Construction of Single‐Cluster Rhodium Catalyst for Efficient CO ₂ Hydrogenation to Ethanol

Abstract

Abstract Thermocatalytic conversion of carbon dioxide (CO 2 ) into ethanol is a promising strategy for efficient utilization of CO 2 . However, it remains a grand challenge to achieve a high ethanol yield due to the difficulty in accurate control of CO 2 activation and C–C coupling under thermocatalytic reaction conditions. Herein, a precise rhodium (Rh) single‐cluster catalyst on carbon nitride support (Rh SC /CN) was designed for CO 2 hydrogenation to ethanol. The Rh SC /CN catalyst, with an average Rh–Rh coordination number of 2.06, exhibits a record turnover frequency (TOF Rh ) of 595.2 h −1 , a high ethanol selectivity of 95.3% and an ethanol yield of 17.5 mmol g cat −1  h −1 at 240 °C and 5.0 MPa (H 2 /CO 2  = 3), surpassing previously reported Rh‐based catalysts. Density functional theory calculations, in situ diffuse reflectance infrared Fourier transform spectroscopy, X‐ray absorption spectroscopy and H 2 /D 2 isotope exchange probing experiments altogether reveal the reaction mechanism, and show that the synergetic interaction between Rh–Rh and Rh–N sites boosts CO 2 adsorption and asymmetric C–C coupling between CH 3 * and CO* to form CH 3 CO*, leading to a high ethanol selectivity. This discovery provides new insights into the design of single‐cluster catalysts for simultaneously promoting CO 2 reactivity and ethanol selectivity.