Intercalation of Pt(II) Terpyridine Complexes into Layered K4Nb6O17 and Visible-Light-Driven Photocatalytic Production of H2

Direct intercalation of a [Pt(tpy)Cl]Cl (tpy: terpyridine) complex into a layered niobate (K4Nb6O17) has been successfully accomplished with the aim of developing a recyclable photocatalyst. Pt L-III-edge X-ray absorption fine structure measurement suggests that the Pt complex is intercalated into the interlayer space accompanied with ligand exchange of a Pt-Cl bond. Unlike the free Pt complex in solution, the intercalated Pt complex exhibits photoluminescence emission at room temperature due to a metal-metal-to-ligand charge-transfer ((MMLCT)-M-3) transition near 630 nm, originating from short Pt center dot center dot center dot Pt interactions (<3.5 angstrom). Such intercalated Pt complexes, which are in close proximity to each other, behave as a single-component bifunctional catalyst, enabling both visible light sensitization and H-2 production in aqueous media consisting of a sacrificial electron donor (EDTA). The turnover number based on Pt is in good accordance with the increasing intensity of luminescence emission due to the (MMLCT)-M-3 states. Moreover, leaching and agglomeration of the active Pt species is not observed, and the recovered photocatalyst can be recycled without deterioration in its catalytic activity.