Selective Solar CO₂ Conversion into Ethanol Using Atomic-Scale Copper Clusters Anchored π-extended Poly(heptazine...

Area of Science:

• Materials Science
• Catalysis
• Renewable Energy

Background:

• Photocatalytic reduction of carbon dioxide (CO2) to C1 products is established, but selective conversion to C2 products like ethanol remains challenging.
• Achieving C2 selectivity requires precise control over proton-coupled electron transfer and C-C coupling kinetics over competing reaction pathways.

Purpose of the Study:

• To develop a catalyst for selective photocatalytic CO2 reduction to C2 products, specifically ethanol.
• To investigate the role of atomic-scale copper (Cu) clusters and carbon doping in enhancing CO2 conversion efficiency and selectivity.

Main Methods:

• Synthesis of atomic-scale copper (Cu) clusters anchored on carbon-doped potassium poly(heptazine imide) (Cu/C-K-PHI).
• Characterization of the catalyst's electronic and optical properties, including narrowed bandgap and suppressed charge-carrier recombination.
• In situ spectroscopy and density functional theory (DFT) calculations to elucidate the reaction mechanism.

Main Results:

• Cu/C-K-PHI demonstrated high selectivity (∼100%) for ethanol production in liquid phase.
• Achieved a CO2 reduction rate of 18.98 µmol g⁻¹ h⁻¹, reaching 77.01 µmol g⁻¹ after 4 hours.
• Catalyst retained ∼98% activity over five cycles, operating under 1-sun illumination without sacrificial agents.
• Solar-to-ethanol conversion efficiency reached 0.175% with an apparent quantum yield of 0.516%.

Conclusions:

• Synergistic effects of electronic structure modulation and atomic-scale metal engineering enable selective CO2 photoreduction to ethanol.
• The O*C─CO-mediated *CO dimerization pathway is identified as key to achieving high ethanol selectivity.
• This work presents a viable strategy for efficient and selective solar fuel production from CO2 under mild conditions.