High-Throughput Exploration of Structural and Electrochemical Properties of the High-Entropy Nitride System (Ti–Co–Mo–Ta–W)N

High-entropy nitrides are largely unexplored materials with high potential to show good mechanical properties, high stability against chemicals, but also promising electrocatalytic properties. The latter is due to their good electrical conductivity compared to (high-entropy) oxides. The high-entropy nitride system (Ti–Co–Mo–Ta–W)N is chosen for investigation based on the idea to combine binary and ternary nitrides, which show good water-splitting activities. Thin-film materials libraries with continuous composition spreads are deposited using reactive cosputter deposition at 300 and 500 °C. X-Ray diffraction results show that the films consist of a single-phase solid solution in NaCl-type structure. The surface morphology is examined using scanning electron and atomic force microscopy. (Ti–Co–Mo–Ta–W)N films show low resistivity values in the range from 1.72 to 5.2 μΩ cm. Their oxygen evolution reaction activity is measured using a scanning droplet cell, with a maximum current density of 1.78 mA cm−2 at 1700 mV versus reversible hydrogen electrode. The results indicate that stability is a challenge for high-entropy nitrides, at least for their use as oxygen-related electrocatalytic reactions.