In Situ Implanting of Single Tungsten Sites into Defective UiO‐66(Zr) by Solvent‐Free Route for Efficient Oxidative Desulfurization at Room Temperature

Heterogeneous activation of self-generated H2O2 by Pd@UiO-66(Zr) for trimethoprim degradation: Efficiency and mechanism

The Fenton reaction is recognized as an effective technique for degrading persistent organic pollutants, such as the emerging pollutant trimethoprim (TMP). Recently, due to the excellent reducibility of active hydrogen ([H]), Pd-H2 has been preferred for Fenton-like reactions and the specific H2 activation of Pd-based catalysts. Herein, a heterogeneous Fenton catalyst named the hydrogen-accelerated oxygen reduction Fenton (MHORF@UiO-66(Zr)) system was prepared through the strategy of building ships in the bottle. The [H] has been used for the acceleration of the reduction of Fe(III) and self-generate H2O2. The systematic characterization demonstrated that the nano Pd0 particle was highly dispersed into the UiO-66(Zr). The results found that 20 mg L-1 of TMP was thoroughly degraded within 90 min in the MHORF@UiO-66(Zr) system under conditions of initial pH 3, 30 mL min-1 H2, 2 g L-1 Pd@UiO-66(Zr) and 25 μM Fe2+. The hydroxyl radical as well as the singlet oxygen were evidenced to be the main reactive oxygen species by scavenging experiments and electron spin resonance. In addition, both reducing Fe(III) and self-generating H2O2 could be achieved due to the strong metal-support interaction (SMSI) between the nano Pd0 particles and UiO-66(Zr) confirmed by the correlation results of XPS and calculation of density functional theory. Finally, the working mechanism of the MHORF@UiO-66(Zr) system and the possible degradation pathway of the TMP have been proposed. The novel system exhibited excellent reusability and stability after six cyclic reaction processes.

Mechanically Enhanced Detoxification of Chemical Warfare Agent Simulants by a Two-Dimensional Piezoresponsive Metal-Organic Framework

Chemical warfare agents (CWAs) refer to toxic chemical substances used in warfare. Recently, CWAs have been a critical threat for public safety due to their high toxicity. Metal-organic frameworks have exhibited great potential in protecting against CWAs due to their high crystallinity, stable structure, large specific surface area, high porosity, and adjustable structure. However, the metal clusters of most reported MOFs might be highly consumed when applied in CWA hydrolysis. Herein, we fabricated a two-dimensional piezoresponsive UiO-66-F4 and subjected it to CWA simulant dimethyl-4-nitrophenyl phosphate (DMNP) detoxification under sonic conditions. The results show that sonication can effectively enhance the removal performance under optimal conditions; the reaction rate constant k was upgraded 45% by sonication. Moreover, the first-principle calculation revealed that the band gap could be further widened with the application of mechanical stress, which was beneficial for the generation of 1O2, thus further upgrading the detoxification performance toward DMNP. This work demonstrated that mechanical vibration could be introduced to CWA protection, but promising applications are rarely reported.

Defective silicotungstic acid-loaded magnetic floral N-doped carbon microspheres for ultra-fast oxidative desulfurization of high sulfur liquid fuels

Highly active Keggin-type silicotungstic acid (SiW12) with oxygen vacancy (Ov) defects was encapsulated into the magnetic floral N-doped carbon microspheres (γ-Fe2O3@NC-300) through the facile one-step air pyrolysis of the precursor comprising core-shell Fe3O4@polydopamine (Fe3O4@PDA) and SiW12 to prepare γ-Fe2O3@NC@SiW12-300. The fabricated catalysts were systematically characterized and subsequently employed for the oxidation desulfurization (ODS) of the model fuel. The magnetic floral γ-Fe2O3@NC@SiW12-300 catalyst exhibited nearly perfect catalytic activity, which under mild conditions could remove 100% amount of 4000 ppm DBT in model fuel within 20 min (0.03 g catalysts and n(H2O2)/n(S) of 2). The catalyst activity is mainly attributed to the high activity SiW12 with the Ov defect and its outstanding dispersibility in γ-Fe2O3@NC, along with the high number of exposed active sites. A selected catalyst, γ-Fe2O3@NC@SiW12-300, showed a noticeable turnover frequency (TOF) (110.07 h-1) and lower activation energy (38.79 kJ mol-1) in oxidative desulfurization (ODS) with good recyclability. HO˙ radical was found to be the active species involved in ODS as confirmed by the EPR and scavenger experiments. Additionally, the fabricated catalyst can be conveniently separated and recycled within an externally applied magnetic field.