Efficient Electrocatalytic CO2 Reduction Driven by Ionic Liquid Buffer-Like Solutions.

Electrocatalysis of CO2 reduction in aqueous electrolytes containing the ionic liquid (IL) 1-n-butyl-2,3-dimethylimidazolium acetate ([BMMIm][OAc]) and DMSO proceeded at low overpotentials (-0.9 V vs. Ag/AgCl) at commercially-available Au electrodes, with high selectivity for CO production (58 % faradaic efficiency at -1.6 V vs. Ag/AgCl). 0.43 mol CO2 per mol IL could be absorbed into the electrolyte at atmospheric pressure, forming bicarbonate and providing a constant supply of dissolved CO2 to the surface of the electrode. Electrocatalysis of CO2 reduction in the electrolyte was facilitated by stabilization of CO2 radical anions by the imidazolium cations of the IL and buffer-like effects with bicarbonate.

CO2 Electroreduction in Ionic Liquids.

CO2 electroreduction is among the most promising approaches used to transform this green-house gas into useful fuels and chemicals. Ionic liquids (ILs) have already proved to be the adequate media for CO2 dissolution, activation, and stabilization of radical and ionic electrochemical active species in aqueous solutions. In general, IL electrolytes reduce the overpotential, increase the current density, and allow for the modulation of solution pH, driving product selectivity. However, little is known about the main role of these salts in the CO2 reduction process the assumption that ILs form solvent-separated ions. However, most of the ILs in solution are better described as anisotropic fluids and display properties of an extended cooperative network of supramolecular species. That strongly reflects their mesoscopic and nanoscopic organization, inducing different processes in CO2 reduction compared to those observed in classical electrolyte solutions. The major aspects concerning the relationship between the structural organization of ILs and the electrochemical reduction of CO2 will be critically discussed considering selected recent examples.

Imprinted Naked Pt Nanoparticles on N-Doped Carbon Supports: A Synergistic Effect between Catalyst and Support.

A synergistic effect resulting from the interaction of small (2.4-3.1 nm) naked Pt nanoparticles (NPs) imprinted on N-doped carbon supports is evidenced by structural, electronic and electrochemical characterization. The size and distribution of the sputtered Pt NPs are found to be related to the nature of the support because Pt NPs are preferentially located at Ngraphitic sites. In addition, Rutherford backscattering shows that a deeper penetration of the Pt NPs is obtained in the N-doped carbon support with larger pore diameters. The ligand effect of the N-doped carbon supports is found to occur by electron donation from Npyrrolic and Ngraphitic sites to the Pt NPs and the electron acceptor behavior of the C=Npyridinic sites. The carbon matrix acquires a basic characteristic (electron-richer, metallic behavior) capable of interacting with metallic NPs akin to a bimetallic-like system. The imprinted Pt NPs are active catalysts for oxidation, although displaying poor catalytic activity for reduction reactions. The catalyst N-doped carbon supports play an important role in the overall catalytic process, rather than only acting as a simple active phase carrier.

Sputtering deposition of gold nanoparticles onto graphene oxide functionalized with ionic liquids: biosensor materials for cholesterol detection.

Ionic liquid (IL)-functionalized graphene oxide (GO) containing gold nanoparticles (Au NPs) (5.4-5.9 nm) deposited by sputtering combined with cholesterol oxidase appears to be a suitable and efficient biosensor for total cholesterol detection. These biosensors showed good linear range (25-340 µmol L-1) for total cholesterol determination by colorimetric tests. In addition, control experiments in the presence of interferents demonstrated that the hybrid materials provided a selective detection of total cholesterol. The biosensing activities obtained for the hybrid materials indicate that these compounds are potential biosensors for clinical applications.