Synergistic Surface–Interface Catalysis in Potassium-Loaded Cu/CoO_<i>x</i> Catalysts to Boost Ethanol Production from CO₂ Hydrogenation

Nowadays, ethanol production from CO₂ hydrogenation has emerged as a viable pathway for CO₂ capture and efficient utilization. However, catalysts based on nonprecious metals still face significant challenges in achieving high catalytic efficiency for ethanol production. In this study, we constructed K-incorporated CuCo-based catalysts, which were obtained from Cu-Co-Al layered double hydroxide precursors, for efficient CO₂ hydrogenation to produce ethanol. It was shown that the incorporation of K into catalysts could finely tune the electronic structures of copper and cobalt species, thereby promoting the formation of substantial surface Co²⁺-O_v-Co²⁺ (O_v: oxygen vacancy), Co-O-K, and Cu⁺-O-K structures. Notably, as-constructed Cu/CoO_<i>x</i> catalyst bearing a K loading of 3 wt % achieved an impressively high ethanol selectivity of 38.8% at 200 °C as well as a remarkably high ethanol production rate of 2.76 mmol_EtOH·g_cat^-1·h^-1 at 260 °C. Based on multiple structural characterizations, spectroscopic analysis, and density functional theory calculations, it was uncovered that defective CoO_<i>x</i> and Cu⁺-O-K structures promoted the generation of formate intermediates during CO₂ hydrogenation, and meanwhile, the effective coadsorption of K⁺ and Cu⁺ stabilized formate intermediates. Accordingly, active K⁺, Cu⁺ and CoO_<i>x</i> species over CuCo-based catalysts exhibited synergistic catalysis, which significantly improved the CH_<i>x</i>-HCOO coupling process at K-loaded Cu/CoO_<i>x</i> interfaces to boost ethanol production. This study presents a novel surface-interface engineering approach for designing non-noble-metal-based catalysts for efficient ethanol production from CO₂ hydrogenation.