Lattice Oxygen-Mediated Electrochemical Carbon Dioxide Reduction

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• The precise role of lattice oxygen and hydroxyl groups in CO2 electroreduction (CO2RR) remains unclear.
• Determining active participation of lattice oxygen species in CO2RR is a critical challenge.

Purpose of the Study:

• To investigate the involvement of lattice oxygen atoms in CO2RR using Sn3O2(OH)2 as a model catalyst.
• To elucidate the mechanism of formate electrosynthesis mediated by lattice oxygen.

Main Methods:

• Operando 17O nuclear magnetic resonance (NMR) spectroscopy with isotopically labeled catalysts.
• Density functional theory (DFT) calculations.
• Operando X-ray absorption fine structure (XAFS) and X-ray diffraction (XRD) analyses.

Main Results:

• Direct experimental evidence confirmed formate originates from lattice oxygen via the lattice oxygen mechanism (LOM).
• DFT calculations supported the feasibility of the LOM pathway, distinct from adsorbate evolution mechanisms.
• Sn3O2(OH)2 structure stabilization by C2O4(2-) ligands was observed through XAFS and XRD.

Conclusions:

• Lattice oxygen atoms actively participate in CO2RR, enabling formate electrosynthesis via a novel LOM.
• Findings offer new mechanistic insights and design principles for advanced oxide catalysts in CO2RR.
• The study highlights the potential of lattice oxygen participation for developing highly active and stable CO2RR catalysts.