PdZn alloy nanoparticles encapsulated within a few layers of graphene supported on ZnO nanowires (PdZn@C/ZnO) exhibit enhanced catalytic performance and robust long-term stability in semi-hydrogenation of acetylene to ethylene. The enhanced ethylene selectivity of PdZn@C/ZnO originates from the confining environment of the graphene cover, which can promote desorption of ethylene from the PdZn surface, avoiding the over-hydrogenation of ethylene to ethane.

N-doped graphene (N-graphene) confined Pt nanoparticles (NPs) with core-shell structure supported on carbon nanotubes (CN@Pt/CNTs) are prepared by a facile two-step process. The obtained N-graphene nanoshell ranging from 2 to 4 graphene layers and the Pt NPs covered within N-graphene are uniformly dispersed on the CNTs. The as-prepared CN@Pt/CNTs exhibits much higher styrene selectivity and robust recycle ability in selective hydrogenation of phenylacetylene, compared with that of traditional CNTs supported Pt NPs (Pt/CNTs). DFT calculation reveals that the high styrene selectivity is derived from the confinement effect of N-graphene, which facilitates desorption of styrene from Pt NPs surface, avoiding the over hydrogenation of styrene to benzylethane. The present method paves a new way to design high selective Pt based hydrogenation catalyst. (c) 2019 Elsevier Ltd. All rights reserved.

A facile glucose assisted one-step method for preparing highly dispersed Ag nanoparticles (Ag-NPs) encapsulated into carbon nanotubes (CNTs) was developed. The CNTs with open tips are employed as the nano-reactor and support, silver nitrite (AgNO3) is used as the precursor and glucose is employed both as the reducing and protecting agent in the whole preparation process. The Ag-NPs with diameters of 6-10 nm are uniformly assembled into the channel of CNTs. The detailed structure and morphology of Ag-NPs encapsulated into CNTs (Ag-NPs@CNTs) were systematically characterized. The obtained Ag-NPs@CNTs exhibits an enhanced antibacterial activity against Escherichia coli, comparing with those of Ag-NPs supported on activate carbon (Ag-NPs/AC) and on CNTs (Ag-NPs/CNTs) prepared by the traditional wetness impregnation method. (c) 2018 Elsevier Ltd. All rights reserved.

In general, a colloidal method employing polyvinylpyrrolidone (PVP) as the stabilizer has been proven particularly suitable for preparing Pd nanoparticles (Pd-NPs) with controlled morphology and size. However, this surfactant will seriously cover the Pd-NP surface, which is detrimental for catalytic activity. In this paper, we reported a method to remove PVP from the carbon nanotube (CNT) supported Pd nanocubes (Pd-NCs) and Pd nanooctahedra (Pd-NOs) by steam treatment in a lab-made reactor. We found that this method can not only efficiently remove PVP from the Pd-NP surface, but also can well maintain the original structure of Pd-NCs and Pd-NOs, dramatically enhancing the catalytic performance. The present approach may promote potential applications of Pd-NPs prepared by colloidal methods in catalytic fields.