From Bad Electrochemical Practices to an Environmental and Waste Reducing Approach for the Generation of Active Hydrogen Evolving Electrodes.

The electrodeposition of noble metals using corresponding dissolved metal salts represents an interesting process for the improvement of the electrocatalytic hydrogen evolution reaction (HER) properties of less active substrate materials. The fact that only a small fraction of the dissolved noble metals reaches the substrate represents a serious obstacle to this common procedure. We therefore chose a different path. It was found that the HER activity of Ni42 alloy drastically increased (η=140 mV at j=10 mA cm-2 ; pH 1) when a platinum counter electrode was used during polarization experiments in acid. This improvement was caused by a platinum transfer from the platinum anode to the steel cathode, a process which occurred simultaneously to the hydrogen evolution. The negligible accumulation of Pt (26 µg) in the electrolyte turns this straight-forward transfer procedure into a highly cost-effective, environmentally friendly, and waste reducing approach for the generation of cheap, stable and effective HER electrodes.

Determination of Reaction Enthalpies of Synthesizing ß-Li3PS4 in Tetrahydrofuran.

While some promising materials for all-solid-state batteries are already extensively investigated in a lab scale, the transferability to mass production is still a limiting factor. ß-lithium thiophosphate (ß-Li3PS4) has good ionic conductivity and can be synthesized wet-chemically, which opens up the possibility for scale-up. For safe upscaling, the enthalpies of the synthesis steps need to be examined in order to handle exothermic and endothermic processes. Here, the reaction enthalpies of the wet-chemical synthesis of ß-Li3PS4 in tetrahydrofuran (THF) are determined. The synthesis routine is established in a lab scale, and the synthesis success is confirmed via X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS). The reaction of the educts in THF is investigated using a reaction calorimeter and shows a strongly exothermic process. The subsequent processes are examined using differential scanning calorimetry with thermogravimetric analysis and show a strong endothermic process during solvent removal and a slightly exothermic process during crystallization.