Au-decorated Sb2Se3 photocathodes for solar-driven CO2 reduction†

Photoelectrodes with FTO/Au/Sb₂Se₃/TiO₂/Au architecture were studied in photoelectrochemical CO₂ reduction reaction (PEC CO₂RR). The preparation is based on a simple spin coating technique, where nanorod-like structures were obtained for Sb₂Se₃, as confirmed by SEM images. A thin conformal layer of TiO₂ was coated on the Sb₂Se₃ nanorods via ALD, which acted as both an electron transfer layer and a protective coating. Au nanoparticles were deposited as co-catalysts via photo-assisted electrodeposition at different applied potentials to control their growth and morphology. The use of such architectures has not been explored in CO₂RR yet. The photoelectrochemical performance for CO₂RR was investigated with different Au catalyst loadings. A photocurrent density of ∼7.5 mA cm⁻² at −0.57 V vs. RHE for syngas generation was achieved, with an average Faradaic efficiency of 25 ± 6% for CO and 63 ± 12% for H₂. The presented results point toward the use of Sb₂Se₃-based photoelectrodes in solar CO₂ conversion applications.