Multifunctional assessment of rock-salt (Co$_{0.2}$Cu$_{0.2}$Mg$_{0.2}$Ni$_{0.2}$Zn$_{0.2}$)O High-Entropy OxideSkalar, Tina (Avtor) Žgajnar Gotvajn, Andreja (Avtor) Legan, Maša (Avtor) Kostinjuk, Andrij Olegovič (Avtor) Likozar, Blaž (Avtor) Tatar, Dalibor (Avtor) Djerdj, Igor (Avtor) Marinšek, Marjan (Avtor) carbon dioxide utilizationhigh-entropy oxidesmethanolphytotoxicityIn this study, high-entropy oxide (HEO) (Co$_{0.2}$Cu$_{0.2}$Mg$_{0.2}$Ni$_{0.2}$Zn$_{0.2}$)O was synthesized via two different approaches, combustion synthesis (CS) and a solvent-deficient mechanochemical method (SDM), and comparatively investigated in terms of structural properties, catalytic performance in CO$_2$ hydrogenation, and environmental impact through phytotoxicity assessment. X-ray diffraction confirmed the formation of a phase-pure cubic rock-salt structure (Fm-3m) for both synthesis routes. However, the CS-derived material exhibited a smaller crystallite size, a higher lattice microstrain, and more pronounced structural anisotropy compared to the SDM counterpart, while both materials showed relatively low specific surface areas. Catalytic testing was performed for CO$_2$ hydrogenation at 20 bar, H$_2$/CO$_2$ = 3, and 200°C–300°C. Both HEO catalysts showed high selectivity toward methanol. The CS catalyst demonstrated markedly superior performance, achieving up to ∼16 mol% CO$_2$ conversion and significantly higher methanol space-time yield (4.2 mmol gcat$^{−1}$ h$^{−1}$) at 300°C compared to the SDM sample. The enhanced activity is attributed to a higher defect density and lattice distortion induced by the combustion route. Environmental assessment using Lemna minor revealed that metal leaching from the HEOs significantly affected phytotoxicity. The CS-derived material showed higher leaching of Cu, Co, and Ni, highlighting a trade-off between catalytic activity and environmental stability.20262026-10-09 12:12:40Članek v reviji189581sl