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    Machine-learning-accelerated density functional theory screening of Cu-based high-entropy alloys for carbon dioxide reduction to ethylene
    (2025-03-01)
    Rittiruam, Meena
    ;
    Khamloet, Pisit
    ;
    Tiwtusthada, Sirapat
    ;
    Ektarawong, Annop
    ;
    Saelee, Tinnakorn
    Computational screening of high-entropy alloy (HEA) catalysts as alternatives to the typical Cu electrocatalyst for CO<inf>2</inf> reduction reaction (CO<inf>2</inf>RR) has been extensively focused on C<inf>1</inf> products, but C<inf>2+</inf> products have received significantly less attention. This work optimized CuZnPdAgAu HEA catalyst composition for CO<inf>2</inf>RR to ethylene via density functional theory and supervised machine learning regression techniques. Candidates were identified from 106,045 HEA data for enthalpy of adsorption of *CO<inf>2</inf>, *H, *HOCCOH, and *C<inf>2</inf>H<inf>4</inf> species, and the Gibbs free energy of *H. The electrocatalytic properties during the reaction were examined on the surface of the optimized HEA candidate – Cu<inf>0.36</inf>Zn<inf>0.18</inf>Pd<inf>0.10</inf>Ag<inf>0.18</inf>Au<inf>0.18</inf> benchmarked to Cu (111). The Pd site of such a candidate functions as the active site for the CO<inf>2</inf> activation step. In terms of catalytic activity, it showed lower Gibbs free energy for the potential determining step – the *OCCOH formation step compared to that on the Cu (111). Insight into electronic properties demonstrated that the candidate reduces the uphill reaction energy for *HOCCOH production pathway due to increased electron density in the C–C bond, donated from two Cu sites. It is shown that the HEA catalyst candidate has the potential for CO<inf>2</inf>RR targeting ethylene, an alternative to a common Cu catalyst.
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    Physical, mechanical and magnetic properties of cobalt-chromium alloys prepared by conventional processing
    (2017-01-01)
    Poolphol, Nattakarn
    ;
    Sakkaew, Tatchakorn
    ;
    Kachin, Keerati
    ;
    Jantaratana, Pongsakorn
    ;
    Vittayakorn, Wanwilai
    In this work, the cobalt-chromium alloys (Co-xCr) with various compositions, x = 0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 wt.%, were prepared by conventional powder metallurgical processing cooperated with cold isostatic press technique (CIP) followed by traditional sintering in argon media. The effects of chemical compositions on phase formation, microstructure and properties of cobalt-chromium alloys were studied. Phase evolution, densification, microstructure, mechanical and magnetic properties of this system were investigated. X-ray diffraction patterns show the existence of cobalt peak along with chromium peak and the intensity of Cr peaks increase with increasing of x. SEM micrographs reveal high dense of very large irregular-shaped-grains and the average grain size of this alloy decreases with increase of x. Physical, mechanical and magnetic properties strongly depend on chemical composition.