An inorganic–organic hybrid nanomaterial with a core–shell structure constructed by using Mn–BTC and Ag5[BW12O40] for supercapacitors and photocatalytic dye degradation

Abstract

Creating inorganic–organic hybrids with polyoxometalates (POMs) and metal–organic frameworks (MOFs) as energy storage and dye-degradation materials remains challenging. Here, a new hybrid nanomaterial Mn–BTC@Ag₅[BW₁₂O₄₀] is synthesized by using Ag₅[BW₁₂O₄₀] and Mn₃(BTC)₂(H₂O)₆ (Mn–BTC, BTC = 1,3,5-benzenetricarboxylic acid) through a plain grinding method. The structure and morphology characterization by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and transmission electron microscopy (TEM) shows that the synthetic products have core–shell construction. Due to its unique structure wherein the core is Mn–BTC and the shell is Ag₅[BW₁₂O₄₀], it exhibits excellent capacitance performance. In a three-electrode system where nickel foam is a collector, at a current density of 1 A g⁻¹, its specific capacitance is 198.09 F g⁻¹; after 5000 cycles, the capacitance retention rate is 94.4%. When the power density is 503.1 W kg⁻¹, the symmetrical supercapacitor reveals a high energy density which is 10.9 W h kg⁻¹. At the same time, the capacitance retention is 92.9% after 5000 cycles which showed good cycle stability. The photocatalytic degradation efficiencies of rhodamine B (RhB), methyl orange (MO) and methylene blue (MB) dyes exceed 90% after 140 min, and the degradation results remained unchanged after five photocatalytic cycles. The photocatalytic degradation mechanism shows that ˙OH has a major effect. The results show that this research provides a fresh idea for the development of energy storage and dye photocatalytic degradation materials.