Influence of PDS Loading Upon Type CD 1– x ZN x S Photocatalysts

In the last years, up to 90% of global energy demand for industrial and transportation sectors are supplied with fossil fuels, causing a high emission of greenhouse gases, including carbon dioxide and leading to a substantial depletion of carbon-based resources. A potential fuel for renewable energy is considered to be the hydrogen, besides to use of renewable energy based on solar, wind, geothermal and biomass. Up to now, CdS is the most important semiconductors with the 2.4 eV direct band gap that corresponds well with the maximum irradiation in the solar spectrum, and also has the advantage of a more negative conduction band edge compared to the H + /H 2 redox potential. In this paper, we reported the synthesis of Zn 2+ doped CdS with polymorphic crystallization using hydrothermal method at low temperature, without organic precursor used for water splitting. The products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and UV-visible diffuse reflectance spectra. From Tauc plot the optical energy gap for undoped CdS was found to be nearly to 2.28 eV and increase to 2.44 eV for Cd 0.5 Zn 0.5 S. From photoluminescence spectroscopy measurements showthe two broad emission peaks located at ~535 and ~595 nm which is high for samples Cd 0.8 Zn 0.2 S and Cd 0.8 Zn 0.5 S compared with samples CdS, Cd 0.7 Zn 0.3 S and Cd 0.6 Zn 0.4 S. The PL peaks indicates defects, however, the increment in the photoluminescence spectroscopy intensity indicates the higher amount of defects. The higher amount of defects and vacancies present in samples Cd 0.8 Zn 0.2 S and Cd 0.8 Zn 0.5 S is beneficial for the H 2 production rates. The H 2 production after 12 h of Cd 1– x Zn x S samples is 204 (μmol for undoped CdS and increase to 277 μmol for Cd 0.6 Zn 0.4 S and 384 μmol for Cd 0.5 Zn 0.5 S respectively. The effect of PdS on the photocatalytic properties of Zn 2+ doped CdS was investigated for hydrogen evolution under visible light from water containing Na 2 S and Na 2 SO 3 as sacrificial reagents. To our knowledge, the effect of PdS on the photoactivity of Zn 2+ doped CdS with polymorphic crystallization has not been reported before.