Electrochemical NAD⁺ reduction is a promising method to regenerate NADH for enzymatic reactions. Many different electrocatalysts have been tested in the search for high yields of the 1,4-isomer of NADH, the active NADH, but aside from electrode material, other system parameters such as pH, electrode potential and educt concentration also play a role in NADH regeneration. The effect of these last three parameters and the mechanisms behind their influence on NADH regeneration was systematically studied and presented in this paper. With percentages of active NADH ranging from 10 to 70% and faradaic efficiencies between 1 and 30%, it is clear that all three system parameters drastically affect the reaction outcome. As a proof of principle, the NAD+ reduction in the presence of pyruvate and lactate dehydrogenase was performed. It could be shown that the electrochemical NADH regeneration can also be done successfully in parallel to enzymatically usage of the regenerated cofactor.

Heat Treatment of martensitic stainless steels is used to increase the hardness that is caused by several microstructure changes. But such a treatment does affect both mechanical properties and corrosion resistance. Existing studies about the effect of austenitizing on the material properties and the corrosion resistance show contradictory results. Here we reveal the different effects of austenitizing on the passive layer of stainless steel and thus the corrosion resistance, thermodynamic phase calculations, microstructure investigations and various electrochemical measurements are performed. By potentiodynamic polarization scans the pitting potential, the critical pitting potential and the corrosion current are determined. Impedance spectroscopy are used to gain deeper insight into the passive layer properties. The results show a strong dependency of the corrosion behavior on the heat treatment where the governing corrosion mechanism are affected differently.

The phenomenon of passivity is crucial for many areas of our technological and metal-based civilization. Nevertheless, the mechanisms leading to passivity are still under investigation and not fully understood. Modeling passive film growth can bring insights into these processes, which are experimentally hard or impossible to access. Therefore, this paper presents a comprehensive model which can describe oxide film growth and dissolution under an external potential for various metal oxides. The simulation gives insights into the defect concentrations and electric field during passive film growth and film dissolution and delivers an anodic transpassive dissolution mechanism. The simulation is compared to experiments derived from the oxidation of iron electrodes and shows very good agreement. The addition of a transpassive dissolution mechanism to oxide film models is the next step toward model-based corrosion prediction.

The development of novel structural materials with increasing mechanical requirements is a very resource-intense process if conventional methods are used. While there are high-throughput methods for the development of functional materials, this is not the case for structural materials. Their mechanical properties are determined by their microstructure, so that increased sample volumes are needed. Furthermore, new short-time characterization techniques are required for individual samples which do not necessarily measure the desired material properties, but descriptors which can later be mapped on material properties. While universal micro-hardness testing is being commonly used, it is limited in its capability to measure sample volumes which contain a characteristic microstructure. We propose to use alternative and fast deformation techniques for spherical micro-samples in combination with classical characterization techniques such as XRD, DSC or micro magnetic methods, which deliver descriptors for the microstructural state.

The formation and breakdown of passive layers due to pitting corrosion are a major cause of failure of metal structures. The investigation of passivation and pitting corrosion requires two different electrochemical measurements and is therefore a time consuming process. To reduce time in material characterization and to study the interactions of both mechanisms, here, a combined experiment addressing both phenomena is introduced. In the presented electrolyte the different corrosion mechanisms are distinguished and investigated by cyclic voltammograms and polarization scans. The measurements show a passive area, metastable pit growth, and pitting corrosion as well as repassivation. The pitting corrosion is separated from additional dissolution processes and the standard deviation of the corrosion potential is smaller than in other electrolytes. Both passivation and pitting corrosion can be observed in one measurement without additional corrosion attacks. The deviation between different measurements of the same steel is small; this is helpful for the screening of similar materials.