The power-to-gas process for the chemical storage of renewable energy in methane as a storage molecule requires a carbon source, for which industrial exhaust gases are very promising because of their availability in large quantities. The composition of these gas streams, however, is often characterized by a mixture of CO and CO2. Because of the rather complex reaction mechanism, though, the methanation of CO/CO2 mixtures using nickel catalysts is not yet fully understood, and appropriate reaction kinetics required for the reactor design are still lacking. Therefore, we report the experimental results on the methanation of various mixtures of CO and CO2. The data are further evaluated by a model-based approach in order to derive reaction kinetics capable for the reactor design in a typical range of operating conditions. The results also reveal two kinetic regimes depending on the fraction of CO in the CO/CO2 mixture, which is accounted for in the proposed kinetics.

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The barrier to charge carrier injection across the semiconductor/electrode interface is a key parameter in the performance of organic transistors and optoelectronic devices, and the work function of the electrode material plays an important role in determining the size of this barrier. We present a new, chemical route for making metal surfaces with low work functions, by functionalizing gold surfaces with self‐assembled monolayers of n,n‐dialkyl dithiocarbamates. Ultraviolet photoemission spectroscopy measurements show that work functions of 3.2 eV ± 0.1 eV can be achieved using this surface modification. Electronic structure calculations reveal that this low work function is a result of the packing‐density, polarization along the N‐C bond, and charge rearrangement associated with chemisorption. We demonstrate that electrodes functionalized with these monolayers significantly improve the performance of organic thin‐film transistors and can potentially be employed in charge selective contacts for organic photovoltaics.

The Power-to-Gas (PtG) process offers the opportunity to store fluctuating renewable energy in form of chemical energy by hydrogenating carbon oxides into methane. In addition, potential carbon point sources often consist of CO/CO2 (COx) mixtures. Hence, reactor design requires kinetic models valid for unsteady-state operation and a broad spectrum of feed gas compositions. In order to provide the required experimental data basis for derivation of kinetic expressions valid under transient conditions, the dynamic response of a continuously operated fixed-bed methanation reactor is studied by applying periodic step-changes in the feed composition. The obtained results are evaluated based on a simple reactor model, providing the molar flow rate exchanged between the gas bulk and the solid surface for CO, CO2, CH4, and H2O. The results further reveal that the transient kinetic processes at the catalyst surface strongly affect the reactor response under reaction conditions of technical relevance.

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