Bringing Electrochemical Three-Dimensional Printing to the Nanoscale.

Nanoscale 3D printing is attracting attention as an alternative manufacturing technique for a variety of applications from electronics and nanooptics to sensing, nanorobotics, and energy storage. The constantly shrinking critical dimension in state-of-the-art technologies requires fabrication of complex conductive structures with nanometer resolution. Electrochemical techniques are capable of producing impurity-free metallic conductors with superb electrical and mechanical properties, however, true nanoscale resolution (<100 nm) remained unattainable. Here, we set new a benchmark in electrochemical 3D printing. By employing nozzles with dimensions as small as 1 nm, we demonstrate layer-by-layer manufacturing of 25 nm diameter voxels. Full control of the printing process allows adjustment of the feature size on-the-fly, printing tilted, and overhanging structures. On the basis of experimental evidence, we estimate the limits of electrochemical 3D printing and discuss the origins of this new resolution frontier.

New Insights Into the Role of Imidazolium-Based Promoters for the Electroreduction of CO2 on a Silver Electrode.

The electrochemical reduction of CO2 to CO is a reaction of central importance for sustainable energy conversion and storage. Herein, structure-activity relationships of a series of imidazolium-based cocatalysts for this reaction are described, which demonstrate that the C4- and C5-protons on the imidazolium ring are vital for efficient catalysis. Further investigation of these findings led to the discovery of new imidazolium salts, which show superior activity as cocatalysts for the reaction, i.e., CO is selectively produced at significantly lower overpotentials with nearly quantitative faradaic yields for CO.

Robust High-performance Dye-sensitized Solar Cells Based on Ionic Liquid-sulfolane Composite Electrolytes.

Novel ionic liquid-sulfolane composite electrolytes based on the 1,2,3-triazolium family of ionic liquids were developed for dye-sensitized solar cells. The best performing device exhibited a short-circuit current density of 13.4 mA cm(-2), an open-circuit voltage of 713 mV and a fill factor of 0.65, corresponding to an overall power conversion efficiency (PCE) of 6.3%. In addition, these devices are highly stable, retaining more than 95% of the initial device PCE after 1000 hours of light- and heat-stress. These composite electrolytes show great promise for industrial application as they allow for a 14.5% improvement in PCE, compared to the solvent-free eutectic ionic liquid electrolyte system, without compromising device stability.

Palladium-catalyzed aminocarbonylation of alkynes to succinimides.

Succinimide derivatives are useful building blocks for the synthesis of natural products and drugs. We describe an efficient route to succinimide derivatives comprising Pd(xantphos)Cl2-catalyzed aminocarbonylation of alkynes with aromatic or aliphatic amines in the presence of p-TsOH. The utility of this route is demonstrated with the synthesis of a large number of succinimide compounds including an important photochromic molecule.

Enhancing the stability of porphyrin dye-sensitized solar cells by manipulation of electrolyte additives.

The use of porphyrin-based photosensitizers with superior light-harvesting properties has enabled the power conversion efficiency of dye-sensitized solar cells (DSCs) to reach 13 % under full sun illumination. However, a major limitation of such devices corresponds to the volatility of the solvent used so far for the electrolyte, which prevents practical applications. In this work, we describe a porphyrin-ionic liquid DSC, which not only affords the highest efficiency reported to date, but is also stable for more than 300 h under continuous full sun illumination at 60 °C. Furthermore, we identify a previously unreported pathway for device degradation, and show that the addition of N-methylbenzimidazole and a thiocyanate salt to the electrolyte is critical to obtaining long-lived devices.

Highly stable dye-sensitized solar cells based on novel 1,2,3-triazolium ionic liquids.

We describe the design and synthesis of novel low viscosity bicyclic 1,2,3-triazolium ionic liquids. These new salts are applied as nonvolatile electrolytes in dye-sensitized solar cells, affording efficiencies up to 7.07% at low light intensities, and 6.00% when illuminated at 100 mW cm(-2). The devices are highly stable, retaining ca. 90% of their initial performance even after 1000 h of sun testing at 60 °C. The results obtained with these new ionic liquids compare very favorably to benchmark ionic liquid-based devices and illustrate the potential of the triazolium family of salts to compete with their imidazolium counterparts.