Construction of Single-Cluster Rhodium Catalyst for Efficient CO₂ Hydrogenation to Ethanol

Area of Science:

• Catalysis
• Materials Science
• Chemical Engineering

Background:

• Thermocatalytic conversion of carbon dioxide (CO₂) to ethanol is crucial for CO₂ utilization.
• Controlling CO₂ activation and C-C coupling remains a significant challenge for high ethanol yields.

Purpose of the Study:

• To design a precise rhodium (Rh) single-cluster catalyst supported on carbon nitride (CN) for enhanced CO₂ hydrogenation to ethanol.
• To investigate the catalytic mechanism and identify factors contributing to high ethanol selectivity and yield.

Main Methods:

• Synthesis of a rhodium single-cluster catalyst on a carbon nitride support (Rh_SC/CN).
• Characterization using density functional theory (DFT) calculations, in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS), and X-ray absorption spectroscopy (XAS).
• Evaluation of catalytic performance under specific reaction conditions (240 °C, 5.0 MPa, H₂/CO₂ = 3).

Main Results:

• The Rh_SC/CN catalyst demonstrated a record turnover frequency (TOF_Rh) of 595.2 h^-1.
• Achieved high ethanol selectivity (95.3%) and yield (17.5 mmol g_cat^-1 h^-1).
• Synergistic interactions between Rh-Rh and Rh-N sites were identified as key to boosting CO₂ adsorption and C-C coupling.

Conclusions:

• The designed Rh_SC/CN single-cluster catalyst significantly improves CO₂ hydrogenation to ethanol.
• The study provides insights into catalyst design for simultaneous enhancement of CO₂ reactivity and ethanol selectivity.
• This work offers a promising strategy for efficient CO₂ utilization and sustainable chemical synthesis.