Antimony(III) Sulfide Thin Films as a Photoanode Material in Photocatalytic Water Splitting

For the first time, we present exploratory investigations on the performance of thermally evaporated Sb2S3 thin film photoanodes for solar-assisted water-splitting applications. With a band gap of 1.72 eV, a 250 nm thick Sb2S3 photoanode showed a saturation photocurrent density of ∼600 μA cm–2 measured at 1.0 V reversible hydrogen electrode (RHE) in 0.1 M Na2SO4 under 1-sun illumination, with an onset potential of ∼0.25 V RHE. However, subsequent photodegradation studies revealed that the material dissolves relatively quickly with the application of both illumination and bias. Nonetheless, Sb2S3 does have the advantage of having a relatively low optimal fabrication temperature of 300 °C and thus may have utility as a top cell absorber of a tandem device where the bottom cell is temperature sensitive, if protected from corrosion. Therefore, we characterized relevant aspects of the material in an attempt to explain the large difference between the theoretical maximum and measured current density. From our characterization it is believed that the photocatalytic efficiency of this material can be improved by modifying the surface to reduce optical reflection and addressing inherent issues such as high electrical resistivity and surface defects.