Directing the Outcome of CO Reduction at Bismuth Cathodes Using Varied Ionic Liquid Promoters.

Ionic liquids (ILs) have been established as effective promoters for the electrocatalytic upconversion of CO to various commodity chemicals. Imidazolium ([Im]) cathode combinations have been reported to selectively catalyze the 2e/2H reduction of CO to CO. Recently our laboratory has reported energy-efficient systems for CO production featuring inexpensive bismuth-based cathode materials and ILs comprised of 1,3-dialkylimidazolium cations.

pH-Driven Mechanistic Switching from Electron Transfer to Energy Transfer between [Ru(bpy)] and Ferrocene Derivatives.

The metal-to-ligand charge transfer excited states of [Ru(bpy)] (bpy = 2,2'-bipyridine) may be deactivated via energy transfer or electron transfer with ferrocene derivatives in aqueous conditions. Stern-Volmer quenching analysis revealed that the rate constant for [Ru(bpy)] excited-state quenching depends on solution pH when a ferrocenyl-amidinium derivative (Fc-am) containing a proton-responsive functionality tethered to the ferrocene center was present. By contrast, the rate constant with which the [Ru(bpy)] excited state is quenched by an analogous ferrocene derivative (ferrocenyl-trimethylammonium, Fc-mam) that lacks a protonic group does not depend on pH.

Synthesis and structure of palladium(II) complexes supported by -NHC pincer ligands for the electrochemical activation of CO.

A series of -NHC pincer complexes of palladium(II) have been prepared and characterized. These pyridyl-spaced dicarbene complexes ( ) were synthesized with substituents of varying steric bulk at the wingtip positions, which include R = methyl, ethyl, isopropyl, cyclohexyl, mesityl and 2,6-diisopropylphenyl. The synthesis of this library of complexes was accomplished either by direct metallation of the prerequisite pyridyl-spaced -imidazolium proligands with Pd(OAc) or via treatment with AgO to afford the corresponding silver carbenes, which were then transmetallated onto palladium.

Efficient Conversion of CO₂ to CO Using Tin and Other Inexpensive and Easily Prepared Post-Transition Metal Catalysts.

The development of affordable electrocatalysts that can drive the reduction of CO2 to CO with high selectivity, efficiency, and large current densities is a critical step on the path to production of liquid carbon-based fuels. In this work, we show that inexpensive triflate salts of Sn(2+), Pb(2+), Bi(3+), and Sb(3+) can be used as precursors for the electrodeposition of CO2 reduction cathode materials from MeCN solutions, providing a general and facile electrodeposition strategy, which streamlines catalyst synthesis. The ability of these four platforms to drive the formation of CO from CO2 in the presence of [BMIM]OTf was probed.

Efficient reduction of CO2 to CO with high current density using in situ or ex situ prepared Bi-based materials.

The development of inexpensive electrocatalysts that can promote the reduction of CO2 to CO with high selectivity, efficiency, and large current densities is an important step on the path to renewable production of liquid carbon-based fuels. While precious metals such as gold and silver have historically been the most active cathode materials for CO2 reduction, the price of these materials precludes their use on the scale required for fuel production. Bismuth, by comparison, is an affordable and environmentally benign metal that shows promise for CO2 conversion applications.

Selective conversion of CO2 to CO with high efficiency using an inexpensive bismuth-based electrocatalyst.

The wide-scale implementation of solar and other renewable sources of electricity requires improved means for energy storage. An intriguing strategy in this regard is the reduction of CO2 to CO, which generates an energy-rich commodity chemical that can be coupled to liquid fuel production. In this work, we report an inexpensive bismuth-carbon monoxide evolving catalyst (Bi-CMEC) that can be formed upon cathodic polarization of an inert glassy carbon electrode in acidic solutions containing Bi(3+) ions.