Self-Assembled 8-Ti-Containing Polyoxomolybdate for the Photocatalytic Hydrogen Evolution

An S-shaped 8-Ti-containing polyoxomolybdate (NH4)Cs2Na6H3[Ti-8(GeMo9O34)(2)(GeMo5O23)(2)]<middle dot>44H(2)O (1) has been prepared under the one-pot hydrothermal method and further characterized. According to single-crystal X-ray, compound 1 consists of two {GeMo9O34} and two {GeMo5O23} segments, which are linked with a {Ti8O34} cluster. Moreover, the {GeMo5O23} fragment is rare and the first discovery, which enriches the lacunary Keggin-type family and offers the possibility of obtaining new structures. Among all of the reported polyoxomolybdates, compound 1 has the highest nuclearity of Ti centers. From the photocatalytic hydrogen evolution studies, compound 1 can be used as the heterogeneous catalyst with an H-2 evolution rate of 2392.6 mu mol g(-1) h(-1) under minimally optimized conditions.