A Molecular Water-Reduction Catalyst: Surface Derivatization of TiO2 Colloids and Suspensions with a Platinum Complex

Roger Palmans; Arthur J. Frank

doi:10.1021/j100176a075

A Molecular Water-Reduction Catalyst: Surface Derivatization of TiO2 Colloids and Suspensions with a Platinum Complex

Roger Palmans, Arthur J. Frank

Chemistry and Nanoscience

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Abstract

Room-temperature irradiation of alkaline solutions (pH > 8) of [Pt(bpy)₂]²⁺ (where bpy is 2,2′-bipyridine) in the presence of TiO₂-SiO₂ (or TiO₂) colloids or TiO₂ powder suspensions and an electron donor results in the loss of one bipyridyl ligand and the chemical fixation of Pt(bpy) to the TiO₂ surface via the formation of Ti-O-Pt bonds. The chemical derivatization of TiO₂ with Pt(bpy) is pH dependent and proceeds through a Ti-O-Pt(bpy)₂ intermediary. X-ray photoelectron spectroscopy analysis indicates that the heterometallic surface complex Ti-O-Pt(bpy) exists in the Pt(0) and Pt(I) oxidation state. The surface complex exhibits a metal-to-ligand charge-transfer absorption band in the visible region of the spectrum. Direct excitation of either the semiconductor or the photosensitizer [Ru(bpy)₃]²⁺, electrostatically adsorbed to colloidal SiO₂-TiO₂, initiates both the surface derivatization of TiO₂ and the subsequent generation of H₂. Large turnover numbers (H₂ concentration/[Pt(bpy)₂]²⁺ ≫ 1) are observed, indicating that the Pt(bpy) species on the TiO₂ surface is catalytic and is therefore regenerated during the photoreduction of water. The rates of H₂ evolution with Pt(bpy)-TiO₂ particles are higher in acidic than basic media. The photocatalytic activity of these particles for H₂ production compares favorably with that of other TiO₂ systems charged with an equivalent Pt loading.

Original language	American English
Pages (from-to)	9438-9443
Number of pages	6
Journal	Journal of Physical Chemistry
Volume	95
Issue number	23
DOIs	https://doi.org/10.1021/j100176a075 https://doi.org/10.1021/j100176a075
State	Published - 1991

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ACNR/JA-233-12708

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@article{94ff848264c94fb1b2d9006eb20f475e,

title = "A Molecular Water-Reduction Catalyst: Surface Derivatization of TiO2 Colloids and Suspensions with a Platinum Complex",

abstract = "Room-temperature irradiation of alkaline solutions (pH > 8) of [Pt(bpy)2]2+ (where bpy is 2,2′-bipyridine) in the presence of TiO2-SiO2 (or TiO2) colloids or TiO2 powder suspensions and an electron donor results in the loss of one bipyridyl ligand and the chemical fixation of Pt(bpy) to the TiO2 surface via the formation of Ti-O-Pt bonds. The chemical derivatization of TiO2 with Pt(bpy) is pH dependent and proceeds through a Ti-O-Pt(bpy)2 intermediary. X-ray photoelectron spectroscopy analysis indicates that the heterometallic surface complex Ti-O-Pt(bpy) exists in the Pt(0) and Pt(I) oxidation state. The surface complex exhibits a metal-to-ligand charge-transfer absorption band in the visible region of the spectrum. Direct excitation of either the semiconductor or the photosensitizer [Ru(bpy)3]2+, electrostatically adsorbed to colloidal SiO2-TiO2, initiates both the surface derivatization of TiO2 and the subsequent generation of H2. Large turnover numbers (H2 concentration/[Pt(bpy)2]2+ ≫ 1) are observed, indicating that the Pt(bpy) species on the TiO2 surface is catalytic and is therefore regenerated during the photoreduction of water. The rates of H2 evolution with Pt(bpy)-TiO2 particles are higher in acidic than basic media. The photocatalytic activity of these particles for H2 production compares favorably with that of other TiO2 systems charged with an equivalent Pt loading.",

author = "Roger Palmans and Frank, {Arthur J.}",

year = "1991",

doi = "10.1021/j100176a075",

language = "American English",

volume = "95",

pages = "9438--9443",

journal = "Journal of Physical Chemistry",

issn = "0022-3654",

publisher = "American Chemical Society",

number = "23",

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T1 - A Molecular Water-Reduction Catalyst: Surface Derivatization of TiO2 Colloids and Suspensions with a Platinum Complex

AU - Palmans, Roger

AU - Frank, Arthur J.

PY - 1991

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N2 - Room-temperature irradiation of alkaline solutions (pH > 8) of [Pt(bpy)2]2+ (where bpy is 2,2′-bipyridine) in the presence of TiO2-SiO2 (or TiO2) colloids or TiO2 powder suspensions and an electron donor results in the loss of one bipyridyl ligand and the chemical fixation of Pt(bpy) to the TiO2 surface via the formation of Ti-O-Pt bonds. The chemical derivatization of TiO2 with Pt(bpy) is pH dependent and proceeds through a Ti-O-Pt(bpy)2 intermediary. X-ray photoelectron spectroscopy analysis indicates that the heterometallic surface complex Ti-O-Pt(bpy) exists in the Pt(0) and Pt(I) oxidation state. The surface complex exhibits a metal-to-ligand charge-transfer absorption band in the visible region of the spectrum. Direct excitation of either the semiconductor or the photosensitizer [Ru(bpy)3]2+, electrostatically adsorbed to colloidal SiO2-TiO2, initiates both the surface derivatization of TiO2 and the subsequent generation of H2. Large turnover numbers (H2 concentration/[Pt(bpy)2]2+ ≫ 1) are observed, indicating that the Pt(bpy) species on the TiO2 surface is catalytic and is therefore regenerated during the photoreduction of water. The rates of H2 evolution with Pt(bpy)-TiO2 particles are higher in acidic than basic media. The photocatalytic activity of these particles for H2 production compares favorably with that of other TiO2 systems charged with an equivalent Pt loading.

AB - Room-temperature irradiation of alkaline solutions (pH > 8) of [Pt(bpy)2]2+ (where bpy is 2,2′-bipyridine) in the presence of TiO2-SiO2 (or TiO2) colloids or TiO2 powder suspensions and an electron donor results in the loss of one bipyridyl ligand and the chemical fixation of Pt(bpy) to the TiO2 surface via the formation of Ti-O-Pt bonds. The chemical derivatization of TiO2 with Pt(bpy) is pH dependent and proceeds through a Ti-O-Pt(bpy)2 intermediary. X-ray photoelectron spectroscopy analysis indicates that the heterometallic surface complex Ti-O-Pt(bpy) exists in the Pt(0) and Pt(I) oxidation state. The surface complex exhibits a metal-to-ligand charge-transfer absorption band in the visible region of the spectrum. Direct excitation of either the semiconductor or the photosensitizer [Ru(bpy)3]2+, electrostatically adsorbed to colloidal SiO2-TiO2, initiates both the surface derivatization of TiO2 and the subsequent generation of H2. Large turnover numbers (H2 concentration/[Pt(bpy)2]2+ ≫ 1) are observed, indicating that the Pt(bpy) species on the TiO2 surface is catalytic and is therefore regenerated during the photoreduction of water. The rates of H2 evolution with Pt(bpy)-TiO2 particles are higher in acidic than basic media. The photocatalytic activity of these particles for H2 production compares favorably with that of other TiO2 systems charged with an equivalent Pt loading.

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A Molecular Water-Reduction Catalyst: Surface Derivatization of TiO2 Colloids and Suspensions with a Platinum Complex

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