Photoassisted hydrogen evolution over spinel CuM2O4 (M=Al, Cr, Mn, Fe and Co)

S. Saadi, A. Bouguelia and M. Trari

Renewable Energy, 2006, vol. 31, issue 14, 2245-2256

Abstract: The photocatalytic ability of CuM2O4 (M=Al, Cr, Mn, Fe and Co) crystallizing with spinel-type structure has been evaluated according to the H2-evolution. The oxides are black and displayed a semiconducting behavior where the electronic balance comes from a small over stochiometry (CuCo2O4.016). Electron hopping occurs between similar sites in normal spinel with a low activation energy whereas larger energies were found in inverse spinel. The electrodes were characterized photoelectrochemically and acquired the characteristic of p-type semiconductors. The conduction band edge, determined from intensity–potential curves, is located below the H2O/H2 potential leading to a thermodynamically favorable H2-liberation under visible light. The photoactivity was dependent on preparative conditions and the best results were obtained over CuCo2O4 prepared through nitrate route in presence of SO32− (3.6mlh−1g−1). Improved photoactivity may be interpreted in terms of flat band potential and electronegativity. The presence of cobalt contributes to increase the electron affinity, a desirable property for p-type specimen. It has been observed that the amount of evolved H2 rose using stronger reductors by increasing the band bending. The initial performance of catalyst was almost restored using a fresh reactant solution. With time, the water reduction slowed down because the end products Sn2- and S2O62− compete with the adsorbed water for the photoelectrons.

Keywords: Hydrogen; Spinel; p-type semi conductor; Sulfide; Polaron hopping (search for similar items in EconPapers)
Date: 2006
References: View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:31:y:2006:i:14:p:2245-2256

DOI: 10.1016/j.renene.2005.10.014

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