Heewon MinCheolho KimShu‐Ya LinJiyun ChoiYunjeong SimBOR-YIH YUJun Hyuk Moon2025-05-062025-05-062025https://www.scopus.com/record/display.uri?eid=2-s2.0-105000878555&origin=resultslisthttps://scholars.lib.ntu.edu.tw/handle/123456789/728933The electrochemical conversion of methane offers a sustainable alternative to traditional thermochemical syngas pathways; however, the rational design of catalysts that ensure high productivity remains a significant challenge. In this study, a high-entropy oxide (HEO) catalyst composed of Co, Cr, Fe, Mn, and Ni is explored, with a targeted element enriched, and identify that a Co-rich HEO demonstrates high efficiency in room-temperature electrochemical methane conversion. This analysis of the projected density of states (PDOS) reveals that Co sites in the HEO catalyst possess an optimally positioned p-band center for methane activation. The Co-rich HEO catalyst achieves an ethanol production rate of 12315 µmol/gcat/hr at 1.6 VRHE, with a Faradaic efficiency of 63.5%; a flow cell electrolyzer equipped with this catalyst achieves continuous methane-to-ethanol conversion at a rate of 26533 µmol/gcat/hr over 100 h. Process modeling evaluates the economic and environmental implications, demonstrating that a commercially viable process can be realized through economies of scale while significantly reducing CO₂ emissions.Co enrichmentelectrochemical methane conversionethanol productionhigh entropy oxideprocess sustainability[SDGs]SDG12journal article10.1002/adma.202418767