Ultrafine and specific catalysts affording efficient hydrogen evolution from water under visible light illumination

Brugger, Pierre Alain; Cuendet, Pierre; Gräetzel, Michael

doi:10.1021/ja00401a002

Cited by 293 publications

(113 citation statements)

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“…The particular advantage of the Zn-porphyrin (ZnP) cofactor in the context of our experiments is that it is redox-inactive in its ground state but becomes a strong reductant/oxidant on UV-visible (UV-vis) excitation (45,46). ZnP-RIDC3 was prepared in high purity according to established protocols for other cytochromes (47) and displayed the expected absorption and emission features for a ZnP species (Soret maximum at 426 nm, emission maxima at 594 and 645 nm; Fig.…”

Section: +mentioning

confidence: 99%

Exceptionally stable, redox-active supramolecular protein assemblies with emergent properties

Brodin

Carr

Sontz

et al. 2014

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

105

107

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The designed assembly of proteins into well-defined supramolecular architectures not only tests our understanding of proteinprotein interactions, but it also provides an opportunity to tailor materials with new physical and chemical properties. Previously, we described that RIDC3, a designed variant of the monomeric electron transfer protein cytochrome cb 562 , could self-assemble through Zn 2+ coordination into uniform 1D nanotubes or 2D arrays with crystalline order. Here we show that these 1D and 2D RIDC3 assemblies display very high chemical stabilities owing to their metal-mediated frameworks, maintaining their structural order in ≥90% (vol/vol) of several polar organic solvents including tetrahydrofuran (THF) and isopropanol (iPrOH). In contrast, the unassembled RIDC3 monomers denature in ∼30% THF and 50% iPrOH, indicating that metal-mediated self-assembly also leads to considerable stabilization of the individual building blocks. The 1D and 2D RIDC3 assemblies are highly thermostable as well, remaining intact at up to ∼70°C and ∼90°C, respectively. The 1D nanotubes cleanly convert into the 2D arrays on heating above 70°C, a rare example of a thermal crystalline-to-crystalline conversion in a biomolecular assembly. Finally, we demonstrate that the Zn-directed RIDC3 assemblies can be used to spatiotemporally control the templated growth of small Pt 0 nanocrystals. This emergent function is enabled by and absolutely dependent on both the supramolecular assembly of RIDC3 molecules (to form a periodically organized structural template) and their innate redox activities (to direct Pt 2+ reduction).protein self-assembly | supramolecular coordination chemistry | nanomaterials | biomaterials | inorganic nanoparticles T he enormous structural and chemical diversity of proteins makes them highly attractive building blocks for functional materials. Supramolecular protein assemblies constitute the major components of cellular machinery, and many of them [e.g., 0D ferritin (1), 1D silicatein filaments (2, 3), 2D S-layers (4)] have also found a number of applications in nano-and biotechnology (2, 4, 5). Such protein assemblies are typically highly ordered, yet they possess dynamic structures that respond to external stimuli (6). Distinctively, protein assemblies are innately functional: the individual building blocks of these assemblies often perform specific chemical functions. For instance, the monomeric components of silicatein filaments or ferritin cages each have catalytic sites that process the precursors (SiO 2 or Fe 2+ ) for the downstream biomineralization processes (1, 3). On self-assembly, these individual components can be significantly stabilized (allowing them to withstand the extracellular environment and perform their functions) (7), and their chemical function takes on an entirely different context within the supramolecular architecture (acting as the template for biomineralization in the cases of silicatein and ferritin). Thus, they display emergent properties, both structurally and functionally.Such a...

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Section: +mentioning

confidence: 99%

Exceptionally stable, redox-active supramolecular protein assemblies with emergent properties

Brodin

Carr

Sontz

et al. 2014

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

105

107

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“…The same color is also observed in the citrate-stabilized Pt sol that served as the starting material in the Pt coupling reaction (inset in Figure 3). 27 If platinum is grown on the nonfunctionalized nanosheets, this absorption is absent (spectrum B), and the material appears metallic gray instead. This behavior is due to the presence of 150 nm large Pt clusters that resemble bulk Pt metal.…”

Section: Introductionmentioning

confidence: 99%

A Building Block Approach to Photochemical Water-Splitting Catalysts Based on Layered Niobate Nanosheets

et al. 2008

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We present a modular approach to the synthesis of nanostructured catalysts for photochemical splitting of water into hydrogen and oxygen. The catalysts are built from exfoliated, semiconducting niobate nanosheets derived from the layered perovskite HCa 2 Nb 3 O 10 . The latter is a catalyst for photochemical evolution of hydrogen from water under UV irradiation. After chemical modification with 3-aminopropyltrimethoxysilane (APS), IrO 2 or Pt particles can be attached to the nanosheets to produce various two-component nanostructures that were fully characterized with transmission electron microscopy and ultraviolet and infrared spectroscopy. Cyclic voltammetry was used to determine the onset potentials for O 2 and H 2 evolution. At pH ) 14, the observed values are in the range +0.61 to +1.24 V (NHE, water oxidation) and -1.36 to -1.62 V (NHE, water reduction). Under UV irradiation, all catalysts evolve hydrogen from water without any sign of deactivation for 5 h. The highest quantum efficiency of 3.49% is observed for a structure with Pt directly grown onto the nanosheets. No O 2 is evolved, which we attribute to the adsorption of O 2 to the catalyst surface. For Pt-[HCa 2 Nb 3 O 10 ], this process starts to shut down H 2 evolution after 9 h of constant irradiation, but the activity can be restored to >60% by evacuating the catalyst dispersion and purging it with Ar. Catalysts assembled from preformed citrate-coated Pt nanoparticles are slightly less active for H 2 evolution and so are catalysts that use the linker aminoethyl-aminoundecanetrimethoxysilane (AEAUS) instead of APS. The activity of IrO 2 -APS-[Ca 2 Nb 3 O 10 ] is lowest among two component catalysts, near the activities of the pure or APSmodified nanosheets. On the basis of XPS data, IrO 2 in this catalyst undergoes photochemical reduction to Ir(0) upon UV irradiation.

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“…A variety of methods can be employed for the formation of silver nanoparticles, including electrolysis, 1 biochemical, 2 gas condensation, 3 laser ablation of a silver metal plate, 4 laser irradiation of an aqueous silver solution, 5 sol-gel techniques, 6 sonochemical deposition, 7 nanostructured templates, 8 and thermal decomposition. 9 Generally, silver nanoparticles are synthesized by the reduction of silver salts in the presence of organic stabilizers in a manner similar to the acclaimed Brust's method for the synthesis of gold nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

A Facile Preparation of Silver Nanocolloids by Hydrogen Reduction of a Silver Alkylcarbamate Complex

2009

Bulletin of the Korean Chemical Society

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Controlled reduction of silver alkylcarbamate complexes with hydrogen gas was investigated as a facile synthetic method for high concentrations of silver nanocolloids in organic solvent. Polyvinylpyrrolidone (PVP) was used to stabilize the silver colloids obtained from the chemical reduction. To determine optimum conditions for preparation of the stable and controlled silver colloids with the narrowest particle size and distribution, a large number of experiments were carried out involving variations in the concentrations of the silver 2-ethylhexylcarbamate (Ag-EHCB) complex, PVP, and 2-propanol. The initial colloid had a mean particle diameter between 5∼50 nm, as measured by transmission electron microscopy, and exhibited a sharp absorption band in the UV region with a maximum size near 420 nm. After treatment with a reducing agent, the colloids were characterized by ultraviolet-visible spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy.

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Ultrafine and specific catalysts affording efficient hydrogen evolution from water under visible light illumination

Cited by 293 publications

References 1 publication

Exceptionally stable, redox-active supramolecular protein assemblies with emergent properties

Exceptionally stable, redox-active supramolecular protein assemblies with emergent properties

A Building Block Approach to Photochemical Water-Splitting Catalysts Based on Layered Niobate Nanosheets

A Facile Preparation of Silver Nanocolloids by Hydrogen Reduction of a Silver Alkylcarbamate Complex

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