Fine-tuning of ultrathin carbon shells coated on metal nanoparticles: carbon etching and defect healing effects

Carbon-incorporated metal nanoparticles are heat-treated in various gas atmospheres to create carbon shells with different porosity. A highly porous carbon shell is formed due to the carbon etching effect by H-2, and the defect healing effect by CO is discovered through additional CO gas treatment of the H-2/N-2 gas-treated sample.