Efficient Surface to Bulk Catalysis in the Reverse Water-Gas Shift Reaction by the FeO_x/Fe₃C Catalyst

Area of Science:

• Heterogeneous catalysis
• Surface science
• Materials chemistry

Background:

• Understanding catalyst mechanisms is crucial for advancing chemical reactions.
• The reverse water-gas shift (RWGS) reaction is vital for CO2 utilization.
• Iron-based catalysts show promise for RWGS but require mechanistic elucidation.

Purpose of the Study:

• To investigate the dynamic structural evolution and reaction mechanisms of catalysts.
• To identify the active phase in iron-based RWGS catalysis.
• To elucidate the surface-to-bulk atom transfer mechanism.

Main Methods:

• In situ characterization of catalyst structure and dynamics.
• Mechanistic studies of CO2 dissociation and carbon infiltration.
• Kinetic analysis of the RWGS reaction over the FeO𝑥/Fe₃C heterostructure.

Main Results:

• An in situ dynamic FeO𝑥/Fe₃C heterostructure was identified as the active phase.
• CO2 dissociation on FeO𝑥 and carbon infiltration into Fe₃C were observed.
• A synergistic surface-to-bulk cycling mechanism involving carbon and oxygen transfer was revealed.

Conclusions:

• The FeO𝑥/Fe₃C heterostructure enables rapid atom exchange via a dynamic surface-to-bulk mechanism.
• This mechanism leads to unprecedented catalytic activity for the RWGS reaction.
• The study provides new insights into the origin of high activity in iron-based catalysts.