Oxidative desulfurization (ODS) is a promising strategy for the removal of sulfur compounds from fuel because of its mild conditions and high selectivity. Furthermore, its efficiency may be notably improved through the precise regulation of the microenvironment surrounding the catalytically active sites. In this work, a series of monosubstituted Keggin polyoxometalates incorporating different transition metals (Fe, Co, Ni) were designed and immobilized on the surface of hexagonal boron nitride (h-BN) using ionic liquids ([C₄mim]BF₄), affording novel supported catalysts for ODS. The Ni-substituted catalyst (PW₁₁Ni-C₄/BN) exhibited high activity and excellent recyclability, which was attributed to the specific electronic structure of the W=O active centers and the strong adsorption capability of the h-BN support. Under optimal conditions (catalyst dosage: 20 mg, O/S ratio: 3, temperature: 60 °C, sulfur content: 500 ppm dibenzothiophene (DBT) in n-octane), sulfur was completely removed within 40 min. In addition, mechanistic studies revealed that hydroxyl radicals (·OH) and superoxide radicals (·O₂⁻) collaboratively drive the catalytic reaction.

Four new metal–organic frameworks ([Ag₃(dpdo)_3.5(DMF)(PW₁₂O₄₀)]∙H₂O (1), [Ag₃(dpdo)₅(DMF)₂(PW₁₂O₄₀)]∙2CH₃OH (2), [Ag₃(dpdo)₅(DMF)₂(PMo₁₂O₄₀)]∙4H₂O (3), and H_0.5[Ag_4.5(dpdo)₅(DMF)(BW₁₂O₄₀)]∙5H₂O (4); dpdo = 4,4'-dipyridine-N,N'-dioxide) based on polyoxometalates were created, and their properties were examined using infrared (IR) spectroscopy, powder X-ray diffraction, elemental analysis, and comprehensive single-crystal structure investigations. In compounds 1 and 4, the secondary building blocks ([Ag₆O₂₀] and [Ag₃O₁₄] for 1 and 4, respectively) serve as nodes that connect the dpdo ligands with the polyanions ([PW₁₂O₄₀]³⁻ and [BW₁₂O₄₀]⁵⁻ for 1 and 4, respectively) to create a three-dimensional (3D) framework. By joining Ag ions and dpdo ligands and enclosing the polyanions ([PW₁₂O₄₀]³⁻ and [PMo₁₂O₄₀]³⁻ for compounds 2 and 3, respectively) as templates and counterions, compounds 2 and 3 display a two-dimensional (2D) gridlike network. Additionally, the solid state optical, luminescent, and ultraviolet–visible (UV–vis) spectral features of compounds 1–4 as well as the electrochemical characteristics of compounds 1–3 were examined.