Clay-assisted photoproduction of hydrogen

The pH 7.0 solutions of Methyl Viologen dichloride (MV), tris (2,2′-bipyridyl) ruthenium (II) dichloride (Ru(bpy)2+3Cl2) and triethanolamine acting as a sacrificial donor, produce hydrogen when irradiated by visible light (≥395 nm) in the presence of montmorillonite or hectorite. X-ray, competitive adsorption, and luminescence results all converge to the following description of the MV2+/Ru(bpy)2+3/clay system: segregation of strained MV2+ and Ru(bpy)2+3 in the interlayer spaces of the colloidal clay suspensions, and competition between the two dications for the occupancy of the external surface sites. This model accounts for the maximum of hydrogen production obtained for a particular ratio [MV2+]/[Clay] and for the fact that pre-exchanged MV2+-Clay is unable to assist in the hydrogen photoproduction. The role of the clay in the hydrogen photoproduction process is discussed.