Defect-Driven Efficient Selective CO₂ Hydrogenation with Mo-Based Clusters

Area of Science:

• Catalysis
• Materials Science
• Climate Change Mitigation

Background:

• Synthetic fuels from CO₂ offer a sustainable alternative to fossil fuels.
• The reverse water gas shift (RWGS) reaction is crucial for CO₂ utilization.
• Molybdenum-based catalysts show promise for RWGS due to stability.

Purpose of the Study:

• To identify the origin of high activity in Mo₂C catalysts for CO₂ hydrogenation.
• To investigate the role of defects in Mo₂C catalysts.
• To develop highly active and selective catalysts for CO₂ conversion.

Main Methods:

• Synthesis of defected Mo₂C clusters supported on nitrogen-doped graphene.
• Characterization of catalyst structure and properties.
• Evaluation of catalytic performance in CO₂ hydrogenation (RWGS reaction).

Main Results:

• Defected Mo₂C clusters exhibited exceptional catalytic performance (6.3 g_CO/g_cat/h at 400 °C) with >99% CO selectivity.
• Mo defects were identified as the intrinsic origin of high catalytic activity.
• Catalyst demonstrated superior performance compared to other Mo-based and noble metal catalysts.
• Atomic magnetism correlated with CO liberation capacity; defects reduced magnetization.
• Defects neutralized negative charges on surface hydrogen, aiding selective hydrogenation.

Conclusions:

• Defected Mo₂C clusters on nitrogen-doped graphene are highly effective for CO₂-selective hydrogenation.
• Mo defects play a critical role in enhancing catalytic activity and selectivity.
• Carbon support and carbonization are effective strategies for creating Mo defects, with biochar as a cost-effective option for scalability.