb2S3 photoanode enabling iodide oxidation reaction for unbiased photoelectrochemical solar fuel production

Abstract

The traditional photoelectrochemical (PEC) tandem configuration of hydrogen evolution reaction and oxygen evolution reaction (OER) demands a considerable potential of 1.8 V due to theoretical water splitting potential as well as a large overpotential mainly derived by sluggish OER kinetics. The iodide oxidation reaction (IOR) is a promising alternative to OER due to its low thermodynamic energy and two-electron-involved fast reaction kinetics. Herein, we report a high-performance catalyst-modified Sb₂S₃ photoanode to drive IOR. A compact thin-film-type Sb₂S₃ absorber is fabricated via solution processing based on a thorough understanding of the molecular interaction in the precursor ink state. Moreover, the deposition of a multilayered catalyst RuO₂ nanosheet and polydiallyldimethylammonium chloride not only efficiently enhances the charge transfer kinetics but also passivates the surface defects of the Sb₂S₃ absorber. The resulting photoanode exhibits an efficient photocurrent density of 10 mA cm⁻² at 0.54 V compared to the normalized hydrogen electrode in hydroiodic acid. In conclusion, we demonstrate a bias-free PEC tandem device based on a RuO₂-modified Sb₂S₃ photoanode paired with a silicon photocathode, yielding an operation current density of 4 mA cm⁻².