Quantum confinement controlled photocatalytic water splitting by suspended CdSe nanocrystals

Holmes, Michael A.; Townsend, Troy K.; Osterloh, Frank E.

doi:10.1039/c1cc16082f

Cited by 201 publications

(134 citation statements)

References 20 publications

(21 reference statements)

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“…To evaluate the role of surface passivating ligands on photocatalytic activity, we utilized 1.8 nm diameter CuInSe 2 NCs with different PEG ligands (See Figure 7C), and finally we compared the experimental data with OLA-coated CuInSe 2 NCs under identical reaction conditions. stretched length of PEG 6 -and PEG 18 -thiolate is ~2.2 and 6.2 nm, respectively. Therefore, a 4.4 nm difference in chain length resulted in ~10% decrease in the degradation efficiency.…”

Section: Effect Of Surface Ligand Chemistry On Photocatalytic Propertmentioning

confidence: 99%

“…15 However, its large band gap (~3.4 eV) allows only ultraviolet light absorption, which hinders its potential photocatalytic applications and commercialization. The size dependency of photocatalytic solar hydrogen production 16,17 and water splitting 2,18 were investigated using suspended CdE (E = S and Se) quantum dots (QDs) as a model system, but Cd cytotoxicity hinders their use in future applications. In addition, quantitative information about (1) energy levels of the highest occupied (HOMO) and lowest unoccupied (LUMO) molecular orbitals and (2) coulombic interaction energy of photogenerated electron hole-pair (J e/h ) in NCs are extremely important to facilitate interfacial (e.g., solid-liquid) charge transfer to prepare unique nanomaterials with advanced photocatalytic activities.…”

Section: Introductionmentioning

confidence: 99%

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Investigating the Control by Quantum Confinement and Surface Ligand Coating of Photocatalytic Efficiency in Chalcopyrite Copper Indium Diselenide Nanocrystals

et al. 2016

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ABSTRACT:In the past few years, there has been an immense interest in the preparation of sustainable photocatalysts composed of semiconductor nanocrystals (NCs) as one of their component. We report here, for the first time, the effects of structural parameters of copper indium diselenide (CuInSe 2 ) NCs on visible light driven photocatalytic degradation of pollutants under homogeneous conditions. Ligand exchange reactions were performed replacing insulating, oleylamine capping with poly(ethylene glycol) thiols to prepare PEG-thiolate-capped, 1.8 to 5.3 nm diameter CuInSe 2 NCs to enhance their solubility in water. This unique solubility property caused inner-sphere electron transfer reactions (O 2 to O 2 −) to occur at the NCs surface allowing for sustainable photocatalytic reactions. Electrochemical characterization of our dissolved CuInSe 2 NCs showed that the thermodynamic driving force (-ΔG) for oxygen reduction, which increased with decreased NCs size, was the dominant contributor to the overall process when compared to the contribution light absorption and the coulombic interaction energies of electronhole pair (J e/h ). A two-fold increase in phenol degradation efficiency (from 30 to ~60%) was achieved by controlled variation of the diameter of CuInSe 2 NCs from 5.3 to 1.8 nm. The surface ligand dependency of photocatalytic efficiency was also investigated and a profound effect on phenol degradation was observed. Our PEG-thiolate-capped CuInSe 2 NCs showed photocatalytic activity towards other organic compounds, such as N, N-dimethyl-4-phenylenediamine, methylene blue, and thiourea, which showed decomposition under visible light.3

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Section: Effect Of Surface Ligand Chemistry On Photocatalytic Propertmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigating the Control by Quantum Confinement and Surface Ligand Coating of Photocatalytic Efficiency in Chalcopyrite Copper Indium Diselenide Nanocrystals

et al. 2016

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“…In this way, NCs can offer unique size-dependent optical properties and stronger light absorption over a wider spectral range than do molecular PSs (68,76). In fact, NCs as light absorbers in combination with precious metal proton reduction catalysts or with Fe-Fe hydrogenase have been studied, yielding interesting photocatalytic systems (77)(78)(79)(80)(81).…”

Section: Significancementioning

confidence: 99%

Photogeneration of hydrogen from water using CdSe nanocrystals demonstrating the importance of surface exchange

Das

Han

Haghighi

et al. 2013

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

129

139

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Unique tripodal S-donor capping agents with an attached carboxylate are found to bind tightly to the surface of CdSe nanocrystals (NCs), making the latter water soluble. Unlike that in similarly solubilized CdSe NCs with one-sulfur or two-sulfur capping agents, dissociation from the NC surface is greatly reduced. The impact of this behavior is seen in the photochemical generation of H 2 in which the CdSe NCs function as the light absorber with metal complexes in aqueous solution as the H 2 -forming catalyst and ascorbic acid as the electron donor source. This precious-metalfree system for H 2 generation from water using [Co(bdt) 2 ]− (bdt, benzene-1,2-dithiolate) as the catalyst exhibits excellent activity with a quantum yield for H 2 formation of 24% at 520 nm light and durability with >300,000 turnovers relative to catalyst in 60 h.photochemistry | solar energy | catalysis | water splitting | quantum dots A rtificial photosynthesis (AP) represents an important strategy for energy conversion from sunlight to storage in chemical bonds (1-4). Unlike natural photosynthesis in which CO 2 + H 2 O are converted into carbohydrates and O 2 , the key energy-storing reaction in AP is the splitting of water into its constituent elements of hydrogen and oxygen (5-16). As a redox reaction, water splitting can be divided into two half-reactions, of which the light-driven generation of H 2 is the reductive component. Many systems for the photogeneration of H 2 have been described over the years and they typically consist of a light absorber, a catalyst for H 2 formation, and sources of protons and electrons. For systems that function in aqueous media, the protons are provided by water, whereas for nonaqueous systems, the protons are provided by weak, generally organic acids. The source of electrons in these photochemical systems is generally a sacrificial electron donor-that is, a compound that decomposes following one electron oxidation.Reports of the light-driven generation of hydrogen date back more than 30 y, beginning with a multicomponent system containing [Ru(bpy) 3 ] 2+ (where bpy is 2,2′-bipyridine) as the chromophore or photosensitizer (PS) and colloidal Pt as the catalyst for making H 2 from protons and electrons (17). In these and many subsequent systems, electron mediators were used to accept an electron from the excited chromophore, PS*-thereby serving as an oxidative quencher-and transfer it to the catalyst. Whereas two of the initial mediators were bpy complexes of rhodium and cobalt (17, 18), the overwhelming majority of electron mediators in these systems were dialkylated 2,2′-and 4,4′-bipyridines and their derivatives (19)(20)(21)(22). The most extensively used of these mediators was methyl viologen (MV 2+ , dimethyl-4,4′-bipyridinium, usually as its chloride salt). These mediators were subsequently found to undergo deactivation in their role by hydrogenation (23, 24). The sacrificial electron donors used in these studies depended on system pH and were generally based on compounds having tertiary amine func...

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“…Orthogonalization of light absorption and carrier diffusion, [7][8][9] , quantum confinement, 10 band energetics engineering 11 and plasmonics 12,13 appear as fascinating strategies, which can be exploited to enhance the efficiencies of photoelectrochemical hydrogen generation devices. Colloidal PbS quantum dots have demonstrated to harness the infrared photons towards efficient solar hydrogen production.…”

Section: Table Of Contents (Toc)mentioning

confidence: 99%

Harnessing Infrared Photons for Photoelectrochemical Hydrogen Generation. A PbS Quantum Dot Based “Quasi-Artificial Leaf”

Trevisan

Rodenas

González-Pedro

et al. 2012

J. Phys. Chem. Lett.

102

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Hydrogen generation by using quantum dot based heterostructures has emerged as a promising strategy to develop artificial photosynthesis devices. In the present study, we sensitize mesoporous TiO 2 electrodes with in-situ deposited PbS/CdS quantum dots (QDs), aiming at harvesting light in both the visible and the near infrared for hydrogen generation. This heterostructure exhibits a remarkable photocurrent of 6 mA·cm -2 leading to 60 ml·cm -2 ·day -1 hydrogen generation. Most importantly, confirmation of the contribution of infrared photons to H 2 generation was provided by the incident-photon-to-current-efficiency (IPCE), and the integrated current was in excellent agreement with that obtained through cyclic voltammetry.The main electronic processes (accumulation, transport and recombination) were identified by impedance spectroscopy, which appears as a simple and reliable methodology to evaluate the limiting factors of these photoelectrodes. Based on this TiO 2 /PbS/CdS heterostructrure, a "quasiartificial leaf" has been developed, which has proven to produce hydrogen under simulated solar illumination at (4.30 ± 0.25) ml·cm -2 ·day -1 .

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Quantum confinement controlled photocatalytic water splitting by suspended CdSe nanocrystals

Abstract: The photocatalytic hydrogen production of CdSe nanocrystals (1.75-4.81 nm) in the presence of aqueous sodium sulphite depends exponentially on the bandgap of the particles, confirming that the material's activity is controlled by the degree of quantum confinement.

Cited by 201 publications

References 20 publications

Investigating the Control by Quantum Confinement and Surface Ligand Coating of Photocatalytic Efficiency in Chalcopyrite Copper Indium Diselenide Nanocrystals

Investigating the Control by Quantum Confinement and Surface Ligand Coating of Photocatalytic Efficiency in Chalcopyrite Copper Indium Diselenide Nanocrystals

Photogeneration of hydrogen from water using CdSe nanocrystals demonstrating the importance of surface exchange

Harnessing Infrared Photons for Photoelectrochemical Hydrogen Generation. A PbS Quantum Dot Based “Quasi-Artificial Leaf”

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