Electrochemically decoupled reduction of CO to formate over a dispersed heterogeneous bismuth catalyst enabled redox mediators.

Electrochemical CO reduction is a topic of major interest in contemporary research as an approach to use renewably-derived electricity to synthesise useful hydrocarbons from waste CO. Various strategies have been developed to optimise this challenging reaction at electrode interfaces, but to-date, decoupled electrolysis has not been demonstrated for the reduction of CO. Decoupled electrolysis aims to use electrochemically-derived charged redox mediators - electrical charge and potential vectors - to separate catalytic product formation from the electrode surface.

Exploring the Electrochemistry of Iron Dithiolene and Its Potential for Electrochemical Homogeneous Carbon Dioxide Reduction.

In this work, the dithiolene complex iron(III) bis-maleonitriledithiolene [Fe(mnt)] is characterised and evaluated as a homogeneous CO reduction catalyst. Electrochemically the Fe(mnt) is reduced twice to the trianionic Fe(mnt) state, which is correspondingly found to be active towards CO. Interestingly, the first reduction event appears to comprise overlapping reversible couples, attributed to the presence of both a dimeric and monomeric form of the dithiolene complex.

Dithiolene Complexes of First-Row Transition Metals for Symmetric Nonaqueous Redox Flow Batteries.

Five metal complexes of the dithiolene ligand maleonitriledithiolate (mnt ) with M=V, Fe, Co, Ni, Cu were studied as redox-active materials for nonaqueous redox flow batteries (RFBs). All five complexes exhibit at least two redox processes, making them applicable to symmetric RFBs as single-species electrolytes, that is, as both negolyte and posolyte. Charge-discharge cycling in a small-scale RFB gave modest performances for [(tea) V ], [(tea) Co ], and [(tea) Cu ] whereas [(tea)Fe ] and [(tea) Ni ] (tea=tetraethylammonium) failed to hold any significant capacity, indicating poor stability.

Redox Flow Batteries, Hydrogen and Distributed Storage.

Social, economic, and political pressures are causing a shift in the global energy mix, with a preference toward renewable energy sources. In order to realize widespread implementation of these resources, large-scale storage of renewable energy is needed. Among the proposed energy storage technologies, redox flow batteries offer many unique advantages.

Photoreduction of CO2 using [Ru(bpy)2(CO)L]n+ catalysts in biphasic solution/supercritical CO2 systems.

The reduction of CO2 in a biphasic liquid-condensed gas system was investigated as a function of the CO2 pressure. Using 1-benzyl-1,4-dihydronicotinamide (BNAH) as sacrificial electron donor dissolved in a dimethylformamide-water mixture and [Ru(bpy)2(CO)L](n+) as a catalyst and [Ru(bpy)3](2+) as a photosensitizer, the reaction was found to produce a mixture of CO and formate, in total about 250 μmol after just 2 h. As CO2 pressure increases, CO formation is greatly favored, being four times greater than that of formate in aqueous systems.

Steady-state macroscale voltammetry in a supercritical carbon dioxide medium.

The electrochemical oxidation and reduction of decamethylferrocene is demonstrated in supercritical carbon dioxide at a macro gold disc electrode at 100 bar and 313 K. Fast mass transport effects were exhibited and the corresponding steady-state voltammetry was observed at high scan rates. A highly lipophilic room temperature ionic liquid that readily dissolved in supercritical CO(2) with acetonitrile as a co-solvent was used as an electrolyte, allowing for a conducting supercritical single phase.