A hybrid borotungstate-coated metal–organic framework with supercapacitance, photocatalytic dye degradation and H2O2 sensing properties

Abstract

The compounding of polyoxometalates (POMs) with structurally well-defined and porous metal–organic frameworks (MOFs) has become a hot research topic. Here, a core–shell type hybrid, {Ag₅BW₁₂O₄₀}@[Ag₃(μ-Hbtc)(μ-H₂btc)]_n (called {Ag₅BW₁₂O₄₀}@Ag-BTC-2, where BTC = 1,3,5-benzyl carboxylic acid), was successfully prepared via a simple grinding method. IR, XRD, SEM, TEM, and XPS analysis was used to confirm the structure. The specific capacitance is 179.1 F g⁻¹ when the current density is 1 A g⁻¹, using nickel foam as the collector, and the capacitance retention is 97.4% after 5000 cycles. The resulting aqueous-based symmetric supercapacitor has a power density of 496 W kg⁻¹ and an energy density of 12.4 W h kg⁻¹. In addition, the degradation rates using {Ag₅BW₁₂O₄₀}@Ag-BTC-2 toward methylene blue (MB), rhodamine B (RhB), and methyl orange (MO) exceeded 90% in 140 min and remained essentially unchanged over five replicate experiments, showing high photocatalytic activity. Meanwhile, when {Ag₅BW₁₂O₄₀}@Ag-BTC-2 acts as a H₂O₂ biosensor, it has a low detection limit (0.19 μM), a wide linear range (0.4 μM–0.27 mM) and high anti-interference properties. This shows that the synthesis of POMOFs via a grinding method is an effective strategy to improve the performance.