4 research outputs found

    Shape-Control of Pt–Ru Nanocrystals: Tuning Surface Structure for Enhanced Electrocatalytic Methanol Oxidation

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    Despite the fact that both electrochemical experiments and density functional theory calculations have testified to the superior electrocatalytic activity and CO-poisoning tolerance of platinum–ruthenium (PtRu) alloy nanoparticles toward the methanol oxidation reaction (MOR), the facet-dependent electrocatalytic properties of PtRu nanoparticles are scarcely revealed because it is extremely difficult to synthesize well-defined facets-enclosed PtRu nanocrystals. Herein, we for the first time report a general synthesis of ultrathin PtRu nanocrystals with tunable morphologies (nanowires, nanorods, and nanocubes) through a one-step solvothermal approach and a systematic investigation of the structure-directing effects of different surfactants and the formation mechanism by control experiments and time-dependent studies. In addition, we utilize these {100} and {111} facets-enclosed PtRu nanocrystals as model catalysts to evaluate the electrocatalytic characteristics of the MOR on different facets. Remarkably, {111}-terminated PtRu nanowires exhibit much higher stability and electrocatalytic mass activity toward MOR, which are 2.28 and 4.32 times higher than those of {100}-terminated PtRu nanocubes and commercial Pt/C, respectively, indicating that PtRu {111} facets possess superior methanol oxidation activity and CO-poisoning resistance relative to {100} facets. Our present work provides a series of well-defined PtRu nanocrystals with tunable facets which would be ideal model electrocatalysts for fundamental research in fuel cell electrocatalysis

    High-Index Facets Bounded Platinum–Lead Concave Nanocubes with Enhanced Electrocatalytic Properties

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    High-index facets bounded platinum-based alloy nanocrystals usually exhibit enhanced electrocatalytic activity. However, the high surface energy, thermodynamic instability, and lattice mismatch make it a significant challenge to synthesize well-defined bimetallic nanocrystals with high-index facets. Here we developed a one-step wet-chemical synthesis of uniform PtPb concave nanocubes (CNCs) enclosed by {520} high-index facets. The as-prepared PtPb CNCs exhibited high synthetic yield and highly concave structure with an average size of 14 nm. Moreover, the synergistic effects and exposed {520} facets endowed the PtPb CNCs with excellent stability and electrocatalytic mass activity toward the methanol oxidation reaction (MOR), which was 2.16- and 4.62-times higher than PtPb nanocubes (NCs) and commercial Pt/C catalysts, respectively. This work provides a new way for rational design and practical application of efficient catalysts

    Easy Synthesis and Imaging Applications of Cross-Linked Green Fluorescent Hollow Carbon Nanoparticles

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    We propose an ingenious method for synthesizing cross-linked hollow fluorescent carbon nanoparticles (HFCNs) with green emission by simply mixing acetic acid, water, and diphosphorus pentoxide. This is an automatic method without external heat treatment to rapidly produce large quantities of HFCNs, in contrast to other syntheses of fluorescent carbon nanoparticles that required high temperature, complicated operations, or long reaction times. Characterizations of HFCNs through high-resolution transmission electron microscopy, infrared/Raman spectroscopy, and X-ray diffraction indicate that abundant small oxygenous graphite domains existed and endowed the HFCNs with fluorescent properties. After simple post-treatments, the cross-linked HFCNs can be used for cell-imaging applications. Compared with traditional dyes and CdTe quantum dots, HFCNs are the superior fluorescent bioimaging agent according to their low toxicity, stability, and resistance to photobleaching. The HFCNs were also applied to watermark ink and fluorescent powder, showing their promising potentials for further wide usage

    A Flexible Metal–Organic Framework: Guest Molecules Controlled Dynamic Gas Adsorption

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    A flexible metal–organic framework (MOF) of [Zn<sub>3</sub>(btca)<sub>2</sub>(OH)<sub>2</sub>]·(guest)<sub><i>n</i></sub> (H<sub>2</sub>btca = 1,2,3-benzotriazole-5-carboxylic acid) that exhibits guest molecule-controlled dynamic gas adsorption is reported in which carbon dioxide molecules rather than N<sub>2</sub>, He, and Ar induce a structural transition with a corresponding appearance of additional steps in the isotherms. Physical insights into the dynamic adsorption behaviors of flexible compound <b>1</b> were detected by gas adsorption at different temperatures and different pressures and confirmed by Fourier transform infrared spectroscopy and molecular simulations. Interestingly, by taking advantage of the flexible nature inherent to the framework, this MOF material enables highly selective adsorption of CO<sub>2</sub>/N<sub>2</sub>, CO<sub>2</sub>/Ar, and CO<sub>2</sub>/He of 36.3, 32.6, and 35.9, respectively, at 298 K. This class of flexible MOFs has potential applications for controlled release, molecular sensing, noble gas separation, smart membranes, and nanotechnological devices
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