Disulfide is an important organic reagent and synthetic intermediate that is widely used in organic synthesis, polymers, and other fields, but its synthesis still suffers from many environmental pollution and economic problems. Here, we present an environmentally friendly and efficient base-free aerobic oxidative thiol coupling catalyzed by heterogeneous CoOx nanoclusters entrapped in hierarchical silicalite-1 zeolite, synthesized by combining silane pore expansion and metal coordination methods under hydrothermal conditions. It is confirmed that open hierarchical channels favor mass diffusion, and the chemical valence of Co species in CoOx/h-S-1-H is +2, which is different from that of Co3O4 particles in CoOx/h-S-1-I. CoOx nanoclusters, are strongly fixed in the channels of silicalite-1 zeolite via Co−O−Si bonds, which is of great importance for the high catalytic activity in both symmetrical and unsymmetrical oxidative thiol coupling reactions. After recycling experiments four times, the CoOx/h-S-1-H used has almost the same chemical state and the same distribution of Co(II) species as the fresh catalysts. Based on DFT calculations and inhibition experiments, the oxidative coupling of thiols undergoes a free radical mechanism in which Co(III) causes RS−H cleavage into RS· and H· species. Subsequently, two RS· radicals are coupled to disulfides, while H· radicals react with the O species to form H2O molecules. This work not only provides guidance on catalyst design and parameter optimization for oxidative thiol coupling but also advances the understanding of the aerobic oxidation mechanism.
Non-precious metal electrocatalysts (such as Fe–N–C materials) for the oxygen (O 2 ) reduction reaction demand a high catalyst loading in fuel cell devices to achieve workable performance. However, the extremely low solubility of O 2 in water creates severe mass transport resistance in the thick catalyst layer of Fe–N–C catalysts. Here, we introduce silicalite-1 nanocrystals with hydrophobic cavities as sustainable O 2 reservoirs to overcome the mass transport issue of Fe–N–C catalysts. The extra O 2 supply to the adjacent catalysts significantly alleviated the negative effects of the severe mass transport resistance. The hybrid catalyst (Fe–N–C@silicalite-1) achieved a higher limiting current density than Fe–N–C in the half-cell test. In the H 2 –O 2 and H 2 –air proton exchange membrane fuel cells, Fe–N–C@silicalite-1 exhibited a 16.3% and 20.2% increase in peak power density compared with Fe–N–C, respectively. The O 2 -concentrating additive provides an effective approach for improving the mass transport imposed by the low solubility of O 2 in water.
All-inorganic CsPbBr3 perovskite quantum dots (PQDs) show superior photophysical properties and great potential in various optoelectronic devices, but their low lattice formation energy and high delocalization of surface ions make them susceptible to ambient conditions. In this work, the hierarchical silicalite-1 zeolite co-templated by carbon nanotubes (CNTs) and tetrapropylammonium hydroxide (TPAOH) was applied to encapsulate CsPbBr3 PQDs. Particularly, distinct nanosized CNTs, mass ratios of zeolite to CsPbBr3, and thermal diffusion temperature were systematically studied to optimize the loading capacity and luminescence efficiency of CsPbBr3 PQDs. Consequently, the micro-/mesoporous silicalite-1 confined CsPbBr3 PQD nanocomposite obtained at 700 °C exhibited the best luminescence performance with a full-width at half-maximum (FWHM) of 25 nm, a high PLQY of ∼61.9% and an ultrahigh stability of >100 days in H2O. The CsPbBr3/silicalite-1 nanocomposite shows dual-mode temperature monitoring performance in terms of fluorescence emission intensity and spectral shift, rendering it a promising candidate for credible optical thermometry. Latent fingerprint identification and selective Fe3+ fluorescence sensing applicability of the CsPbBr3/silicalite-1 nanocomposite were then developed. Also, a reversible off/on switching of the green fingerprint image under UV-light irradiation can be easily modulated by spraying Fe3+ aqueous solution and pure H2O, respectively, achieving an effective anti-counterfeiting application.
危险品化学品经营许可证（带存储）