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 degrees 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 mu omega 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. The high-entropy nitride system (Ti-Co-Mo-Ta-W)N is reactively sputtered as materials libraries covering large compositional ranges. These libraries are used as a test platform for the oxygen evolution reaction and for investigating the stability of the nitride films against oxidation during the catalytic application using high-throughput characterization methods.image (c) 2023 WILEY-VCH GmbH

Automated summary

High-entropy nitrides are a class of unexplored materials with good mechanical properties, high stability against chemicals, and promising electrocatalytic performance. In this study, a high-entropy nitride system (Ti-Co-Mo-Ta-W)N is investigated, which combines binary and ternary nitrides showing good water-splitting activities. Thin-film materials libraries with continuous composition spreads are deposited using reactive cosputter deposition. The films exhibit a single-phase solid solution structure and low resistivity values. The oxygen evolution reaction activity of the (Ti-Co-Mo-Ta-W)N films is measured, and the results indicate that stability is a challenge for high-entropy nitrides in oxygen-related electrocatalytic reactions. The reactive sputtering method is used to prepare high-entropy nitride materials libraries, which serve as a test platform for studying the stability of nitride films during catalytic applications.