Co-Enriched High Entropy Oxides for Efficient Continuous Electrochemical Methane Conversion: Catalytic Performance and Sustainability Insights

Abstract

The 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/g_cat/hr at 1.6 V_RHE, 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/g_cat/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.