Precise Dual-Metal Pairs Enable Ultrafast Structural Response for CO₂-to-Ethylene Photoconversion.

Area of Science:

• Catalysis
• Materials Science
• Photochemistry

Background:

• Dual-metal sites offer synergistic effects for catalysis but suffer from random distribution and undefined coordination environments, hindering mechanistic studies.
• Investigating charge transfer dynamics and catalytic mechanisms at the atomic level is crucial for designing efficient catalysts.

Purpose of the Study:

• To develop a precise strategy for constructing well-defined dual-metal sites within metal-organic frameworks (MOFs).
• To elucidate the charge transfer dynamics and catalytic mechanisms for carbon dioxide (CO2) photoreduction to ethylene.

Main Methods:

• Anchoring single atoms (Cu) into vacancy-rich MOFs (Mil-125(Ti)-NH2) to form precisely distributed dual-metal pairs.
• Utilizing low-dose real-space imaging and X-ray absorption spectra to characterize the dual-metal sites and charge transfer.
• Performing mechanistic investigations including intermediate analysis and structural self-regulation studies.

Main Results:

• Successfully constructed well-defined Cu-Ti dual-metal pairs in oxygen vacancy-rich MOFs.
• Observed rapid charge transfer from Ti to Cu within 3.0 ps, confirmed by advanced characterization techniques.
• Achieved a high solar-to-chemical efficiency of 0.62% and an electron-based selectivity of 78.3% for ethylene production from CO2 and H2O.
• Demonstrated the generality of this strategy for other MOF-based catalysts.

Conclusions:

• Precisely engineered dual-metal sites in MOFs provide a viable strategy for efficient CO2 photoreduction to ethylene.
• The identified Cu-Ti bimetallic pairs facilitate C-C coupling through strong d-p hybridization and structural self-regulation.
• This work bridges the gap between experimental observations and theoretical insights in dual-metal catalysis.