A hybrid borotungstate-coated metal-organic framework with supercapacitance, photocatalytic dye degradation and H 2 O 2 sensing properties.

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, {Ag 5 BW 12 O 40 }@[Ag 3 (μ-Hbtc)(μ-H 2 btc)] n (called {Ag 5 BW 12 O 40 }@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 {Ag 5 BW 12 O 40 }@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 {Ag 5 BW 12 O 40 }@Ag-BTC-2 acts as a H 2 O 2 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.