Graphitic Armor: A Natural Molecular Sieve for Robust Hydrogen Electroxidation.

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• Carbon coating layers enhance transition metal catalyst performance, often attributed to electronic synergy.
• Robust catalysts are needed for hydrogen-relevant processes, particularly those resistant to poisoning.

Purpose of the Study:

• To investigate the role of defective graphitic carbon as a molecular sieve in catalysis.
• To elucidate the mechanism by which carbon layers protect metal catalysts from poisons.

Main Methods:

• Characterization of defective graphitic carbon with a specific interlayer gap (0.342 nm).
• Analysis of diffusion properties for hydrogen, CO, and O2 through the carbon layer.
• Evaluation of catalyst performance and poisoning tolerance in hydrogen-relevant reactions.

Main Results:

• Defective graphitic carbon functions as a selective molecular sieve due to its 0.342 nm interlayer gap.
• The sieve allows efficient hydrogen diffusion but sterically hinders larger molecules like CO and O2.
• Poisonous species larger than 0.342 nm are excluded, preserving metal-hydrogen interactions and catalyst activity.

Conclusions:

• Defective graphitic carbon acts as a natural molecular sieve, offering a novel protection mechanism for catalysts.
• This sieving effect enhances catalyst robustness against oxidation and CO-poisoning in hydrogen-based applications.
• The findings provide a new strategy for designing durable and selective metal catalysts.