Tuning of Ionic Second Coordination Sphere in Evolved Rhenium Catalyst for Efficient Visible-Light-Driven CO₂...

Area of Science:

• Photocatalysis
• Green Chemistry
• Materials Science

Background:

• Developing efficient catalysts for solar-driven carbon dioxide (CO2) reduction is crucial for sustainable energy solutions.
• Previous strategies often focused on CO2 absorption or anion dissociation, overlooking other critical catalyst properties.

Purpose of the Study:

• To design a novel rhenium (Re) catalyst with an ionic secondary coordination sphere for visible-light-induced CO2 photoreduction to CO.
• To identify key properties for effective catalyst design in CO2 reduction.

Main Methods:

• Synthesis and screening of a novel Re catalyst, {Re[BpyMe(tris(2-hydroxyethyl)amine)](CO)3 Cl}Br (Re-THEA).
• Investigation of catalyst performance using visible light for CO2 reduction.
• Density Functional Theory (DFT) calculations to elucidate reaction mechanisms and catalyst properties.

Main Results:

• The Re-THEA catalyst demonstrated a high quantum yield (up to 34%) for CO2 reduction to CO under visible light.
• The ionic tris(2-hydroxyethyl)amino (THEA) group was identified as crucial for enhancing visible-light absorption and stabilizing intermediates.
• The THEA group also effectively suppressed the formation of inactive Re-Re dimers.

Conclusions:

• Outstanding optical properties, rather than CO2 absorption, are a prerequisite for designing efficient photocatalysts for CO2 reduction.
• The Re-THEA catalyst represents a significant advancement in single-molecule systems for visible-light-driven CO2 conversion.
• This work provides a new strategy for designing advanced catalysts by incorporating ionic secondary coordination spheres.