K–FeCu/Multiwalled Carbon Nanotube with Hydrophobic Confinement and Multisites Synergy for Boosting CO ₂ Hydrogenation to Ethanol

CO 2 hydrogenation to ethanol is a promising pathway for carbon utilization, yet it remains challenged by the deactivation of iron-based catalysts due to water byproducts and the difficulty in controlling product selectivity. To address these issues, this work constructed hydrophobic MWCNT-supported K–FeCu bimetallic catalysts and systematically investigated their structure–activity relationships. The optimized catalyst (Fe/Cu = 0.5) exhibited superior performance at 320 °C and 4 MPa, achieving a CO 2 conversion of 41.1%, with ethanol selectivity and space-time yield (STY) reaching 28.91% and 175.91 mg·g cat –1 ·h –1, respectively. Mechanistic studies revealed that the intrinsic hydrophobicity of MWCNT facilitated water desorption to preserve the active Fe 5 C 2 phase. Synergistically, Cu promoted Fe reduction via hydrogen spillover, while K inhibited excessive hydrogenation, facilitating the C–C coupling of RWGS-derived CH x O* and CH x * intermediates at the interface. This study highlighted the importance of hydrophobic surface engineering, providing a strategy for designing catalysts for CO 2 hydrogenation to ethanol.