Elucidating the Synergistic Role of K-Co-Cu Ternary Interfaces in Selective CO2 Hydrogenation to Ethylene: A Combined DFT and Microkinetic Modeling Study

Abstract Direct CO2 hydrogenation to value-added hydrocarbons provides a pivotal route for carbon resource recycling, yet achieving high selectivity toward specific products remains a significant challenge. In this study, we combined density functional theory calculations with microkinetic modeling (MKM) to systematically investigate the catalytic performance of a series of K2O-promoted Co2C surfaces, including K/Co2C, K/Cu4-Co2C, K/Cu-Co2C(int), and K/Co2C-Cu(inv) for CO2 hydrogenation. The computational results reveal that both the Co/Cu atomic ratio and the interfacial structure decisively govern the catalytic performance. In particular, the K/Cu-Co2C(int) surface, with a Co:Cu atomic ratio of 1:1 and the largest heterogeneous interface, exhibits moderate adsorption strengths for CO2 and H2, effectively mitigating the active site poisoning that is prevalent on the pristine K/Co2C surface. Potential energy surface analyses demonstrate that this tailored interfacial structure significantly reduces the barriers for both the reverse water-gas shift reaction and C–C coupling, while kinetically suppressing the competing CO-insertion and methanation pathways. Furthermore, MKM and degree of rate control analyses confirm that the K/Cu-Co2C(int) interface model sustains balanced surface species coverage and delivers C2H4 turnover frequency several orders of magnitude higher than that of the other catalyst configurations across 500–700 K. This work clarifies the atomic-scale modulation mechanism of K-Co-Cu ternary interfaces and provides guidance for the rational design of catalysts for selective CO2-to-olefins conversion.