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Role of aliovalent cation doping in the activity of nanocrystalline CdS for visible-light-driven H2 production from water
- Source :
- International Journal of Hydrogen Energy. 40:8695-8705
- Publication Year :
- 2015
- Publisher :
- Elsevier BV, 2015.
-
Abstract
- This study was aimed at discerning the enhancement in the visible-light–driven water splitting activity of nanocrystalline CdS photocatalysts because of their doping with a small amount of an aliovalent cation (Ag+ or Cr3+). The CdS/Cr-x (x = 0–2.3 wt%) and CdS/Ag-x (x = 0–1.5 wt%) samples, which were synthesized using a one-step hydrothermal method, were characterized systematically for their crystallographic, morphological, interfacial, and photo-physical properties. The Rietveld refinement of the powder X-ray diffraction data enabled us to quantify the doping-effect on the phase composition and lattice parameters. As compared to pure CdS, the samples containing ∼0.2 wt% of Cr or Ag showed two or tenfold enhancement in the rate of H2 evolution from water, respectively, when sulfide-sulfite ions were used as sacrificial electron donors. This pyramidal trend, i.e. maximum activity for a specific impurity content, which decreased on decreasing as well as increasing the amount of doping, did not occur owing to the presence of a secondary-phase metal sulfide or a dispersed metal cocatalyst. Our study revealed that instead of the widely advocated mechanism involving inter-semiconductor or semiconductor-to-metal electron transfer steps, the doping-modified photoactivity of CdS was governed by certain bulk and surface properties such as the cation-dependent particle nucleation, dominance of hex-CdS facets, and structural defects. Additionally, impurity-induced sub-bandgap charge-trapping states also contributed to the overall quantum efficiency.
- Subjects :
- chemistry.chemical_classification
Materials science
Sulfide
Renewable Energy, Sustainability and the Environment
Rietveld refinement
Inorganic chemistry
Doping
Energy Engineering and Power Technology
Condensed Matter Physics
Nanocrystalline material
Metal
Electron transfer
Fuel Technology
chemistry
Impurity
visual_art
visual_art.visual_art_medium
Water splitting
Subjects
Details
- ISSN :
- 03603199
- Volume :
- 40
- Database :
- OpenAIRE
- Journal :
- International Journal of Hydrogen Energy
- Accession number :
- edsair.doi...........bb55cbdd3966110932c148f1ea9f9db0