Two dimensional Rh/Fe3O4/g-C3N4-N enabled hydrazine mediated catalytic transfer hydrogenation of nitroaromatics: A predictable catalyst model with adjoining Rh

An interfacial synergism effect of Pd-g-C3N4 in Pd/g-C3N4 for highly active and selective hydrogenation of 4-nitrophenol

Herein, we report that Pd nanoparticles (NPs) anchored on graphitic nitride carbon (Pd/g-C3N4) catalysts with various Pd contents (1.55 wt%, 0.14 wt%, 0.04 wt%) are successfully prepared via a simple NaBH4 reduction method, exhibiting excellent catalytic activity and selectivity toward 4-aminophenol (4-AP) in 4-nitrophenol (4-NP) selective hydrogenation. 4-NP is completely converted to 4-AP (yield ∼ 100%) under quite moderate reaction conditions (40 °C, 2.0 MPa H2 and 5 min) over the 1.55 wt% Pd/g-C3N4 catalyst, with a high reaction rate r = 134.4 mol4-NP molPd-1 min-1. The excellent catalytic performance can be attributed to the following reasons: (1) a higher ratio of Pd(0)/Pdn+ provides much more exposed active sites for the potential adsorption and activation of the reactants, which is beneficial for increasing the reaction rate and catalytic activity; (2) Pd NPs are highly dispersed on g-C3N4 due to the strong interaction of Pd-N or Pd-C; (3) the interfacial synergism effect between Pd NPs and g-C3N4 enables the effective adsorption and activation of H2 (4-NP) at Pd (g-C3N4), promoting the catalytic hydrogenation of 4-NP and improving their catalytic properties. In addition, this catalyst has superior reusability.

Magnetically Reusable Fe3O4@NC@Pt Catalyst for Selective Reduction of Nitroarenes

A novel reusable Fe3O4@NC@Pt heterogeneous catalyst was synthesized by immobilizing platinum on nitrogen-doped carbon magnetic nanostructures. It was characterized by infrared analysis (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). The catalytic efficiency of Fe3O4@NC@Pt was investigated by reduction of nitro aromatic compounds. The catalyst showed good catalytic activity, wide range of substrates, and good chemical selectivity, especially for the substrates of compounds containing halide and carbonyl groups. The magnetically catalyst can readily be reused up to ten cycles without loss of catalytic activity. Moreover, the key pharmaceutical intermediate Lorlatini can be facilely achieved through this strategy.

Microstructural changes caused by Ba and Pr doping in nanosized Bi2Ce2O7 leading to interesting optical, magnetic, and catalytic properties

The microstructural changes arising out of the inclusion of electropositive Ba²⁺ and praseodymium capable of showing variable valences in Bi₂Ce₂O₇ have been correlated with the optical, magnetic, and catalytic properties.

Ultra-small FeS2 nanoparticles for highly efficient chemoselective transfer hydrogenation of nitroarenes

Ultra-small FeS2 nanoparticles are shown to give superior catalytic performance in hydrogen transfer reactions for the synthesis of substituted anilines.

Covalent organic frameworks bearing pillar[6]arene-reduced Au nanoparticles for the catalytic reduction of nitroaromatics

While tremendous advancements in 2D materials anchoring Au nanoparticles have been made, it is an urgent challenge to explore a green and facile approach for obtaining small-size Au nanoparticles. The rise of 2D covalent organic framework (COF) presents more-promising candidates for constructing excellent sites for loading metal nanoparticles. In this study, a novel 2D heterogeneous hybrid nanomaterial (P6-Au-COF) based on COF and pillar[6]arene (P6) reduced Au nanoparticles (P6-Au) is prepared by a simple and green procedure. The Au nanoparticles with an average small diameter of 2-3 nm are homogeneously dispersed on the surface of the COF. The P6-Au-COF hybrid material shows highly catalytic performance for the reduction of nitrophenol isomers when compared with commercial Pd/C catalyst and other reported materials. The P6-Au-COF hybrid material exhibits durable recyclablility and stability during the catalytic reaction. Considering the outstanding merits of the heterogeneous 2D catalyst of P6-Au-COF as well as the simple and green preparation, this research might not only present enormous opportunities for stabilized, high-performance and sustainable catalysts, but be applied in other frontier study of sustainable functionalized nanocomposites and advanced materials.

Hierarchical porous carbon material restricted Au catalyst for highly catalytic reduction of nitroaromatics

In this study, four kinds of porous carbon materials were used as supports to anchor gold nanoparticles (AuNPs) for catalytic reduction of nitroaromatics and 4-nitrophenol (4-NP) was employed as a model material. Results identified that carbon black (CB) restricted-Au catalyst (Au/CB) provided large specific surface area, small AuNPs size, and low cost, which showed highly catalytic activity for 4-NP reduction. Besides, with the increase of Au loadings, the catalytic activity of Au/CB was enhanced and the 1.2 wt% of Au loading exhibited the best catalytic activity with the high rate of 0.8302 min^-1 and the turnover frequency of 492.50 h^-1. Universality and real water application demonstrated that the as-prepared Au/CB catalyst was promising candidate for other phenols and azo dyes reduction and had great potential for practical application. Furthermore, after ten cycles, Au/CB still retained satisfying stability and activity. These results suggested that the larger specific surface area and smaller particle size attributing to the porosity of CB were conducive to improving the catalytic activity of Au catalysts. This design shows high potential of hierarchical porous carbon materials for highly catalytic reaction in many fields, especially the water purification.

Magnetically Hollow Pt Nanocages with Ultrathin Walls as a Highly Integrated Nanoreactor for Catalytic Transfer Hydrogenation Reaction

Fabricating efficient and stable nanocatalysts for chemoselective hydrogenation of nitroaromatics is highly desirable because the amines hold tremendous promise for the synthesis of nitrogen containing chemicals. Here, a highly reactive and stable porous carbon nitride encapsulated magnetically hollow platinum nanocage is developed with subnanometer thick walls (Fe3O4@snPt@PCN) for this transformation. This well-controlled nanoreactor is prepared via the following procedures: the preparation of core template, the deposition of platinum nanocage with subnanometer thick walls, oxidative etching, and calcination. This highly integrated catalyst demonstrates excellent performance for the catalytic transfer hydrogenation of various nitroaromatics and the reaction can reach >99% conversion and >99% selectivity. With the ultrathin wall structure, the atom utilization of platinum atoms is highly efficient. The X-ray photoelectron spectroscopy results indicate that partial electrons transfer from the iron oxides to Pt nanowalls, and this increases the electron density of snPt nanoparticles, thus promoting the catalytic activity for the transfer hydrogenation of nitroaromatics. For the reduction of 4-nitrophenol, the reaction rate constant K app is 0.23 min-1 and the turnover frequency (TOF) is up to 3062 h-1. Additional reaction results illustrate that this magnetic nanoreactor can be reused more than eight times and it is a promising catalytic nanoplatform in heterogeneous catalysis.

Catalytic applications of β-cyclodextrin/palladium nanoparticle thin film obtained from oil/water interface in the reduction of toxic nitrophenol compounds and the degradation of azo dyes

A supramolecular catalyst of Pd/β-cyclodextrin thin film is synthesized via a facile and one-pot procedure at an oil–water interface and applied for the reduction of toxic nitrophenol compounds and the degradation of harmful azo dyes.