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The strong effect of the electrolyte cation on the activity and selectivity of the CO2 reduction reaction (CO2RR) can only be understood and controlled if the cation's effect on the interfacial potential distribution is known. Using CO (the key intermediate in the CO2RR) adsorbed on Pt as a probe molecule, and combining IR spectroscopy, capacitance measurements and ab initio molecular dynamics, we show that the cation size determines the location of the outer Helmholtz plane, whereby smaller cations increase not just the polarisation but, most importantly, the polarizability of adsorbed CO (COad) and the accumulation of electronic density on the oxygen atom of COad. This strongly affects its adsorption energy, the degree of hydrogen bonding of interfacial water to COad and the degree of polarisation of water molecules in the cation's solvation shell, all of which can deeply affect the subsequent steps of the CO2RR.

The voltammetric detection of less than 1 ppm of ammonia gas in the room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Cmim][NTf]) is demonstrated using low-cost planar electrode devices. Three commercially available planar devices were employed, all with platinum (Pt) working electrodes: a thin-film electrode (TFE), a screen-printed electrode (SPE), and a microarray thin film electrode (MATFE), along with an "ideal" conventional Pt microdisk electrode for comparison. The microholes on the recessed MATFE were also "filled" with electrodeposited platinum, to improve radial diffusion characteristics to the microhole and generate higher current densities. Current density was lowest for the TFE and SPE surfaces (linear diffusion), higher for the MATFE (mixed radial and linear diffusion), and even higher for the filled MATFE (predominantly radial diffusion). Linear sweep voltammetry (LSV) and potential-step chronoamperometry (PSCA) at 10-100 ppm of NH gave linear behavior for current vs concentration. Limits of detection (LODs) were in the range of ca. 1-9 ppm, lower than the minimum exposure limit (25 ppm) for NH. The best stability, reproducibility, and the lowest LODs were observed on the recessed and filled MATFEs. These were employed to detect lower concentrations of ammonia (0.1-2 ppm), where linear behavior was also observed, and LODs of 0.11 (recessed) and 0.02 (filled) were obtained. These are believed to be the lowest LODs (to date) reported for ammonia gas in neat ionic liquids. This is highly encouraging and suggests that RTILs and low-cost miniaturized MATFEs can be combined in amperometric sensor devices to easily and cheaply detect ammonia gas at ppb concentrations.

We present a straightforward strategy for the synthesis of highly charged poly(ionic liquid)-functionalized particles in low-polarity solvents. A series of cationic liquid monomers consisting of a tetraalkyl ammonium cation and a fluorinated tetrakis[phenyl] borate anion linked, via a C3-alkyl chain, to a methacrylate unit were synthesized. The addition of this ionic monomer to a conventional dispersion polymerization of methyl methacrylate and methacrylic acid at 80 °C in a mixed dodecane/hexane solvent yielded spherical, highly monodisperse particles with mean diameters of between ~50 and 2500 nm with high electrophoretic mobility and stability in nonpolar solvents such as dodecane. The surface potential in dodecane could be adjusted in the range from 0 to 180 ± 9 mV by altering the ratio of ionic monomer to methacrylate monomers. The particles open up new opportunities for the electrostatic assembly of nanoparticles and organized structures in nonpolar environments.

Macroporous platinum structures have been prepared by electrodeposition in the interstitial spaces between a 500 nm polystyrene sphere template, onto platinum and glassy carbon electrodes. The structures were analysed with scanning electron microscopy and confocal microscopy. These electrodes are employed for the electrochemical oxidation of hydrogen in the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2]). The behaviour on the porous electrodes showed obvious thin-layer characteristics in the cyclic voltammetry, with a strong tendency for hydrogen to accumulate and remain in the pores after being removed from the cell. Plots of peak current vs concentration (10-100 % H2) were linear, but currents continued to increase over time. The sensitivities (gradients) of the calibration plots were the highest for the platinum porous structures (compared to the bare, or nanoparticle-modified surfaces). Due to the accumulation of gas, such modified electrodes could be employed as leak-detectors for very low concentrations of hydrogen.

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The synthesis of thin films of metal organic frameworks (MOFs) is a rapidly growing area owing to the use of these highly functional nanomaterials for various applications. In this study, a thin layer of a typical MOF, copper benzene tricarboxylate (HKUST-1), was synthesized by electrodeposition on a glassy carbon (GC) electrode using a potential-step chronoamperometric technique at room temperature. Various characterization techniques including Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to verify the successful deposition of the MOF film and its structure. The electrodeposited MOF crystals showed cuboctahedral morphology with macropores. The MOF-modified electrode was applied for hydrogen gas sensing in a room temperature ionic liquid (RTIL) for the first time.A four-fold increase in current was observed compared to a precious metal surface, i.e. platinum, and the electrode exhibited significant catalytic activity compared to the bare GC electrode, making it a very promising low cost material for hydrogen gas sensing applications.