Photochemical Hydrogen Production Research Articles

Colloid-chemical properties of ruthenium dioxide in relation to catalysis of the photochemical generation of hydrogen

A colloid of RuO2, prepared by thermal decomposition of RuCl3, was characterized with respect to its colloid-chemical properties and assessed as a catalyst for photochemical production of hydrogen. The RuO2 proved to be unstable towards coagulation, even under conditions of low electrolyte concentration and in the presence of polymers. The sol manifested the same electric double layer characteristics as many other oxide dispersions. The point of zero charge (p.z.c.) in indifferent electrolyte was positioned at pH 5.75.

Method of producing metallized chloroplasts and use thereof in the photochemical production of hydrogen and oxygen

Method of producing metallized chloroplasts and use thereof in the photochemical production of hydrogen and oxygen

The mechanism of the photochemical production of hydrogen from aqueous solutions of hydridotris(triethylphosphine)platinum(II)

The photolysis of aqueous solutions of [PtH(PEt3)3]+ at pH 2–12 in the presence of SO42– with near-u.v. light produces hydrogen and [Pt(PEt3)3(H2O)]2+. In the presence of Cl–, hydrogen, [PtCl(PEt3)3]+, and [PtCl2(PEt3)2] are obtained. Variations in the amount of added chloride lead to the rate expression d(H2)/dt=a[Cl–]/(b+c[Cl–]2) which can be accommodated by the formation of intermediates, [PtH2(PEt3)3Cl]+ and [PtH2(PEt3)3Cl]Cl, the latter being present as a ‘tight’ ion pair, if loss of hydrogen only occurs from the former. The first-order dependence on light intensity is taken as evidence that the platinum(IV) dihydrides are formed by protonation of the ground state of [PtH(PEt3)3]+. A similar mechanism operates in the presence of SO42– except that photochemical hydrogen production occurs more readily from [PtH2(PEt3)3(H2O)]2+ than from [PtH2(PEt3)3(SO4)].

ChemInform Abstract: Photochemical Hydrogen Production with Platinized Suspensions of Cadmium Sulfide and Cadmium Zinc Sulfide Modified by Silver Sulfide.

AbstractAn efficient H2 production can be achieved by irradiating suspensions of platinized CdS in solutions of S2′ (as hole scavenger), but only CdS photocatalysts with very low ( 6.7 m2) or verylarge ( 100 mz/ g) specific surface areas produce H2 with a significant rate.

Photochemical hydrogen production from a water-methanol mixture with small particles of iron oxide suspensions

Photochemical hydrogen production has been detected from small particles of doped iron oxide in a methanol-water (1:1) mixture. The systems studied consisted of a pure n-type semiconductor, Fe 2−xNb xO 3 (x=0.02), a pure p-type semiconductor, La 1−xSr xFeO 3 (x=0.25), and Mg-doped α-Fe 2O 3. This system was found to be heterogeneous, consisting of both spinel and corundum phase iron oxides, and shows a much higher activity than the pure single phase systems, with either corundum (α-Fe 2O 3) or spinel (Fe 3−xMg xO y) structure. The efficiency of the reaction increased substantially when the powders were loaded with Pt. Hydrogen production from these Mg-doped iron oxides is photo-ocatalytic and occurs mainly as a result of bandgap irradiation, but also occurs with sub-bandgap illumination in small amounts. There is a linearly increasing dependence of the H 2 production with increasing light intensity.

Photochemical hydrogen production with platinized suspensions of cadmium sulfide and cadmium zinc sulfide modified by silver sulfide

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotochemical hydrogen production with platinized suspensions of cadmium sulfide and cadmium zinc sulfide modified by silver sulfideJean Francois Reber and Milos RusekCite this: J. Phys. Chem. 1986, 90, 5, 824–834Publication Date (Print):February 1, 1986Publication History Published online1 May 2002Published inissue 1 February 1986https://doi.org/10.1021/j100277a024RIGHTS & PERMISSIONSArticle Views2418Altmetric-Citations363LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts

Photochemical production of hydrogen from water

The quantum yields φ( 1 2 H 2) of hydrogen production were optimized as a function of the pH and the concentrations of the components of the Ru(bpy) 3 2+/MV 2+/edta/colloidal platinum model system (bpy ≡ 2,2′-bipyridine; MV 2+ ≡ methylviologen; edta ≡ ethylenediaminetetraacetic acid) irradiated at 453 nm. An optimum quantum yield φ( 1 2 H 2) of 0.171 ± 0.020 was found for the following optimized parameters: pH 5; [Ru(bpy) 3 2+] = 5.65 × 10 −5 M; [MV 2+] = 3 × 10 −3 M; [edta] = 0.1 M; concentration of chemically prepared colloidal platinum, 1.92 × 10 −5 M. The quantum yields of the methylviologen radical cation (MV +·) were determined under the same conditions, but without platinum, and an optimum value φ(MV +·) = 0.181 ± 0.02 was obtained. The hydrogen and MV +· yields are thus closely related throughout the MV 2+ concentration range investigated which supports the fact that colloidal platinum is operating with an efficiency close to 100%. Various types of heterogeneous catalysts (radiolytically prepared colloidal metals, metal deposited onto semiconductor powders, metal and metal oxide powders) were tested and compared under optimized experimental conditions. The relative catalytic efficiency of metal hydrosols for hydrogen production was as follows: iridium, platinum, osmium > ruthenium > rhodium > cobalt, nickel, palladium, silver, gold > copper, cadmium, lead. The highest φ( 1 2 H 2) was observed for colloidal iridium (φ( 1 2 H 2) = 0.173 ± 0.020). PtTiO 2 was found to be the most efficient of the supported metals (φ′( built1 2 H 2) = 0.160 ± 0.020). Hydrogen production from water was studied as a function of the nickel content (0.5 – 13.8 wt.%) for NiTiO 2 and an optimum yield φ′( 1 2 H 2 = 0.108 ± 0.02 was found for a nickel content of about 5 wt.%. RuO 2 and IrO 2 codeposited on zeolite gave the highest yields of the metal oxides (φ′( 1 2 H 2) = 0.102 ± 0.02). The efficiencies of low cost catalysts such as nickel powder, TiO 2, Fe 2O 3, Sm 2O 3, CeO 2, MnO 2 and ZnO were also examined.

XANTHENE DYES AS SENSITIZERS FOR THE PHOTOREDUCTION OF WATER

Abstract— Some photochemical and photophysical properties of a group of xanthene dyes have been studied in relation to their roles as sensitizers for the photoreduction of water. New spectroscopic and kinetic measurements have been carried out with these dyes. The triplet states of the dyes undergo energy‐transfer and electron‐transfer, but with rate constants differing by two orders of magnitude in favour of the former pathway. The very efficient transfer of triplet energy from a group of dyes to an acceptor molecule led to the design of a greatly improved system for the photochemical production of hydrogen.

Photochemical production of hydrogen with zinc sulfide suspensions

Hydrogen has been produced efficiently by the irradiation of suspensions of metalized ZnS powders in the presence of hole scavengers such as S/sup 2 -/ and SO/sub 3//sup 2 -/ions, mixtures of these two, or S/sup 2 -/ and hypophosphite ions. Results of investigation of the properties of active ZnS photocatalysts, the reaction parameters, and the formation of the reaction products are reported. The rate of the reaction was found to be strongly dependent on the amount of ZnS, and ZnS produced 5 times as much hydrogen as CdS.

ChemInform Abstract: PHOTOCHEMICAL HYDROGEN PRODUCTION WITH CADMIUM SULFIDE SUSPENSIONS

AbstractAktive (Solarenergie‐) Photokatalysatoren wurden durch Pt‐Abscheidung auf Mikrokristalle von CdS‐Pulver hergestellt.

Photochemical hydrogen production with cadmium sulfide suspensions

Active photocatalysts for photochemical hydrogen production have been prepared by platinum deposition on microcrystals of CdS powders. Hydrogen produced by irradiating suspensions of platinized CdS in various electrolyte solutions (S/sup 2 -/, SO/sub 3//sup 2 -/, H/sub 2/PO/sup 2 -/) has been shown to be significantly improved by photoetching the CdS microcrystals. The efficiency of hydrogen formation in solutions containing S/sup 2 -/ is low due to the formation of disulfide ions. Additional of reducing agents such as sulfite or hypophosphite ions, which efficiently suppresses disulfide formation, allows hydrogen to evolve at a surprisingly high rate. In the case of a solution containing both S/sup 2/ and SO/sub 3//sup 2 -/ ions, the formation of thiosulfate is observed with a quantum yield of 0.25. In mixtures of sulfide and hypophosphite ions, phosphite and phosphate ions are the oxidation products. Hydrogen formation occurs in solutions containing SO/sub 3//sup 2 -/ ions only when the platinized CdS particles have previously been photoetched. Concomitant to the proton reduction, SO/sub 3//sup 2 -/ ions are oxidized to sulfate and dithionate. In 12 days, 9 L of H/sub 2/ was generated by irradiating 1 g of CdS/Pt suspended in an Na/sub 2/SO/sub 3/ solution. Aftermore » this period, the efficiency of the photocatalyst dropped to about 60% of the initial rate. The reaction parameters and the formation of the oxidation products have been investigated in detail. 57 references, 10 figures, 4 tables.« less

Basic problems of photochemical and photoelectrochemical hydrogen production from water

Abstract Some basic problems of feasible photochemical and photoelectrochemical methods for hydrogen (and/or oxygen) production from water by solar energy utilization were briefly discussed. The subject of the discussion is focused on the hybrid, homogeneous and heterogeneous water splitting systems. Considering the present stage of knowledge, an attempt has been made to present the weak points with respect to their reaction mechanisms, instability based on side reactions, corrosion effects of solid components, etc. It is hoped that this treatment will contribute to the improvement of existing systems and also initiate the search for new ones. Though not one of the known photochemical and photoelectrochemical methods is presently applied on a large scale some, however, show promise of realization in the near future, e.g. the hybrid photothermal-electrochemical device, Yokohama Mark 6.

Photochemical hydrogen production from ascorbic acid catalysed by tris(2, 2′-bipyridyl)ruthenium(II) and hydridotris(triethylphosphine)palladium(II)

Download options Please wait... Article information DOI https://doi.org/10.1039/DT9840000809 Article type Paper Download Citation J. Chem. Soc., Dalton Trans., 1984, 809-813 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Photochemical hydrogen production from ascorbic acid catalysed by tris(2, 2′-bipyridyl)ruthenium(II) and hydridotris(triethylphosphine)palladium(II) J. R. Fisher and D. J. Cole-Hamilton, J. Chem. Soc., Dalton Trans., 1984, 809 DOI: 10.1039/DT9840000809 To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author John R. Fisher David J. Cole-Hamilton

Adsorption properties and stability of dihexadecyl phosphate vesicles

The adsorption of the photochemical sensitizer tris(2,2'-bipyridine)ruthenium(II) on dihexadecylphosphate vesicles has been determined as a function of the pH and ionic strength of the dispersing medium. The adsorption density is a maximum at pH 7.5 � 0.5 and with minimum ionic strength(pH adjusted by adding NaOH). The stability of the vesicles with respect to flocculation, in the presence of adsorbed sensitizer, is increased when the pH is raised from 3.3 to 7.5. The presence of an amine buffer at 5 x 10-2 at pH 7.8 reduces the adsorption density by more than 90%. The relevance of these results to the interpretation of photochemistry experiments (in conjunction with photochemical hydrogen production from water) is discussed.

Photochemical production of hydrogen from water and nucleophilic platinum metal complexes

U.v. irradiation of acidic aqueous solutions of [M(PEt3)3](M = Pt or Pd), or visible irradiation of acidic aqueous solution of [HRh(PPri3)3] produces hydrogen and [M(PEt3)3(H2O)]2+ or [HRh(PPri3)2(H2O)3]2+ respectively.

Photochemical hydrogen production using cadmium sulphide suspensions in aerated water

Suspensions of CdS particles sensitize the photoreduction of H2O by cysteine and ethylenediaminetetra-acetic acid with a quantum yield of 0·04 mol/einstein(λ= 436 nm); this yield is only marginally reduced in the presence of oxygen.

Production of hydrogen by irradiation of metal complexes in aqueous solutions

Several systems in which molecular hydrogen is produced by photoreduction of protons in aqueous solutions are discussed. One mononuclear system, IrCl 2−/3− 6, is considered in detail. Ultraviolet irradiation of concentrated HCl solutions of IrCl 3− 6 yields IrCl 2− 6 and H 2. It is proposed that the reactive excited states are protonated species such as HIrCl 2− 6 that possess Cl → Ir charge transfer character, and that the photoredox mechanism involves initial release of atomic hydrogen. Irradiation of IrCl 2− 6 in aqueous HCl solutions over a broad range of wavelengths results in the formation of IrCl 3− 6 and Cl 2. Aqueous HCl is converted to hydrogen and chlorine by coupling the two photoreactions. The possible advantages of using metal cluster complexes to facilitate photochemical hydrogen production are outlined, and related experiments on Mo 2X 4− 8 (X = Cl, Br) and Rh 4b 6+ 8 ( b = 1,3-diisocyanopropane) are reviewed. Recent experiments have shown that Mo 6Cl 2− 14possesses a long-lived excited state (180 μs in CH 3CN; 2eV) that undergoes electron transfer reactions in solutions, and possible extensions of this work aimed at photoreduction of protons are considered.

ChemInform Abstract: X‐RAY STRUCTURAL ANALYSIS OF H3(RH4(BRIDGE)8CL)(COCL4)4.NH2O. THE PHOTOACTIVE SPECIES IN THE PRODUCTION OF HYDROGEN FROM AQUEOUS SOLUTIONS

The photoactive species involved in the photochemical hydrogen production in the Rh/sub 2/(bridge)/sub 4//sup 2 +/ (where (bridge) = 1,3-diisocyanopropane) system has not been previously characterized. Now, however, x-ray crystallographic data for the salt obtained on addition of CoCl/sub 2/.6H/sub 2/O to the photoactive solution of Rh/sub 2/(bridge)/sub 4/(BF/sub 4/)/sub 2/ in 12M HC1 may have elucidated the species form. It is believed that the photoactive species differs from the cation ((RH/sub 4/(bridge)/sub 8/Cl)/sup 5 +/) only by the binding of an additional Cl/sup -/ion. The crystal structure and bond distances are discussed in some detail, and it is concluded that the formula for the crystalline salt must be H/sub 3/(Rh/sub 4/(bridge)/sub 8/Cl)(CoCl/sub 4/)/sub 4/.nH/sub 2/O where n is at least 3 and more likely 6. (BLM)

Photochemical conversion and storage of solar energy

The possibilities for the photochemical storage of solar energy are examined from the standpoint of maximum efficiency and mechanism. Loss factors are considered for a general endergonic photochemical reaction and it is concluded that a realistic maximum solar energy storage efficiency for any photochemical system is 15–16%. The natural process of photochemical solar energy storage, namely, photosynthesis, is analyzed and it is found that the maximum solar energy storage efficiency of photosynthesis is 9.5 ± 0.8%. Kinetic and thermodynamic limitations on a photochemical energy storage process are identified and it is shown that the desirable production of hydrogen and oxygen from water probably cannot be sensitized with visible light if only one photochemical step is employed. However, by analogy with the mechanism of photosynthesis, two photochemical reactions operating in series permit a full utilization of the photochemically active part of the solar spectrum. A possible scheme is described and analyzed as to its possibilities and potential difficulties. Finally, some practical considerations are presented not only for the photochemical production of hydrogen but also for solid state photovoltaic devices.

Photochemical production of hot hydrogen and deuterium atoms. Reactions with hydrogen halides and halogens

Photochemical production of hot hydrogen and deuterium atoms. Reactions with hydrogen halides and halogens