Pd-Nanoparticles Embedded Metal–Organic Framework-Derived Hierarchical Porous Carbon Nanosheets as Efficient Electrocatalysts for Carbon Monoxide Oxidation in Different Electrolytes

Abstract

Rational synthesis of Co-ZIF-67 metal-organic framework (MOF)-derived carbon-supported metal nanoparticles is essential for various energy and environmental applications; however, their catalytic activity toward carbon monoxide (CO) oxidation in various electrolytes is not yet emphasized. Co-ZIF-67-derived hierarchical porous carbon nanosheet-supported Pd nanocrystals (Pd/ZIF-67/C) were prepared using a simple microwave-irradiation approach followed by carbonization and etching. Mechanistically, during microwave irradiation, triethyleneamine provides abundant reducing gases that promote the formation of Pd nanoparticles/Co-N_x in porous carbon nanosheets with the assistance of ethylene glycol and also form a multimodal pore size. The electrocatalytic CO oxidation activity and stability of Pd/ZIF-67/C outperformed those of commercial Pd/C and Pt/C catalysts by (4.2 and 4.4, 4.0 and 2.7, 3.59 and 2.7) times in 0.1 M HClO₄, 0.1 M KOH, and 0.1 M NaHCO₃, respectively, due to the catalytic properties of Pd besides the conductivity of Co-N_x active sites and delicate porous structures of ZIF-67. Notably, using Pd/ZIF-67/C results in a higher CO oxidation activity than Pd/C and Pt/C. This study may pave the way for using MOF-supported multi-metallic nanoparticles for CO oxidation electrocatalysis.