Defect-rich carbon induced built-in electric fields within molybdenum-based metal-organic framework catalysts for...

Metal-organic frameworks have attracted significant interest in catalysis because of their exceptional performance. However, metal-organic frameworks encounter the challenge of balancing activity with stability in oxidative desulfurization (ODS). Herein, we designed a defect-rich carbon nanosheet (D-CN)-supported molybdenum-based metal-organic framework (Mo-MOF) catalyst (Mo-MOF/D-CN) to enhance the activity and stability for ODS by constructing a strong built-in electric field. Theoretical and experimental results indicated that a strong built-in electric field was formed in the direction from D-CN to Mo-MOF due to the regulation of defects to the work function of the carbon support. This built-in electric field optimized the electronic structure of Mo-MOF, altering the activation pathway of hydrogen peroxide and thereby promoting the efficient generation of superoxide radical and singlet oxygen. Additionally, the built-in electric field strengthened the strong attraction and the van der Waals interaction at the interface of Mo-MOF/D-CN, effectively preventing the leaching of active Mo species. Thus, Mo-MOF/D-CN exhibited markedly enhanced catalytic activity and stability for dibenzothiophene oxidation compared to the Mo-MOF without built-in electric field. Its turnover frequency was increased by 24.5 times to 120.1 h^-1, while the leaching rate of Mo species was decreased by 86.3 %. Notably, the resulting Mo-MOF/D-CN catalyst demonstrated exceptional catalytic performance in ODS of real diesels, achieving complete removal of thiophenic sulfides in 60 min with an oxidant consumption (O/S = 3) lower than the currently reported value. The strategy effectively overcomes the activity-stability trade-off commonly encountered with metal-organic frameworks.