Polymorph selection towards photocatalytic gaseous CO₂ hydrogenation

Area of Science:

• Materials Science
• Catalysis
• Photochemistry

Background:

• Polymorphism in materials engineering is key to optimizing photocatalyst performance.
• Titanium dioxide (anatase and rutile) is known for gas-phase CO2 photocatalysis.
• Indium sesquioxide (cubic polymorph) is a documented CO2 hydrogenation photocatalyst.

Purpose of the Study:

• To investigate the photocatalytic activity of the rhombohedral polymorph of indium sesquioxide for CO2 hydrogenation.
• To compare the performance of the rhombohedral polymorph with its cubic counterpart.
• To understand the origin of performance differences in indium sesquioxide polymorphs.

Main Methods:

• Synthesis and characterization of rhombohedral indium sesquioxide.
• Photocatalytic CO2 hydrogenation experiments under controlled conditions.
• Analysis of reaction products (CH3OH and CO) and catalyst stability.

Main Results:

• The rhombohedral polymorph of indium sesquioxide demonstrated photocatalytic activity for CO2 hydrogenation.
• It produced both methanol (CH3OH) and carbon monoxide (CO).
• The rhombohedral form exhibited higher activity, superior stability, and improved selectivity towards CH3OH over CO compared to the cubic form.

Conclusions:

• The rhombohedral polymorph of indium sesquioxide is an effective photocatalyst for CO2 hydrogenation.
• Enhanced surface acidity and basicity of frustrated Lewis pairs in the rhombohedral form contribute to its superior performance.
• This finding highlights the potential of exploring less common polymorphs for advanced catalytic applications.