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We demonstrate that for high yield wet synthesis of monodispersed nanoparticles high surfactant content bicontinuous microemulsions offer an advantageous template as particle size is limited by the embedding matrix whereas particle aggregation is largely prohibited by its structure. We synthesized platinum nanoparticles varying the reaction rate, metal precursor and reducing agent type and concentration, and the composition of the microemulsion in water content and oil type. High yields of up to 0.4% of metal produced per weight of template were achieved without affecting the particle size, ca. 2 nm. We showed that our method is robust in the sense that particle size is hardly dependent on synthesis conditions. This is attributed to the fact that the packing of surfactant on nanoparticle surfaces is the only parameter determining the particle size. It can only be slightly varied with ionic strength, headgroup hydration, and tail solvency through oil variation. Water content mainly affects the microemulsion stability and through that the colloidal stability of the nanoparticles. Hydrazine as a reducing agent poses a special case as it causes dimerization of the surfactant and hence modifies the surfactant parameter as well as the stability. Finally, we highlighted the differences in comparison to nanoparticle synthesis in standard water-in-oil microemulsions, and we propose a mechanism of particle formation.

In industrial electrochemical processes it is of paramount importance to achieve efficient, selective processes to produce valuable chemicals while minimizing the energy input. Although the electrochemical reduction of CO2 has received a lot of attention in the last decades, an economically feasible process has not yet been developed. Typically, the electrochemical reduction of CO2 is paired to water oxidation, forming oxygen, but an alternative strategy would be coupling the CO2 reduction reaction to an oxidation in which a higher-value product is co-produced, significantly improving the economic feasibility for CO2 reduction as a whole. Importantly, both reactions need to be chosen wisely, to ensure their compatibility and to minimize the voltage requirements for the redox system. In this study, as an example of this approach, we demonstrate such a match-the electroreduction of CO2 to CO, paired with the electrooxidation of 1,2-propanediol to lactic acid. Combining these reactions decreases energy consumption by ca. 35%, increases of product value of the system, and results in combined faradaic efficiencies of up to 160% when compared to the CO2 reduction reaction in which oxygen is formed in the anode.

The dissolution of noble-metal catalysts under mild and carbon-preserving conditions offers the possibility of in situ regeneration of the catalyst nanoparticles in fuel cells or other applications. Here, we report on the complete dissolution of the fuel cell catalyst, platinum nanoparticles, under very mild conditions at room temperature in 0.1 M HClO4 and 0.1 M HCl by electrochemical potential cycling between 0.5-1.1 V at a scan rate of 50 mV s(-1) . Dissolution rates as high as 22.5 μg cm(-2) per cycle were achieved, which ensured a relatively short dissolution timescale of 3-5 h for a Pt loading of 0.35 mg cm(-2) on carbon. The influence of chloride ions and oxygen in the electrolyte on the dissolution was investigated, and a dissolution mechanism is proposed on the basis of the experimental observations and available literature results. During the dissolution process, the corrosion of the carbon support was minimal, as observed by X-ray photoelectron spectroscopy (XPS).

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Microemulsions are exciting systems that are promising as tuneable self-assembling templating reaction vessels at the nanoscale. Determination of the nano-structure of microemulsions is, however, not trivial, and there are fundamental questions regarding their design. We were able to reproduce experimental data for an important microemulsion system, sodium-AOT-n-heptane-water, using coarse-grained simulations involving relatively limited computational costs. The simulation allows visualization and deeper investigation of controversial phenomena such as bicontinuity and ion mobility. Simulations were performed using the Martini coarse-grained force field. AOT bonded parameters were fine-tuned by matching the geometry obtained from atomistic simulations. We investigated several compositions with a constant ratio of surfactant to oil while the water content was varied from 10 to 60% in weight. From mean square displacement calculation of all species, it was possible to quantify caging effects and ion mobility. Average diffusion coefficients were calculated for all charged species and trends in the diffusion coefficients were used to rationalize experimental conductivity data. Especially, the diffusion coefficient of charged species qualitatively matched the variation in conductivity as a function of water content. The scattering function was calculated for the hydrophilic species and up to 40% water content quantitatively matched the experimental data obtained from small angle X-ray scattering measurements. For higher water contents, discrepancies were observed and attributed to a nearby phase separation. In particular, bicontinuity of water and oil was computationally visualized by plotting the coordinates of hydrophilic beads. Equilibrated coarse-grained simulations were reversed to atomistic models in order both to compare ion mobility and to catch finer simulation details. Especially, it was possible to capture the intimate ion pair interaction between the sodium ion and the surfactant head group.

A PFSA‐stabilized Pt‐catalyst supported on a novel carbon material, carbon nano networks (CNNs), was synthesized. To benchmark its performance, it was compared to a commercial catalyst, supported on an amorphous carbon support, and to a PFSA stabilized Pt catalyst supported on commercial carbon nano tubes (CNTs). The PFSA‐Pt/CNNs exhibit improved performance compared to commercial catalysts in terms of ORR kinetic activity and durability. Even though PFSA‐Pt/CNTs should show comparable behavior to PFSA‐Pt/CNNs, our experimental results show a slightly superior performance. Optimization of the CNN synthesis route is expected to improve their properties as a carbon support. Since CNN mass production is expected to be cheaper than for CNTs because of the simplicity of the synthesis route, we conclude that CNNs are a promising material for the fuel cell market.

Amongst the main challenges of catalyst materials for Proton Exchange Membrane Fuel Cells (PEMFCs) are activity and durability. Here we report on the synthesis of monodisperse nanoparticles and stabilization with traces of the surfactant, here Na‐AOT (bis‐(2‐ethylhexyl) sulfosuccinate sodium salt), used in the synthesis procedure. The surfactants prevent agglomeration and reduce Ostwald ripening. We compare the performance of Pt catalyst nanoparticles synthesized in dense microemulsions, Na‐AOT/heptane/water and Triton X‐100/toluene/water, with a commercial state‐of‐the‐art catalyst for the Oxygen Reduction Reaction (ORR). The produced catalyst nanoparticles were extracted onto a carbon support, Vulcan XC‐72R, washed and activated by heat‐treatment, which led to heavy agglomeration, or by electrochemical treatment, which led to an enhanced activity for ORR. Additionally, in comparison to the other two catalysts an increased durability of the platinum nanoparticles synthesized in the microemulsion of Na‐AOT/heptane/water was observed.