A Robust Carbon Overlayer as Hydrogen Spillover Highway and CO-Binding Barrier Enhances Reverse Water-Gas Shift

Area of Science:

• Catalysis
• Materials Science
• Environmental Chemistry

Background:

• Selective CO2 hydrogenation to CO via the reverse water-gas shift (RWGS) reaction is crucial for carbon abatement but limited by catalyst efficiency and scalability.
• Existing catalysts face challenges with activity-selectivity trade-offs and undesirable side reactions like methanation.

Purpose of the Study:

• To develop a high-performance Ni/TiO2 catalyst encapsulated in a carbon layer for enhanced CO2 conversion and CO selectivity in RWGS reactions.
• To elucidate the mechanism behind the carbon layer's function in boosting catalytic performance and mitigating side reactions.

Main Methods:

• In situ creation of a robust carbon layer encapsulating Ni/TiO2 nanoparticles.
• Mechanistic studies employing an oxygen-vacancy-mediated redox pathway.
• Evaluation of catalyst performance under industrially relevant conditions for CO2 conversion and CO selectivity.

Main Results:

• The carbon-coated Ni/TiO2 catalyst demonstrated boosted CO2 conversion and near-100% CO selectivity, reaching equilibrium conversion.
• The carbon overlayer facilitated hydrogen spillover, generating distal oxygen vacancies on TiO2 for efficient CO2 dissociation.
• The catalyst suppressed methanation and CO disproportionation by inhibiting CO adsorption on Ni, maintaining performance for over 500 hours.

Conclusions:

• Encapsulating Ni/TiO2 with a carbon layer provides a dual function, enhancing CO2 activation and suppressing CO adsorption, thereby overcoming the activity-selectivity trade-off in RWGS catalysis.
• This approach offers a scalable and economical strategy for designing advanced hydrogenation catalysts for carbon capture and utilization.
• The developed catalyst significantly outperforms existing catalysts, showing great promise for industrial carbon abatement applications.