Hydrogenative coupling of CO₂ to ethanol presents a sustainable pathway for carbon neutralization, yet the fundamental active sites and reaction pathway/mechanism remain unclear. Here, we investigate CO₂ hydrogenative coupling over Cu/CeO_2−x catalysts, achieving an optimal CO₂ conversion of ~ 5% and ethanol selectivity of ~ 95% under 30 atm, H₂/CO₂ = 3, at 240 °C, and gas hourly space velocity (GHSV) = 120 mL·g_cat⁻¹·h⁻¹. We revealed that both Cu(I) and oxygen vacancies (O_v) serve as active sites, with turnover frequencies (TOFs) of 0.23 h⁻¹ per O_v site and 3.97 h⁻¹ per Cu(I) site, respectively. We also concluded that neither Cu(I) nor O_v can function independently; both Cu(I) and O_v are required for CO₂ activation and ethanol formation. Operando Fourier-transform infrared (FTIR) spectroscopy and density functional theory (DFT) calculations identify CH₂OH* and CH₂* as key intermediates in the C–C coupling step. These findings establish a mechanistic framework for CO₂ hydrogenative coupling and provide valuable insights for designing more efficient catalysts for ethanol synthesis from CO₂ conversion.

Atomically thin Pt nanolayers were synthesized on the surface of Mo₂TiC₂ MXenes and used for the catalytic dehydrogenation of ethane and propane into ethylene and propylene, two important chemicals for the petrochemical industry. As compared with Pt nanoparticles, the atomically thin Pt nanolayer catalyst showed superior coke-resistance (no deactivation for 24 h), high activity (turnover frequencies (TOFs) of 0.4–1.2 s⁻¹), and selectivity (> 95%) toward ethylene and propylene. The unique Pt nanolayer has a similar geometric surface to Pt nanoparticles, enabling the investigations of the electronic effect on the catalytic performance, where the geometric effect is negligible. It is found that the electronic effect plays a critical role in dehydrogenative product selectivity and catalyst stability. The metal–support interaction is found dependent on the substrate and metal components, providing wide opportunities to explore high-performance MXene-supported metallic catalysts.