High catalytic efficiency and long‐term stability are two main components for the performance assessment of an electrocatalyst. Previous attention has been paid more to efficiency other than stability. The present work is focused on the study of the stability processed on the FeCoNiRu high‐entropy alloy (HEA) in correlation with its catalytic efficiency. This catalyst has demonstrated not only performing the simultaneous hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with high efficiency but also sustaining long‐term stability upon HER and OER. The study reveals that the outstanding stability is attributed to the spinel oxide surface layer developed during evolution reactions. The spinel structure preserves the active sites that are inherited from the HEA's intrinsic structure. This work will provide an insightful direction/pathway for the design and manufacturing activities of other metallic electrocatalysts and a benchmark for the assessment of their efficiency–stability relationship.

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Transformation optics (TO) is a powerful technique for manipulating diffusive transport, such as heat and electricity. While most studies have focused on individual heat and electrical flows, in many situations thermoelectric effects captured via the Seebeck coefficient may need to be considered. Here we apply a unified description of TO to thermoelectricity within the framework of thermodynamics and demonstrate that thermoelectric flow can be cloaked, diffused, rotated, or concentrated. Metamaterial composites using bilayer components with specified transport properties are presented as a means of realizing these effects in practice. The proposed thermoelectric cloak, diffuser, rotator, and concentrator are independent of the particular boundary conditions and can also operate in decoupled electric or heat modes.

Quaternary chalcogenides composed of earth-abundant and primarily nontoxic constituents are currently being explored for thermoelectric applications. The representatives of this class, CuZn2InTe4 and AgZn2InTe4, have been synthesized, and here, we present a comparative study of their structure–property relations using first principles simulations. Our calculations show that the lattice structure for both materials is very similar in terms of characteristic atomic distances and lattice structures, which compare well with experimental data. The electronic structure results indicate that both materials are direct gap semiconductors whose electron localization and charge transfer properties reveal polar covalent bonding in the lattice. The calculated phonon structure shows dynamic stability with unique vibrational properties for each material.

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