A novel core-shell structured hybrid composed of zinc homobenzotrizoate and silver borotungstate with supercapacitor and photocatalytic dye degradation performance

Abstract

Polyoxometalate-based metal-organic frameworks (POMOFs) are challenging as electrode materials for supercapacitors and catalysts for the photocatalytic degradation of organic pollutants. To this end, a novel core-shell structured zinc homobenzotrizoate and silver borotungstate ([Zn4(BTC)2(μ4-O)(H2O)2]@Ag5[BW12O40], abbreviated as Zn-BTC@Ag5[BW12O40], BTC = 1,3,5-benzylcarboxylic acid) was synthesized by wrapping polyoxometalate (POM) on metal-organic framework (MOF) by a simple grinding method. This unique synergy between the core (Zn-BTC) and shell (Ag5[BW12O40]) sets the compound more surface active sites. The composition, structure, and morphology of the title compound were discussed by infrared (IR), powder X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and other methods. In the three-electrode foam nickel system, the Zn-BTC@Ag5[BW12O40] electrode showed a higher specific capacitance (161.7 F g−1) than the Ag5[BW12O40] (97.7 F g−1) and Zn-BTC (118.4 F g−1), and the capacitance retention rate was 92.8% after 5000 cycles. Assembled into a symmetrical supercapacitor with an energy density of 9.3 Wh Kg−1 and a power density of 501.2 W Kg−1. The capacitance retention rate reached 91.4% after 5000 cycles. In addition, The photocatalytic degradation efficiency of Zn-BTC@Ag5[BW12O40] for Methylene Blue (MB), Methyl Orange (MO), and Rhodamine B (RhB) dyes are all greater than 90% in 140 min. The photocatalytic cycle test has been carried out 5 times, and the degradation effect remains the same. This indicates that the title compound has high activity in the direction of photocatalytic degradation of dyes.