Redox electrocatalysis (catalysis of electron-transfer reactions by floating conductive particles) is discussed from the point-of-view of Fermi level equilibration, and an overall theoretical framework is given. Examples of redox electrocatalysis in solution, in bipolar configuration, and at liquid-liquid interfaces are provided, highlighting that bipolar and liquid-liquid interfacial systems allow the study of the electrocatalytic properties of particles without effects from the support, but only liquid-liquid interfaces allow measurement of the electrocatalytic current directly. Additionally, photoinduced redox electrocatalysis will be of interest, for example, to achieve water splitting.
The photoinduced hydrogen evolution reaction (HER) by decamethylruthenocene,C p 2 *Ru II (Cp* = C 5 Me 5 ), is reported. The use of am etallocene to photoproduce hydrogen is presented as an alternative strategy to reduce protons without involving an additional photosensitizer.T he mechanism was investigated by (spectro)electrochemical and spectroscopic (UV/Vis and 1 HNMR) measurements.T he photoactivated hydride involved was characterized spectroscopically and the resulting [Cp 2 *Ru III ] + species was electrochemically regenerated in situ on af luorinated tin oxide electrode surface.Apromising internal quantum yield of 25 %w as obtained. Optimal experimental conditionsespecially the use of weakly coordinating solvent and counterions-are discussed.Thedevelopmentofsimpleandefficientmethodstoproduce molecular hydrogen (H 2 )i st he focus of intense research. Va rious state-of-the-art multicomponent artificial photosystems for H 2 generation are currently under heavy scrutiny and generally consist of ah ighly engineered catalyst, photosensitizer,electron mediator or relay combinations, [1] and are often fueled by sacrificial electron donors (for example, triethylamine, [2] triethanolamine, [2b] benzyl-dihydronicotinamide, [3] and so forth). Thel atter irreversibly oxidizes upon charge transfer and provides protons and electrons to the catalyst. Consequently,s acrificial systems consume af uel to produce H 2 while electrochemical systems only consume electricity (that is now being increasingly produced in as ustainable manner). Indeed, the electrode can both accept and donate electrons.N oi rreversible reactions take place at this step,a nd the protons are supplied from the solution.Metallocenes appear as an attractive class of molecules capable of achieving the complex photogeneration of H 2 by themselves.Indeed, they are able to both reduce protons and undergo photoactivation. Therefore,t hese "all-in-one" molecules would offer an interesting alternative to state-ofthe-art multicomponent photosystems as fewer electron transfer steps are involved. Moreover,they are simple,easily synthesized molecules,w ith ligands and metal centers that may be tuned to obtain certain desired properties,s uch as tailored solubility,a bsorbance wavelength, or redox potentials.Recently,w ed emonstrated the possibility to produce H 2 in the dark using decamethylferrocene (Cp 2 *Fe II ;C p* = C 5 Me 5 )asanelectron donor in abiphasic system.[4] Motivated by these early findings,weset out to explore the reactivity of other metallocenes as suitable electron donors.I nterestingly, both osmocene (Cp 2 Os II ;C p = C 5 H 5 ) [5] and decamethylosmocene (Cp 2 *Os II ) [6] demonstrated the capability to produce H 2 upon light irradiation. Other works have proposed the use of asingle molecule to achieve photogeneration of H 2 . Fore xample,C ole-Hamilton [7] reported ap latinum phosphine compound, while both Miller [8] and Gray [9] used iridium chloride complexes.Herein, we report Cp 2 *Ru II as the first metallocene capable of perfo...
An innovative strategy is proposed to synthesize single‐crystal nanowires (NWs) of the Al3+ dicarboxylate MIL‐69(Al) MOF by using graphene oxide nanoscrolls as structure‐directing agents. MIL‐69(Al) NWs with an average diameter of 70±20 nm and lengths up to 2 μm were found to preferentially grow along the [001] crystallographic direction. Advanced characterization methods (electron diffraction, TEM, STEM‐HAADF, SEM, XPS) and molecular modeling revealed the mechanism of formation of MIL‐69(Al) NWs involving size‐confinement and templating effects. The formation of MIL‐69(Al) seeds and the self‐scroll of GO sheets followed by the anisotropic growth of MIL‐69(Al) crystals are mediated by specific GO sheets/MOF interactions. This study delivers an unprecedented approach to control the design of 1D MOF nanostructures and superstructures.
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