Enhancing energy storage and catalytic properties of bimetallic multifunctional MOFs by designing secondary-building units

With the development of wearable diagnostic devices, integrated bifunctional electrode materials with both electrochemical energy storage and glucose catalytic properties have attracted great attention. In order to obtain better electrochemical energy storage and glucose catalytic properties, in this paper, we reported a strategy to artificially intervene in the formation of extensible coordination structural units from metals and ligands (secondary-building units (SBUs)), in which the ligand of the monometallic MOFs was extended with Schiff base reaction to obtain new coordination sites and to form ultimate bimetallic MOFs with different SBUs by changing the metal feeding order. It is found that Ni-Co PyMOF, coordinated by Ni as a second metal with carboxyl-modified Co PyMOF, has the best electrochemical energy storage and catalytic properties due to its different SBUs with Co-Ni PyMOF and Ni/Co PyMOF. Ni-Co PyMOF exhibits a specific capacitance of 1471 C g⁻¹ at 1 A g⁻¹ and the asymmetric button-type supercapacitors with Ni-Co PyMOF exhibits the energy density of 37.43 W h kg⁻¹ with a power density of 850 W kg⁻¹ and the capacitance retention of 94 % after 5000 cycles. Besides, in the glucose catalytic properties test, Ni-Co PyMOF has a better properties with sensitivity of 387.63 μA cm⁻² mM⁻¹ in the linear range of 1.57 μM–3.50 mM. The experimental comparison reveals that Ni-Co PyMOF has higher energy storage capacity and glucose catalytic ability, which is a bifunctional MOF with promising applications.