Au-decorated Sb 2 Se 3 photocathodes for solar-driven CO 2 reduction.

Photoelectrodes with FTO/Au/Sb 2 Se 3 /TiO 2 /Au architecture were studied in photoelectrochemical CO 2 reduction reaction (PEC CO 2 RR). The preparation is based on a simple spin coating technique, where nanorod-like structures were obtained for Sb 2 Se 3 , as confirmed by SEM images. A thin conformal layer of TiO 2 was coated on the Sb 2 Se 3 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 CO 2 RR yet. The photoelectrochemical performance for CO 2 RR 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 H 2 . The presented results point toward the use of Sb 2 Se 3 -based photoelectrodes in solar CO 2 conversion applications.