Mastering the production of solar fuels by artificial photosynthesis would be a considerable feat, either water splitting into hydrogen and oxygen or reduction CO(2) to methanol hydrocarbons: 2H(2)O + 4hnu --> O(2) 2H(2); 8hnu 2O(2) CH(4). It is notable that oxidation dioxygen key half-reaction in both. In principle, these fuel reactions can coupled light absorption molecular assemblies, nanostructured arrays, photoelectrochemical cells (PECs) modular approach. The approach uses absorption,...

Water oxidation is a key reaction in natural photosynthesis and many schemes for artificial photosynthesis. Although metal complexes capable of oxidizing water based on Ru, Mn, Ir are known, significant question whether or not dimeric higher order structures required oxidation. We report here single-site catalytic by the monomeric [Ru(tpy)(bpm)(OH2)]2+ [Ru(tpy)(bpz)(OH2)]2+ (tpy 2,2′:6′,2′′-terpyridine; bpm 2,2′-bipyrimidine; bpz 2,2′-bipyrazine) well-defined mechanism involving RuV═O.

The mechanism of Ce(IV) water oxidation catalyzed by [Ru(tpy)(bpm)(OH2)]2+ (tpy = 2,2′:6′,2′′-terpyridine; bpm 2,2′-bipyrimidine) and related single-site catalysts has been determined a combination mixing stopped-flow experiments with spectrophotometric monitoring. features O---O coupling attack on RuV═O3+ three peroxidic intermediates that have characterized spectroscopy DFT calculations.

The blue dimer, cis,cis-[(bpy)2(H2O)RuIIIORuIII(H2O)(bpy)2]4+, is the first designed, well-defined molecule known to function as a catalyst for water oxidation. It meets stoichiometric requirements oxidation, 2H2O → −4 e − ,−4 H + O−O, by utilizing proton-coupled electron-transfer (PCET) reactions in which both electrons and protons are transferred. This avoids charge buildup, allowing accumulation of multiple oxidative equivalents at Ru−O−Ru core. PCET pathways involving coupled...

In the early 1970s, works by Fujishima and Honda (1) et al. (2) reported on results of a now famous experiment. They showed that band gap excitation anatase TiO2 in photoelectrochemical cell with Pt counter electrode an applied bias resulted water splitting into hydrogen oxygen. The timing result was impeccable. 1973, Organization Petroleum Exporting Countries (OPEC) declared embargo oil imports to West, resulting gasoline shortages long lines at gas pumps. Suddenly, there pressing need for...

As the terminal step in photosystem II, and a potential half-reaction for artificial photosynthesis, water oxidation (2H 2 O → + 4 e - 4H ) is key, but it imposes significant mechanistic challenge with requirements both /4H loss O—O bond formation. Significant progress catalysis has been achieved recently by use of single-site Ru metal complex catalysts such as [Ru(Mebimpy)(bpy)(OH )] 2+ [Mebimpy = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine; bpy 2,2 ′ -bipyridine]. When oxidized from to V 3+...

A series of monomeric ruthenium polypyridyl complexes have been synthesized and characterized, their performance as water oxidation catalysts has evaluated. The diversity ligand environments how they influence rates reaction thermodynamics create a platform for catalyst design with controllable reactivity based on variations.

Electrocatalytic reduction of CO(2) by [Ru(tpy)(bpy)(solvent)](2+) (tpy = 2,2':6',2''-terpyridine, bpy 2,2'-bipyridine) and its structural analogs is initiated sequential 1e(-) reductions at the tpy ligands followed rate limiting addition to give a metallocarboxylate intermediate. It undergoes further loss CO.

Artificial photosynthesis and the production of solar fuels could be a key element in future renewable energy economy providing solution to storage problem conversion. We describe hybrid strategy for water splitting based on dye sensitized photoelectrosynthesis cell. It uses derivatized, core-shell nanostructured photoanode with core high surface area conductive metal oxide film--indium tin or antimony oxide--coated thin outer shell TiO2 formed by atomic layer deposition. A...

Water oxidation is a key half reaction in energy conversion schemes based on solar fuels and targets such as light driven water splitting or carbon dioxide reduction into CO, other oxygenates, hydrocarbons. Carrying out these reactions at rates that exceed the rate of insolation for extended periods time required useful applications presents major challenge. “other” it dominated by PCET given its multi-electron, multi-proton character, 2H2O → O2 + 4e− 4H+. Identification was an offshoot...

Electrocatalytic water oxidation occurs through the use of phosphonate-derivatized single-site catalyst [Ru(Mebimpy)(4,4'-((HO)(2)OPCH(2))(2)bpy)(OH(2))](2+) [Mebimpy = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine; bpy 2,2'-bipyridine] at pH 1 and 5 on fluorine-doped SnO(2) or Sn(IV)-doped In(2)O(3) electrodes nanocrystalline TiO(2). The surface-bound appears to retain mechanism found for [Ru(tpy)(bpm)(OH(2))](2+) [Ru(tpy)(bpz)(OH(2))](2+) (tpy 2,2':6',2''-terpyridine; bpm 2,2'-bipyrimidine;...

The metal complex [(tpy)(Mebim-py)Ru II (S)] 2+ (tpy = 2,2 ′ : 6 ,2 ′′ -terpyridine; Mebim-py 3-methyl-1-pyridylbenzimidazol-2-ylidene; S solvent) is a robust, reactive electrocatalyst toward both water oxidation to oxygen and carbon dioxide reduction monoxide. Here we describe its use as single for CO 2 splitting, → + 1/2 O , in two-compartment electrochemical cell.

The photostability of [RuII(bpy)2(4,4′-(PO3H2)2bpy)]Cl2 (bpy = 4,4′-bipyridine) on nanocrystalline TiO2 and ZrO2 films was investigated using a standard measurement protocol. Stability evaluated by monitoring visible light absorbance spectral changes, in real time, during 455 nm photolysis (30 fwhm, 475 mW/cm2) variety conditions relevant to dye-sensitized solar cells photoelectrosynthesis cells. Desorption (kdes) photochemical (kchem) processes were observed found be dependent upon solvent,...

Alles in einem bieten die Assoziate aus "Single-Site"-Wasseroxidationskatalysatoren (rot und blau) Redoxvermittlern (grün blau), – sowohl Lösung als auch über Phosphonatlinker an Metalloxidoberflächen gebunden stabile, robuste Katalysatoren für Wasseroxidation wirken. Mehr 28 000 Umsätze wurden mit einer Ladungseffizienz >95 % Sauerstoffproduktion ohne Abnahme der katalytischen Aktivität erreicht.

The performance of dye-sensitized solar and photoelectrochemical cells is strongly dependent on the light absorption electron transfer events at semiconductor–small molecule interface. These processes as well photo/electrochemical stability are dictated not only by properties chromophore metal oxide but also structure dye molecule, number surface binding groups, their mode to surface. In this article, we report photophysical electrochemical a series six phosphonate-derivatized [Ru(bpy)3]2+...

The complex [Ru(Mebimpy)(bpy)(OH(2))](2+) [Mebimpy = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine; bpy 2,2'-bipyridine] and its 4,4'-(PO(3)H(2)CH(2))(2)bpy derivative on oxide electrodes are water oxidation catalysts in propylene carbonate 2,2,2-trifluoroethanol (TFE) to which has been added as a limiting reagent. rate of is greatly enhanced relative that with the solvent occurs by pathway first-order H(2)O; an additional acetate appears when TFE used solvent.

In aqueous solution above pH 2.4 with 4% (vol/vol) CH3CN, the complex [Ru(II)(bda)(isoq)2] (bda is 2,2'-bipyridine-6,6'-dicarboxylate; isoq isoquinoline) exists as open-arm chelate, [Ru(II)(CO2-bpy-CO2(-))(isoq)2(NCCH3)], shown by (1)H and (13)C-NMR, X-ray crystallography, titrations. Rates of water oxidation chelate are remarkably enhanced added proton acceptor bases, measured cyclic voltammetry (CV). 1.0 M PO4(3-), calculated half-time for ∼7 μs. The key to rate accelerations bases direct...

Enhancing the surface binding stability of chromophores, catalysts, and chromophore-catalyst assemblies attached to metal oxide surfaces is an important element in furthering development dye sensitized solar cells, photoelectrosynthesis interfacial molecular catalysis. Phosphonate-derivatized catalysts provide a basis for sustained water oxidation on these acidic solution but are unstable toward hydrolysis loss from as pH increased. Here, we report enhanced phosphonate-derivatized catalyst...

Simple assembly: A "layer-by-layer" deposition of functionalized dyes/catalysts on the surfaces nanocrystalline oxides is introduced. The strategy general and offers considerable flexibility based phosphonate- or carboxylate-binding groups with ZrIV as bridging ions. resulting bilayer structures are capable supporting rapid intra-layer energy electron transfer (see picture).

In order for solar energy to serve as a primary source, it must be paired with storage on massive scale. At this scale, fuels and in chemical bonds is the only practical approach. Solar are produced amounts by photosynthesis reduction of CO 2 water give carbohydrates but efficiencies low. photosystem II (PSII), oxygen-producing site photosynthesis, light absorption sensitization trigger cascade coupled electron-proton transfer events time scales ranging from picoseconds microseconds....

Photoinduced formation, separation, and buildup of multiple redox equivalents are an integral part cycles for producing solar fuels in dye-sensitized photoelectrosynthesis cells (DSPECs). Excitation wavelength-dependent electron injection, intra-assembly transfer, pH-dependent back transfer on TiO2 were investigated the molecular assembly [((PO3H2-CH2)-bpy)2Rua(bpy-NH-CO-trpy)Rub(bpy)(OH2)]4+ ([TiO2–RuaII–RubII–OH2]4+; ((PO3H2-CH2)2-bpy =...

Water-stable, surface-bound chromophores, catalysts, and assemblies are an essential element in dye-sensitized photoelectrosynthesis cells for the generation of solar fuels by water splitting CO2 reduction to CO, other oxygenates, or hydrocarbons. Phosphonic acid derivatives provide a basis stable chemical binding on metal oxide surfaces. We report here efficient synthesis 4,4'-bis(diethylphosphonomethyl)-2,2'-bipyridine 4,4'-bis(diethylphosphonate)-2,2'-bipyridine, as well mono-, bis-,...

Electrocatalytic water oxidation occurs at fluoride-doped tin oxide (FTO) electrodes that have been surface-modified by addition of Co(II). On the basis X-ray photoelectron spectroscopy and transmission electron microscopy measurements, active surface site appears to be a single or small-molecule assembly bound as Co(II), with no evidence for cobalt film cluster formation. cyclic voltammetry surface-bound Co(II) undergoes pH-dependent 1e(-)/1H(+) Co(III), which is followed catalytic...