It is necessary to separate the photocatalyst by centrifugation or filtration, which might lead to metal agglomeration and significant losses, which would reduce activity . The recyclability of the photocatalyst was examined over the course of four consecutive cycles as seen in Figure -IV. After the photocatalytic reaction, little metal loss is observed and the decrease in photocatalytic performance was caused by photocorrosion (S 2-oxidised following long-term irradiation by photogenerated holes, resulting in photocatalyst failure) . After four runs, SO-CdS preserved 85.11% of its initial photocatalytic hydrogen evolution activity. Na2S, a sacrificial agent, chemically absorbs CO2 and allows hydrogen to evolve .