CO₂ reduction with protons and electrons at a boron-based reaction center

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Sustainable Energy

Background:

• Borohydrides are vital reducing agents with potential in hydrogen storage and CO2 reduction.
• Current synthesis methods for borohydrides are energy-intensive and costly, limiting their widespread application.
• Direct synthesis from reduced boron compounds offers a promising alternative to overcome these limitations.

Purpose of the Study:

• To explore the direct synthesis of borohydrides via protonation of reduced boron compounds.
• To investigate the CO2 reduction capabilities of novel gold-borane complexes.
• To establish a synthetic cycle for CO2 reduction utilizing boron-based chemistry.

Main Methods:

• Synthesis and characterization of the redox series [Au(B2P2)]n (n = +1, 0, -1).
• Protonation reactions to form mono- and diborohydride complexes.
• Electrochemical studies and reactions with CO2 to elucidate reaction pathways.

Main Results:

• The monoborohydride complex was successfully synthesized via protonation of [Au(B2P2)]- at mild potentials.
• [Au(B2P2)]- reduces CO2 to a formate complex, which can be further cleaved.
• Direct reaction of [Au(B2P2)]- with CO2 leads to CO release and carbonate formation, demonstrating a CO2 reduction cycle.

Conclusions:

• A novel synthetic route to borohydrides is established, bypassing energy-intensive alkali metal processes.
• The developed gold-borane complexes show promise for efficient CO2 reduction and conversion.
• This work presents a viable boron-based catalytic cycle for CO2 utilization in energy applications.