Visible-light-driven CdS heterojunction photocatalysts of the MB degradation and water splitting

Chemical bath deposition (CBD) is used to prepare Cadmium Sulfide (CdS) nanocrystalline thin films on glass and FTO/glass substrates. The CdS/Au nanocrystalline thin films were prepare by casting a solution of Au nanoparticles made using pulsed laser ablation technique. The successive ionic layer adsorption and reaction (SILAR) approach was used to create SnS thin films on CdS thin films, resulting in CdS/SnS heterojunction nanocrystalline thin films. The optical properties of prepared samples indicated that the optical band gap of the CdS and CdS/SnS nanocrystalline thin films created on a glass substrate is 2.34 and 1.51 eV, respectively. The optical band gaps of the CdS, CdS/Au, and CdS/SnS nanocrystalline thin films formed onto FTO/glass substrates are predicted to be 2.36, 2.29, and 2.19 eV, respectively. The photocatalytic activity of the synthesized CdS and CdS/Au nanocrystalline thin films was tested against the methylene blue (MB) dye under visible light irradiation. The photodegradation rate of the MB dye rose as the irradiation period increased. After 240 min of exposure, the photodegradation rate of MB dye was 76 % and 96 % for CdS and CdS/SnS nanocrystalline thin films, respectively. The linear sweep voltammetry (J-V) of CdS, CdS/Au, and CdS/SnS nanocrystalline thin films on FTO/glass substrates demonstrated a strong sensitivity to visible light. The Niqyst measurements of the CdS/SnS nanocrystalline thin film electrode have the smallest semicircle when compared to the CdS and CdS/Au thin films.