Photogeneration of Hydrogen from Water Using an Integrated System Based on TiO<sub>2</sub> and Platinum(II) Diimine Dithiolate Sensitizers

Zhang, Jie; Du, Pingwu; Schneider, Jacob; Jarosz, Paul; Eisenberg, Richard

doi:10.1021/ja071789h

Cited by 181 publications

(130 citation statements)

References 27 publications

(42 reference statements)

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“…As a consequence of the mixed character of the HOMO in PtN 2 S 2 , the excited states derived from HOMO to LUMO (lowest unoccupied molecular orbital) excitation have been labeled mixedmetal ligand-to-ligand′ charge transfers (MMLL′CT). Based on these charge transfer states, two of the PtN 2 S 2 complexes, including 1 with R = COOH, were examined as photosensitizers for H 2 generation with TiO 2 as the electron conduit and Pt islands on the TiO 2 surface as the catalyst (49). The deprotonated carboxlyate groups of di(carboxy)bipyridine (dcbpy) served to link the PS to the platinized TiO 2 (Pt-TiO 2 ).…”

Section: Significancementioning

confidence: 99%

Light-driven generation of hydrogen: New chromophore dyads for increased activity based on Bodipy dye and Pt(diimine)(dithiolate) complexes

Zheng

Sabatini

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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New dyads consisting of a strongly absorbing Bodipy (dipyrromethene-BF 2 ) dye and a platinum diimine dithiolate (PtN 2 S 2 ) charge transfer (CT) chromophore have been synthesized and studied in the context of the light-driven generation of H 2 from aqueous protons. In these dyads, the Bodipy dye is bonded directly to the benzenedithiolate ligand of the PtN 2 S 2 CT chromophore. Each of the new dyads contains either a bipyridine (bpy) or phenanthroline (phen) diimine with an attached functional group that is used for binding directly to TiO 2 nanoparticles, allowing rapid electron photoinjection into the semiconductor. The absorption spectra and cyclic voltammograms of the dyads show that the spectroscopic and electrochemical properties of the dyads are the sum of the individual chromophores (Bodipy and the PtN 2 S 2 moieties), indicating little electronic coupling between them. Connection to TiO 2 nanoparticles is carried out by sonication leading to in situ attachment to TiO 2 without prior hydrolysis of the ester linking groups to acids. For H 2 generation studies, the TiO 2 particles are platinized (Pt-TiO 2 ) so that the light absorber (the dyad), the electron conduit (TiO 2 ), and the catalyst (attached colloidal Pt) are fully integrated. It is found that upon 530 nm irradiation in a H 2 O solution (pH 4) with ascorbic acid as an electron donor, the dyad linked to Pt-TiO 2 via a phosphonate or carboxylate attachment shows excellent light-driven H 2 production with substantial longevity, in which one particular dyad [4(bpyP)] exhibits the highest activity, generating ∼40,000 turnover numbers of H 2 over 12 d (with respect to dye).photochemistry | solar energy conversion | hydrogen | spectroscopy | synthesis W ater splitting into hydrogen and oxygen is the key energystoring reaction of artificial photosynthesis (AP) and one of the most promising long-term strategies for carbon-free energy on a potentially global scale (1). As a redox reaction, water splitting has been studied primarily in terms of its two halfreactions, the reduction of aqueous protons to H 2 and the oxidation of water to O 2 (2-13). Whereas some of these studies date back more than 30 y (14-22), recent progress on each halfreaction has been notable, particularly with regard to catalyst development and mechanistic understanding of each transformation (6,(23)(24)(25)(26)(27)(28)(29). In this paper, we focus on efforts dealing with the lightdriven generation of H 2 , which in its simplest form requires a light absorber or photosensitizer (PS) for electron-hole creation, a means or pathway for charge separation and electron transfer, an aqueous proton source, a catalyst for collecting electrons and protons and promoting their conversion to H 2 , and an ultimate source of electrons in the form of an electron donor.Dating from the earliest work on the light-driven generation of H 2 , the photosensitizer has most often been a Ru(II) complex with 2,2′-bipyridine (bpy) and/or related heterocyclic ligands having a long-lived triplet metal-to-ligand ...

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Section: Significancementioning

confidence: 99%

Light-driven generation of hydrogen: New chromophore dyads for increased activity based on Bodipy dye and Pt(diimine)(dithiolate) complexes

Zheng

Sabatini

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…[1][2][3] The representative compounds include Pt II and Ir III complexes, etc. [1,4] Recently, these complexes have been found to have new applications in photocatalysis, [5] optical limiting, [6] molecular probes, [7,8] and upconversions. [9][10][11][12][13][14] Concerning these new applications, the ability to have strong visible-light harvesting and to access the long-lived triplet-excited states are often very crucial.…”

Section: Introductionmentioning

confidence: 99%

Long‐Lived Room‐Temperature Near‐IR Phosphorescence of BODIPY in a Visible‐Light‐Harvesting N^C^N Pt^II–Acetylide Complex with a Directly Metalated BODIPY Chromophore

Zhao

Guo

et al. 2012

Chemistry A European J

142

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Room-temperature long-lived near-IR phosphorescence of boron-dipyrromethene (BODIPY) was observed (λ(em) = 770 nm, Φ(P) = 3.5 %, τ(P) = 128.4 μs). Our molecular-design strategy is to attach Pt(II) coordination centers directly onto the BODIPY π-core using acetylide bonds, rather than on the periphery of the BODIPY core, thus maximizing the heavy-atom effect of Pt(II). In this case, the intersystem crossing (ISC) is facilitated and the radiative decay of the T(1) excited state of BODIPY is observed, that is, the phosphorescence of BODIPY. The complex shows strong absorption in the visible range (ε = 53,800 M(-1) cm(-1) at 574 nm), which is rare for Pt(II)-acetylide complexes. The complex is dual emissive with (3)MLCT emission at 660 nm and the (3)IL emission at 770 nm. The T(1) excited state of the complex is mainly localized on the BODIPY moiety (i.e. (3)IL state, as determined by steady-state and time-resolved spectroscopy, 77 K emission spectra, and spin-density analysis). The strong visible-light-harvesting ability and long-lived T(1) excite state of the complex were used for triplet-triplet annihilation based upconversion and an upconversion quantum yield of 5.2 % was observed. The overall upconversion capability (η = ε×Φ(UC)) of this complex is remarkable considering its strong absorption. The model complex, without the BODIPY moiety, gives no upconversion under the same experimental conditions. Our work paves the way for access to transition-metal complexes that show strong absorption of visible light and long-lived (3)IL excited states, which are important for applications in photovoltaics, photocatalysis, and upconversions, etc.

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“…The second problem stimulated a change in the Pt(II) chromophore away from acetylide complexes to corresponding dithiolate systems since these complexes were known from numerous earlier studies to have a lower energy 3 CT state involving a mixed Pt(d)/S(p)/dithiolate HOMO and a * diimine LUMO. Importantly, Pt(diimine)(dithiolate) complexes when attached to TiO 2 through carboxylate substituents on the diimine were reported by Arakawa to generate photocurrent.…”

Section: Photogeneration Ofmentioning

confidence: 99%

“…In these studies we concentrated on the use of solution luminescent Pt(II) complexes that contain a bi-or terpyridyl ligand for light absorption. These complexes, like the more extensively studied d 6 Ru(II) complexes with similar hetero-aromatic ligands, possess solution luminescent 3 MLCT excited states that can undergo electron transfer reactions.…”

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confidence: 99%

Design, Synthesis and Study of Multi-Component and Integrated Systems for Light-Driven Hydrogen Generation

Eisenberg¹

2012

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The final technical report for DE-FG02-90ER14125 (021) covers the period 2006-2009 since the grant represented a one year phase down of the project DE-FG02-90ER14125 (A020). The work during the final year involved completion and publication of studies that are listed at the end of this report. Notable progress was made over the four year period ending February 28, 2010, and the results have contributed to a greater understanding of the complexities and subtleties of this seemingly simple process. In these studies we concentrated on the use of solution luminescent Pt(II) complexes that contain a bi-or terpyridyl ligand for light absorption. These complexes, like the more extensively studied d 6 Ru(II) complexes with similar hetero-aromatic ligands, possess solution luminescent 3 MLCT excited states that can undergo electron transfer reactions.Two different lines of inquiry were followed in the research conducted during the past four years. The first deals with the photo-generation of H 2 employing a multiple component system consisting of a platinum(II) chromophore, an electron relay, a sacrificial electron source and colloidal Pt as the actual H 2 -generating catalyst, while the second concentrates on photoinduced charge separation (PICS) using a similar platinum(II) chromophore covalently connected to spatially specific electron donor and acceptor moieties. The latter has included collaborative transient absorption (TA) measurements on the ns timescale with Professor Russell Schmehl of Tulane University. Photogeneration of Hydrogen.In 2006, we reported that, like [Ru(bpy) 3 ] 2+ , complex 1 can promote the photochemical generation of H 2 in a system containing methyl viologen (MV 2+ ) as the electron relay, triethanol amine (TEOA) as the sacrificial electron donor and colloidal Pt as the H 2 -generating catalyst. The kinetic dependences of both pH and [MV 2+ ] on H 2 generation were found to be non-monotonic, suggestive of the involvement of these

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Photogeneration of Hydrogen from Water Using an Integrated System Based on TiO₂ and Platinum(II) Diimine Dithiolate Sensitizers

Cited by 181 publications

References 27 publications

Light-driven generation of hydrogen: New chromophore dyads for increased activity based on Bodipy dye and Pt(diimine)(dithiolate) complexes

Light-driven generation of hydrogen: New chromophore dyads for increased activity based on Bodipy dye and Pt(diimine)(dithiolate) complexes

Long‐Lived Room‐Temperature Near‐IR Phosphorescence of BODIPY in a Visible‐Light‐Harvesting N^C^N Pt^II–Acetylide Complex with a Directly Metalated BODIPY Chromophore

Design, Synthesis and Study of Multi-Component and Integrated Systems for Light-Driven Hydrogen Generation

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Photogeneration of Hydrogen from Water Using an Integrated System Based on TiO2 and Platinum(II) Diimine Dithiolate Sensitizers

Cited by 181 publications

References 27 publications

Light-driven generation of hydrogen: New chromophore dyads for increased activity based on Bodipy dye and Pt(diimine)(dithiolate) complexes

Light-driven generation of hydrogen: New chromophore dyads for increased activity based on Bodipy dye and Pt(diimine)(dithiolate) complexes

Long‐Lived Room‐Temperature Near‐IR Phosphorescence of BODIPY in a Visible‐Light‐Harvesting N^C^N PtII–Acetylide Complex with a Directly Metalated BODIPY Chromophore

Design, Synthesis and Study of Multi-Component and Integrated Systems for Light-Driven Hydrogen Generation

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Photogeneration of Hydrogen from Water Using an Integrated System Based on TiO₂ and Platinum(II) Diimine Dithiolate Sensitizers

Long‐Lived Room‐Temperature Near‐IR Phosphorescence of BODIPY in a Visible‐Light‐Harvesting N^C^N Pt^II–Acetylide Complex with a Directly Metalated BODIPY Chromophore