40 research outputs found
Hydrogen evolution at polarised liquid/liquid interfaces catalyzed by molybdenum disulfide
Molybdenum disulfide microparticles in suspension in an aqueous acidic solution adsorb at the interface with an organic electrolyte solution containing the reducing agent, decamethylferrocene, to catalyse hydrogen evolution. This catalytic process has been investigated by voltammetry at the water/1,2-dichloroethane interface and by biphasic reactions monitored by gas chromatography and UV-visible spectroscopy
Hydrogen evolution catalyzed by electrodeposited nanoparticles at the liquid/liquid interface
Aqueous protons reduction by decamethylferrocene in 1,2-dichloroethane can be catalyzed efficiently by platinum and palladium nanoparticles electrogenerated in situ at the liquid–liquid interface
Hydrogen Evolution at Liquid–Liquid Interfaces
Blowing bubbles: Hydrogen evolution by proton reduction with [(C5Me5)2Fe] occurs at a soft interface between water and 1,2-dichloroethane (DCE). The reaction proceeds by proton transfer assisted by [(C5Me5)2Fe] across the water–DCE interface with subsequent proton reduction in DCE. The interface essentially acts as a proton pump, allowing hydrogen evolution by directly using the aqueous proton
Oxygen reduction by decamethylferrocene at liquid/liquid interfaces catalyzed by dodecylaniline
Molecular oxygen (O2) reduction by decamethylferrocene (DMFc) was investigated at a polarized water/ 1,2-dichloroethane (DCE) interface. Electrochemical results point to a mechanism similar to the EC type reaction at the conventional electrode/solution interface, in which an assisted proton transfer (APT) by DMFc across the water/DCE interface via the formation of DMFcH+ corresponds to the electrochemical step and O2 reduction to hydrogen peroxide (H2O2) represents the chemical step. The proton transfer step can also be driven using lipophilic bases such as 4-dodecylaniline. Finally, voltammetric data shows that lipophilic DMFc can also be extracted to the aqueous acidic phase to react homogeneously with oxygen
Oxygen and proton reduction by decamethylferrocene in non-aqueous acidic media
Experimental studies and density functional theory (DFT) computations suggest that oxygen and proton reduction by decamethylferrocene (DMFc) in 1,2-dichloroethane involves protonated DMFc, DMFcH+, as an active intermediate species, producing hydrogen peroxide and hydrogen in aerobic and anaerobic conditions, respectively
Biphasic water splitting by osmocene
The photochemical reactivity of osmocene in a biphasic water-organic solvent system has been investigated to probe its water splitting properties. The photoreduction of aqueous protons to hydrogen under anaerobic conditions induced by osmocene dissolved in 1,2-dichloroethane and the subsequent water splitting by the osmocenium metal-metal dimer formed during H-2 production were studied by electrochemical methods, UV-visible spectrometry, gas chromatography, and nuclear magnetic resonance spectroscopy. Density functional theory computations were used to validate the reaction pathways
Molecular Electrocatalysis for Oxygen Reduction by Cobalt Porphyrins Adsorbed at Liquid/Liquid Interfaces
Molecular electrocatalysis for oxygen reduction at a polarized water/1,2-dichloroethane (DCE) interface was studied, involving aqueous protons, ferrocene (Fc) in DCE and amphiphilic cobalt porphyrin catalysts adsorbed at the interface. The catalyst, (2,8,13,17-tetraethyl-3,7,12,18-tetramethyl-5-p-aminophenylporphyrin) cobalt(II) (CoAP), functions like conventional cobalt porphyrins, activating 02 via coordination by the formation of a superoxide structure. Furthermore, due to the hydrophilic nature of the aminophenyl group, CoAP has a strong affinity for the water/DCE interface as evidenced by lipophilicity mapping calculations and surface tension measurements, facilitating the protonation of the CoAP-O-2 complex and its reduction by ferrocene. The reaction is electrocatalytic as its rate depends on the applied Galvani potential difference between the two phases
Artificial Photosynthesis at Soft Interfaces
The concept of artificial photosynthesis at a polarised liquid membrane is presented. It includes two photosystems, one at each interface for the hydrogen and oxygen evolution respectively. Both reactions involve proton coupled electron transfer reactions, and some ultrafast steps at the photosensitization stage
Oxygen reduction catalyzed by a fluorinated tetraphenylporphyrin free base at liquid/liquid interfaces
The diprotonated form of a fluorinated free base porphyrin, namely 5-(p-aminophenyl)-10,15,20-tris(pentafluorophenyl)porphyrin (H(2)FAP), can catalyze the reduction of oxygen by a weak electron donor, namely ferrocene (Fc). At a water/1,2-dichloroethane interface, the interfacial formation of H(4)FAP(2+) is observed by UV-vis spectroscopy and ion-transfer voltammetry, due to the double protonation of H(2)FAP at the imino nitrogen atoms in the tetrapyrrole ring. H(4)FAP(2+) is shown to bind oxygen, and the complex in the organic phase can easily be reduced by Fc to produce hydrogen peroxide as studied by two-phase reactions with the Galvani potential difference between the two phases being controlled by the partition of a common ion. Spectrophotometric measurements performed in 1,2-dichloroethane solutions clearly evidence that reduction of oxygen by Fc catalyzed by H(4)FAP(2+) only occurs in the presence of the tetrakis(pentafluorophenyl)borate (TB-) counteranion in the organic phase. Finally, ab initio computations support the catalytic activation of H(4)FAP(2+) on oxygen