Efficient Photocatalytic Hydrogen Evolution from Water without an Electron Mediator over Pt-Rose Bengal Catalysts

A highly efficient visible-light-induced hydrogen evolution system without an electron mediator such as methyl viologen, constructed with rose bengal as a photosensitizer, triethanolamine (TEA) as an electron donor, and Pt as a cocatalyst, has been reported. Under visible light irradiation (λ g 420 nm), the highest rate of hydrogen evolution and apparent quantum efficiency are about 56.9 μmol h-1 and 11.3%, respectively. According to the effects of urea and ionic strength on the activity of hydrogen evolution, the dimers of rose bengal play a significant role in the photosensitized hydrogen evolution process. On the basis of activity tests and UV-vis absorbance and fluorescence measurements, the probable mechanism for photosensitized hydrogen evolution has been postulated.