Structural aspects in the photooxidation and photoreduction of water in clay mineral suspensions

Abstract

The photosensitized cleavage of water is hampered by fast recombination of usually charged intermediates. Charged surfaces carrying the appropriate catalyst for both the oxidation and reduction of the substrate might be used to compete with this recombination. In this study negatively charged clay minerals and positively charged Al(OH)x gels were examined as catalyst supports capable of exerting such electrostatic interactions. Eu3+ cations were used as quenchers of the excited state of the photosensitizer and vectors of the absorbed energy. It is shown that electrostatic effects do play a role in such systems, and that the tridimensional structure of the catalyst supports must be taken into account when designing a heterogeneous photocatalytic water cleavage system.