Lewis acidic Fe-driven catalytic active Ni formation in Fe-free metal-organic framework for enhanced electrochemical glucose sensing.

Manipulating metal valence states and porosity in the metal-organic framework (MOF) by alloying has been a unique tool for creating high-valent metal sites and pore environments in a structure that are inaccessible by other methods, favorable for accelerating the catalytic activity towards sensing applications. Herein, we report Fe-driven formation of catalytic active Ni species in the amine-crafted benzene-dicarboxylate (BDC-NH)-based MOF as a high-performance electrocatalyst for glucose sensing. This work took the benefit of different bonding stability between BDC-NH ligand, and Fe and Ni metal precursor ions in the heterometallic NiFe-BDC-NH MOF. The FeCl that interacts weakly with ligand, oxidizes the Ni precursor to Ni-based MOF owing to its Lewis acidic behavior and was subsequently removed from the structure supported by Ni atoms, during solvothermal synthesis. This enables to create mesopores within a highly stable Ni-MOF structure with optimal feed composition of NiFe-BDC-NH. The Ni-based NiFe-BDC-NH demonstrates superior catalytic properties towards glucose sensing with a high sensitivity of 13,435 µA mM cm compared to the parent Ni-based Ni-BDC-NH (10897 μA mMcm), along with low detection limit (0.9 μM), short response time (≤5 s), excellent selectivity, and higher stability. This presented approach for fabricating high-valent nickel species, with a controlled quantity of Fe integrated into the structure allowing pore engineering of MOFs, opens new avenues for designing high-performing MOF catalysts with porous framework for sensing applications.