Contiguous Mo Species and SMSI Effect in MoO Reinforce Catalytic Performance in Reverse Water-Gas Shift Reaction.

Area of Science:

• Catalysis
• Materials Science
• Chemical Engineering

Background:

• The reverse water-gas shift (RWGS) reaction is key for CO2 valorization but requires high-temperature, durable catalysts.
• Endothermic nature of RWGS necessitates catalysts with excellent thermal stability and activity.

Purpose of the Study:

• To investigate the dynamic structural changes of platinum-loaded molybdenum suboxide (Pt/MoOx) catalysts during the RWGS reaction.
• To elucidate the mechanism behind the catalyst's high performance and stability at elevated temperatures.

Main Methods:

• Utilized multiple *operando* and *in situ* measurements, including X-ray absorption fine structure (XAFS).
• Analyzed dynamic structural evolution and electronic properties of the catalyst under reaction conditions.

Main Results:

• Pt/MoOx catalysts demonstrated high activity, CO selectivity, and stability at 500 °C.
• Emergence of contiguous Mo species (Mo--Mo) and strong metal-support interaction (SMSI) were crucial for performance.
• Reversible redox of *in situ*-formed MoOx suboxide and suppressed CO adsorption by MoOx shell contributed to high CO selectivity.

Conclusions:

• The RWGS reaction mechanism involves reversible redox of MoOx suboxide, with Mo--Mo species activating CO2.
• Catalyst stability is enhanced by SMSI and MoOx shell preventing CO poisoning.
• Partial carburization of MoOx increases catalytic activity and electron density, improving performance over time.