Ultrathin Co3O4 Layers Realizing Optimized CO2 Electroreduction to Formate

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• The electroreduction of carbon dioxide (CO2) into hydrocarbons is a promising strategy for mitigating the energy crisis and global warming.
• Conventional electrocatalysts often exhibit limitations in energetic efficiency and long-term durability, hindering practical applications.
• Transition-metal oxides present potential as electrocatalysts, but their performance is often constrained by surface area and conductivity.

Purpose of the Study:

• To investigate the potential of atomic layers of transition-metal oxides as advanced electrocatalysts for CO2 reduction.
• To address the challenges of low energetic efficiency and poor durability associated with traditional electrocatalysts.
• To explore the structure-activity relationship in ultrathin metal oxide films for enhanced CO2 electroreduction.

Main Methods:

• Synthesis of ultrathin cobalt oxide (Co3O4) layers with atomic thickness (1.72 nm and 3.51 nm) using a fast-heating strategy.
• Characterization of the synthesized Co3O4 layers to determine their atomic thickness, active site density, and electronic properties.
• Electrochemical evaluation of the Co3O4 layers for CO2 electroreduction, measuring catalytic activity and Faradaic efficiency.

Main Results:

• Atomic thickness of Co3O4 layers provides an ultralarge fraction of active sites and enhances CO2 adsorption.
• Ultrathin Co3O4 layers exhibit improved electronic conductivity due to increased and more dispersed charge density near the Fermi level.
• The 1.72 nm thick Co3O4 layers demonstrated significantly higher electrocatalytic activity (1.5x and 20x) compared to thicker layers and bulk Co3O4.
• The 1.72 nm Co3O4 layers achieved a formate Faradaic efficiency exceeding 60% over a 20-hour period.

Conclusions:

• Atomic layer engineering of transition-metal oxides, exemplified by ultrathin Co3O4, is a viable strategy to enhance CO2 electroreduction.
• The superior performance is attributed to the increased active sites, improved conductivity, and structural stability of the atomic layers.
• These findings offer a pathway towards developing highly efficient and durable electrocatalysts for sustainable CO2 conversion.