Photocatalytic Generation of Hydrogen from Water Using a Platinum(II) Terpyridyl Acetylide Chromophore

Abstract

The cationic complex [Pt(tolylterpyridine)(phenylacetylide)]⁺ has been used as a photosensitizer for the reduction of aqueous protons in the presence of a sacrificial electron donor to make H₂. In this system, triethanolamine (TEOA) acts as the sacrificial reducing agent, methyl viologen (MV²⁺) serves as an electron transfer agent, and colloidal Pt stabilized by polyacrylate functions as the catalyst for H₂ generation. The Pt(II) chromophore undergoes both oxidative and reductive quenching, but H₂ is only seen when both TEOA and MV²⁺ are present. Irradiation of the reaction solution for 10 h with λ > 410 nm leads to 85 turnovers and an overall yield of 34% based on TEOA. While H₂ evolution is maximized for the system at pH 7, it is also seen at pH 5 and 9, in contrast with earlier reports using Ru(bpy)₃²⁺ as the photosensitizer. This is the first time that a Pt diimine or terpyridyl complex has been used as the photosensitizer for H₂ generation from aqueous protons.