Selective reduction of ketone/aldehydes to alcohols is of great importance in green chemistry and chemical engineering. Highly efficient catalysts are still demanded to work under mild conditions, especially at room temperature. Here we present a synergistic function of singleatom palladium (Pd 1 ) and nanoparticles (Pd NPs ) on TiO 2 for highly efficient ketone/aldehydes hydrogenation to alcohols at room temperature. Compared to simple but inferior Pd 1 /TiO 2 and Pd NPs /TiO 2 catalysts, more than twice activity enhancement is achieved with the Pd 1+NPs /TiO 2 catalyst that integrates both Pd 1 and Pd NPs on mesoporous TiO 2 supports, obtained by a simple but large-scaled spray pyrolysis route. The synergistic function of Pd 1 and Pd NPs is assigned so that the partial Pd 1 dispersion contributes enough sites for the activation of C=O group while Pd NPs site boosts the dissociation of H 2 molecules to H atoms. This work not only contributes a superior catalyst for ketone/aldehydes hydrogenation, but also deepens the knowledge on their hydrogenation mechanism and guides people to engineer the catalytic behaviors as needed.

Hollow nanomaterials have attracted a broad interest in multidisciplinary research due to their unique structure and preeminent properties. Owing to the high specific surface area, well-defined active site, delimited void space, and tunable mass transfer rate, hollow nanostructures can serve as excellent catalysts, supports, and reactors for a variety of catalytic applications, including photocatalysis, electrocatalysis, heterogeneous catalysis, homogeneous catalysis, etc. Based on state-of-the-art synthetic methods and characterization techniques, researchers focus on the purposeful functionalization of hollow nanomaterials for catalytic mechanism studies and intricate catalytic reactions. Herein, an overview of current reports with respect to the catalysis of functionalized hollow nanomaterials is given, and they are classified into five types of versatile strategies with a top-down perspective, including textual and composition modification, encapsulation, multishelled construction, anchored single atomic site, and surface molecular engineering. In the detailed case studies, the design and construction of hierarchical hollow catalysts are discussed. Moreover, since hollow structure offers more than two types of spatial-delimited sites, complicated catalytic reactions are elaborated. In summary, functionalized hollow nanomaterials provide an ideal model for the rational design and development of efficient catalysts.

We prepared single Ni atoms embedded in an N-doped carbon catalyst with the assistance of metal organic frameworks. The dispersion of Ni atoms was verified by taking X-ray absorption fine structure measurements. Under the typical conditions for hydrogenation of acetylene, this single-site heterogeneous catalyst showed great potential as an alternative to Pd-based materials.

Abstract

Epoxidation is an efficient chemical process for manufacturing styrene oxide; however, it remains a huge challenge to develop cost-effective and environment-friendly catalysts for facilitating this process. Herein, we reported a single-atomic-site Ag catalyst supported by mesoporous graphitic carbon nitride (Ag1/mpg-C3N4) with an Ag loading of up to 10.21 wt %, which is the highest loading among single-atomic-site Ag catalysts. The single-atomic-site Ag replaced the nitrogen of mpg-C3N4, possessing the Ag1–C2N1 structure. The Ag1/mpg-C3N4 catalyst with the Ag1–C2N1 structure exhibited outstanding catalytic performance for styrene epoxidation with excellent conversion (96%) and high selectivity (81%). This performance was superior to that of the analogous Ag nanoparticle/mpg-C3N4 catalyst and previously reported catalysts. Density functional theory calculations showed that the absorbed superoxide-like O2 species and the much lower reaction barrier to generating styrene oxide than the other products lead to high activity and selectivity, respectively.