A comparative study of the electroreduction of polycrystalline and single crystal CdS electrodes: implications for h2 evolution in colloidal suspensions
✍ Scribed by I.J. Ferrer; M. Pujadas; P. Salvador
- Publisher
- Elsevier Science
- Year
- 1987
- Tongue
- English
- Weight
- 518 KB
- Volume
- 139
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
The cathodic decomposition of CdS, both polycrystalline and single crystal, has been studied by electrolyte electroreflectance, cyclic voltammetry and impedance measurements. With a defect-free single crystal, CdS electroreduction (surface deposition of Cd0 from lattice Cd2+ ions) has a very high overpotential (1.5-2.0 V). However, after photocorrosion or with polycrystalline electrodes the overpotential is reduced to 100-200 mV due to the accumulation of lattice defects at the electrode surface; reaction is thus possible even at potentials positive of the flatband. Simultaneous with Cd0 deposition, the energy levels of the semiconductor are shifted with respect to the electrolyte by 400 mV, conduction band electrons gaining energy to reduce water. Implications for hydrogen evolution at CdS particles are discussed.