Photoelectrochemistry of molecules in zeolites and clays

Abstract

While zeolites (aluminosilicates) with supercages and window openings of molecular dimensions encapsulate molecules inside the supercages based on their size- and shape-selective properties, clays exchange cations across their aluminosilicate layers. The important aspects of the photochemistry of molecules in zeolite and clay are reduced mobility of the trapped molecules (compared with solution mobility), the stabilization of positively charged molecules and an increase in the selectivity of reactions. The present study is concerned with the absorption and emission spectral properties of tris(2,2′-bipyridine)ruthenium(II) in zeolite and clay. The nature of zeolite or clay does not appear to influence the spectral properties of molecules in these organized assemblies. The ruthenium(II) encapsulated into the supercages of zeolite-Y is electroinactive and cannot be used for photoelectrocatalytic applications. However, the sensitizer molecules incorporated into clay coated electrodes are electroactive and are capable of carrying out multi-step one-electron transfer photoelectrocatalytic reduction of oxygen to hydrogen peroxide.