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A Cu-based bimetallic hollow structure can be effectively used to enhance the selective oxidation and electrocatalytic activity of a catalyst and to reduce its cost. In this paper, we developed a facile and scalable method for the construction of CuAu bimetallic hollow particles from Cu2O nanoparticle aggregates (NPAs). The synthetic process includes Au growth on the Cu2O NPA surface and silica encapsulation, which is followed by polyol reduction of Cu2O, calcination in air and etching of the SiO2 layer. The obtained hollow CuAu NPs (average diameter of 540 nm and wall thickness of 60 nm) outperform hollow Cu NPs in terms of catalytic activity in the reduction of 4-nitrophenol by NaBH4 in aqueous solution. The activity factors (K = 354 and 255 s−1 g−1) are 2.4 and 1.7 times larger than that of the hollow Cu catalyst, depending on the Au content in the CuAu particles. In addition, the prepared catalyst was stable in the reaction system and can be recycled via centrifugation without a significant loss of catalytic activity. [ABSTRACT FROM AUTHOR]

An effective and safe route is proposed to prepare supported Mo2C-based catalysts from organic–inorganic hybrids, which exhibit high activity and stability for producing H2from methanol catalytic decomposition. [ABSTRACT FROM AUTHOR]

Development of magnetic nanoparticles (MNPs) for use as supports and exploration of their applications in aqueous catalysis represent an important branch of green chemistry as they enable environmentally friendly and sustainable catalytic processes. Besides the significant merit of easily recovering magnetic nanoparticles from reaction systems, various strategies through surface modification, grafting and selfassembly offer a broad range of approaches for constructing magnetically recoverable heterogeneous catalysts. In this review, we focus on the green catalytic processes and summarize recent advances in organic transformations catalyzed by magnetically recoverable catalysts (MRCs). This paper is divided into two main parts: the first part provides background information on the general preparation, modifications, and characterization, where the modifications of various magnetic nanoparticles through coating with silica, carbon, metal, or polymer are also presented. The second part provides a basic outline of aqueous catalysis based on water-only or water-and-organic solvent cosolvent systems, in which numerous types of organic transformations are catalyzed by magnetically recoverable catalysts. Lastly, perspectives for further development of magnetically recoverable heterogeneous catalysts in aqueous catalysis are addressed. [ABSTRACT FROM AUTHOR]

An efficient method for dispersing active metal colloidal nanoparticles onto supports uniformly is revealed in this paper. The critical feature of this method is to separate the stabilizer simply with the phase-switch function of scCO2; with it the highly dispersed Pd colloidal catalysts were prepared, and the forming procedure is analyzed and discussed in detail. The present work not only overcame the common difficulties of removing the stabilizers in the preparation of supported colloidal particles, but also provided a facile and green process for preparing supported metal colloidal nanoparticles with using the environmentally benign solvent of scCO2. [ABSTRACT FROM AUTHOR]

In this paper, polymer nanocapsules embedded with noble metal nanoparticles and showing a good catalytic activity were prepared by a novel and convenient method. [ABSTRACT FROM AUTHOR]

Lignin nanosizing has received much interest as it offers new potential for value-added applications of the currently under-utilized lignin biopolymers. However, conventional lignin nanosizing technologies often rely on the use of large amounts of toxic organic solvents, and a time-consuming dialysis process that is required to remove the solvents. Herein, we present a novel and effective approach using a binary system consisting of green γ-valerolactone (GVL) and glycerol solvents to prepare lignin nanospheres (LNS) without lignin modification and additional dialysis processes. The rationale of LNS formation lies in the emulsification of uniform lignin-containing GVL droplets in glycerol by a process consisting of (1) heating to 80 °C, and (2) cooling to room temperature. Through this simple process, we obtained very high LNS yield (over 90%), with narrow size distribution (about 275 nm) by using maple kraft lignin as the raw material. This lignin nanosizing approach is universal when applied to different sources/types of lignins. The as-prepared LNS were further applied as a green reducing agent and carrier for the synthesis of Pd nanoparticles (NPs) in a facile in situ reduction process. Pd@LNS exhibited significantly enhanced catalytic capacity in the hydrogen evolution from formic acid and in the reduction of Cr(VI) to Cr(III) compared with bare Pd NPs. The Pd@LNS catalyst demonstrated high recyclability owing to the good chemical stability of LNS and robust loading of Pd NPs on LNS. Consequently, this work offers a green, universal and effective approach for LNS fabrication and presents a promising application of LNS as metal NP carriers for catalysis purposes. [ABSTRACT FROM AUTHOR]

A simple and highly efficient nanostructured catalyst system comprising magnetic Co nanoparticles stabilized by N-doped carbon composite (Co/C–N) was synthesized by one-pot thermal decomposition of a Co-containing MOF. The catalysts were characterized by temperature programmed desorption (TPD), N2 physical adsorption, powder X-ray diffraction (PXRD), Raman spectroscopy, transmission electron microscopy (TEM), scanning electronic microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The catalytic activity of Co/C–N materials was investigated in the selective aerobic oxidation of alcohols in neat water under an atmospheric pressure of air and base-free conditions. As compared to those prepared by traditional impregnation methods, Co/C–N exhibited an efficient performance with significantly improved catalytic activities. Besides conferring high activity and selectivity to the target products, the proposed catalytic system featured a broad substrate scope for both aryl and alkyl alcohols. Furthermore, the magnetically recoverable Co/C–N catalyst could be easily separated from the reaction system by using an external magnetic field and reused at least five times without any significant loss in catalytic efficiency under the investigated conditions. [ABSTRACT FROM AUTHOR]