CLAY-ASSISTED PHOTOPRODUCTION OF HYDROGEN.

The pH 7. 0 solutions of methyl viologen dichloride (MV), tris (2,2 prime -bipyridyl) ruthenium (II) dichloride (Ru(bpy)**2//3** plus Cl//2) and triethanolamine acting as a sacrificial donor, produce hydrogen when irradiated by visible light ( greater than equivalent to 395 nm) in the presence of montmorillonite or hectorite. X-ray, competitive adsorption, and luminescence results all converge to the following description of the MV**2** plus /Ru(bpy)**2//3** plus /clay system: segregation of strained MV**2** plus and Ru(bpy)**2//3** plus in the interlayer spaces of the collodial clay suspensions, and competition for the occupancy of the external surface sites. This model accounts for the maximum of hydrogen production obtained for a particular ratio left bracket MV**2** plus right bracket / left bracket Clay right bracket and for the fact that pre-exchanged MV**2** plus -Clay is unable to assist in the hydrogen photoproduction. The role of the clay in the hydrogen photoproduction process is discussed.