Engineering N-Co3O4 support to stabilize active Pd structures for methane combustion with enhanced activity and water resistance

Defect engineering in oxide supports has emerged as a promising approach to enhance the surface chemical properties of active metals for methane catalytic oxidation. Herein, the N-doped Pd/Co 3 O 4 (Pd/N-Co 3 O 4 ) catalysts were successfully synthesized using ZIF-67 as a self-sacrificial template via an H 2 O-soaking treatment. Compared to conventional Pd/Co 3 O 4 catalysts (T 50 : 294 °C), the Pd/N-Co 3 O 4 catalysts exhibited superior catalytic activity (T 50 : 278 °C) and exceptional water resistance, with only a 6% activity loss at 350 °C in the presence of 5   vol% H 2 O, as opposed to a 56% loss for Pd/Co 3 O 4 catalysts. Detailed experimental characterizations revealed that N-doping significantly increased oxygen vacancy concentrations and surface lattice oxygen mobility while stabilizing Pd/PdO x active sites through the electronic metal-support interaction (EMSI) between Pd and N-Co 3 O 4 . In the Pd/N-Co 3 O 4 catalysts, the enhanced oxygen vacancies rendered the N-Co 3 O 4 support electron-rich, which in turn diminishes the electron transfer from Pd to N-Co 3 O 4 supports. This modulation effectively inhibited the excessive oxidation of Pd/PdO x active species into bulk PdO, thereby enhancing catalytic performance and water tolerance in methane oxidation. These findings provide valuable insights into the role of N-doped defect engineering in facilitating efficient methane catalytic combustion, highlighting the significance of EMSI and oxygen vacancies in optimizing catalyst performance.