Homogeneous catalysis of platinum blue related complexes in photoreduction of water into hydrogen

Abstract

Evolution of H 2 by simple dissolution of either [Pt 2(NH 3) 4(C 4H 6NO) 2] 2-(PF 6) 4, [Pt 4(NH 3) 8(C 4H 6NO) 4](NO 3) 2(PF 6) 3·5H 2O or [Pt 4(NH 3) 8(C 4H 6NO) 4]-(NO 3) 6·2H 2O (C 4H 6NO is deprotonated α-pyrrolidone) into water, without light irradiation, is observed by gas chromatography. The H 2 evolution seems to be due to an interaction between [Pt 4(NH 3) 8(C 4H 6NO) 4] 6+ and proton, which is confirmed by UV-visible spectrophotometry. An attempt is made to utilize the reaction in the photochemical reduction of water into hydrogen. [Pt 4(NH 3) 8(C 4H 6NO) 4] 6+ and [Pt 4(NH 3) 8(C 5H 4NO) 4] 5+ are used as homogeneous hydrogen-producing catalysts in a photochemical model system containing EDTA as sacrificial electron donor, Ru(bpy) 3 2+ as a photosensitizer and methyl-viologen (MV 2+) as an electron relay. Quantum yields for their hydrogen productions are calculated to be 0.022 and 0.11, respectively.