Carbon-Aerogel-Confined MoO₂ as a Robust Nanocatalyst for the Reverse Water-Gas Shift Reaction

Area of Science:

• Catalysis
• Materials Science
• Chemical Engineering

Background:

• The reverse water-gas shift (RWGS) reaction is crucial for carbon cycling, converting CO₂ into valuable syngas.
• Developing efficient, non-noble metal catalysts is key for industrial RWGS applications.
• Molybdenum carbide (Mo₂C) is often considered the active species, formed from MoO_x precursors.

Purpose of the Study:

• To investigate the catalytic activity and stability of MoO₂ for the RWGS reaction.
• To explore the effect of interfacial confinement on MoO₂ stability under reaction conditions.
• To challenge the prevailing view of MoO_x as solely a precursor to carbides.

Main Methods:

• Synthesis of MoO₂ nanoparticles confined within a carbon aerogel matrix.
• Characterization of the catalyst's structure and composition before and after reaction.
• Testing the catalyst's performance and stability in the RWGS reaction at elevated temperatures.

Main Results:

• Confined MoO₂ demonstrated intrinsic activity and stability as an RWGS catalyst.
• Interface confinement effectively prevented over-reduction and carburization of MoO₂ at 500 °C for 200 h.
• Unconfined MoO₂ nanoparticles transformed into metallic Mo under identical conditions.

Conclusions:

• MoO₂ can be an intrinsically active and stable RWGS catalyst when stabilized by interfacial confinement.
• Interfacial confinement plays a critical role in preventing catalyst degradation, differing from the typical MoO_x to Mo₂C transformation pathway.
• This work highlights the importance of catalyst support interactions in designing robust nanocatalysts for high-temperature reactions.