Photocatalytic hydrogen generation in the presence of ethanolamines over Pt/ZnIn2S4 under visible light irradiation

Using ethanolamine (EA), diethanolamine (di-EA) and triethanolamine (tri-EA) as electron donors, the photocatalytic hydrogen evolution and decomposition of the electron donors (pollutants) over Pt/ZnIn2S4 have been investigated. The Pt was deposited on ZnIn2S4 by in situ photoreduction. The three ethanolamines improve notably photocatalytic hydrogen generation with their simultaneous degradation, and their activity order for hydrogen evolution is tri-EA ≫ di-EA > EA. The adsorption of these donors on ZnIn2S4 was monitored by in situ attenuated total reflection infrared spectroscopy (ATRIR). The order of their adsorption intensity is EA > di-EA ≫ tri-EA. The activity order depends on their molecular structure and adsorption performance. The effect of concentration of the pollutants on the hydrogen generation rate is consistent with a Langmuir–Hinshelwood kinetic model. The weak basic condition is favorable for the photocatalytic hydrogen generation. A possible reaction mechanism was discussed.

The intensity order of adsorbed electron donors at ZnIn2S4 is ethanolamine (EA) > diethanolamine (di-EA) ≫ triethanolamine (tri-EA), whereas the activity order for hydrogen evolution over Pt/ZnIn2S4 is tri-EA ≫ di-EA > EA. The activity order depends on their molecular structure and adsorption performance.Figure optionsDownload high-quality image (92 K)Download as PowerPoint slideHighlights
► ZnIn2S4 as photocatalyst and ethanolamines as electron donors.
► The ethanolamines improve notably photocatalytic H2 evolution.
► The activity order for H2 evolution is tertiary > secondary > primary amine.
► The adsorption order at ZnIn2S4 is primary amine > secondary > tertiary amine.
► A possible reaction mechanism was discussed.