One-Pot Preparation\nof Nitro-Functionalized Bimetallic\nUiO-66(Zr-Hf) with Hierarchical Porosity for Oxidative Desulfurization\nPerformance

Preparation of multifunctional metal–organic frameworks\n(MOFs) offers new opportunities to obtain ultrahigh synergistic catalytic\nperformance for heterogeneous reactions; however, the application\nof a one-pot method for preparing multifunctional MOFs remains challenging.\nHerein, we develop a one-pot green route for synthesizing bimetallic\nnitro-functionalized UiO-66(Zr-Hf)-NO<sub>2</sub> with hierarchical\nporosity under solvent-free conditions. The optimal UiO-66(Zr-Hf<sub>0.6</sub>)-NO<sub>2</sub> shows an ultrahigh enhancement of oxidative\ndesulfurization (ODS) efficiency to oxidize sulfur compounds (1000\nppm sulfur) in a model fuel at 40 °C within 12 min due to the\nintroduction of more active Hf sites in the nodes, the increased Lewis\nacidity of Zr/Hf–O nodes by the electron-withdrawing NO<sub>2</sub> group, and the enhanced diffusion rates by the mesopores.\nThe turnover frequency (TOF) over UiO-66(Zr-Hf<sub>0.6</sub>)-NO<sub>2</sub> at 40 or 50 °C reaches 145.3 or 217.0 h<sup>–1</sup> that surpasses the TOF of most reported MOF-based catalysts in the\nODS reaction. Quenching and electron paramagnetic resonance experiments\nconfirm that the formed Hf–OH on the Zr/Hf–O nodes can\neasily decompose the oxidant (H<sub>2</sub>O<sub>2</sub>) for generating\na Hf-OOH-active intermediate and dominate the ODS efficiency. This\ncontribution provides a one-pot solvent-free avenue to synthesize\nmultifunctional MOFs for enhancing their catalytic activities for\ntargeted applications.