Zongyuan Wang

Three-dimensional Printed Acrylonitrile Butadiene Styrene Framework Coated with Cu-BTC Metal-organic Frameworks for the Removal of Methylene Blue

Three-dimensional (3D) printing was applied for the fabrication of acrylonitrile butadiene styrene (ABS) framework. Functionalization of the ABS framework was then performed by coating of porous Cu-BTC (BTC = benzene tricarboxylic acid) metal-organic frameworks on it using a step-by-step in-situ growth. The size of the Cu-BTC particles on ABS was ranged from 200 nm to 900 nm. The Cu-BTC/ABS framework can take up most of the space of the tubular reactor that makes the adsorption effective with no need of stirring. Methylene blue (MB) can be readily removed from aqueous solution by this Cu-BTC/ABS framework. The MB removal efficiency for solutions with concentrations of 10 and 5 mg/L was 93.3% and 98.3%, respectively, within 10 min. After MB adsorption, the Cu-BTC/ABS composite can easily be recovered without the need for centrifugation or filtration and the composite is reusable. In addition the ABS framework can be recovered for subsequent reuse. A significant advantage of 3D-printed frameworks is that different frameworks can be easily fabricated to meet the needs of different applications. This is a promising strategy to synthesize new frameworks using MOFs and polymers to develop materials for applications beyond adsorption.

Perspective on CO oxidation over Pd-based catalysts

CO oxidation is one of the most extensively investigated reactions in the field of heterogeneous catalysis because of its importance in both environmental protection and fundamental studies. CO oxidation over Pd catalysts has attracted significant attention not only because of its high activity. It is an excellent model reaction for the study of the structure, metal–support interaction and other issues of various Pd-based catalysts with many important applications beyond CO oxidation. It is simple and can be easily operated with low cost. Density functional theoretical studies can be directly and easily combined with experimental investigations. Carbon monoxide itself is an excellent probe molecule for catalyst characterization. In this perspective, we summarize the progress in the study of CO oxidation over Pd-based catalysts. Various influencing factors will be discussed. Future challenges and opportunities will be addressed.

Enhanced activity for CO oxidation over WO3 nanolamella supported Pt catalyst.

WO3 nanolamella supported Pt catalyst has been prepared and applied for CO oxidation in this work. A significantly enhanced activity has been achieved, compared to that of the Pt catalyst supported by the WO3 nanoparticle. The catalyst characterization using X-ray diffraction (XRD), scanning electronic microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and N2 adsorption-desorption confirms that the WO3 nanolamella supported Pt catalyst possesses higher Pt dispersion, improved metal-support interaction with a higher electron density of Pt, and a weak adsorption of CO, leading to the significantly enhanced activity for CO oxidation.

Floating silver film: A flexible surface-enhanced Raman spectroscopy substrate for direct liquid phase detection at gas–liquid interfaces

In recent years, surface-enhanced Raman spectroscopy (SERS) has developed rapidly and is used for the detection of molecules and biomolecules in liquids. However, few studies have focused on SERS using a water surface as the substrate. A floating metal film on water is desirable for an enhanced SERS performance. In this work, silver nanoparticles (Ag NPs) encased in poly(vinylpyrrolidone) films (Ag-PVP films) were synthesized on the surface of an aqueous solution by room temperature electron reduction. A floating silver film on a water surface was thereby achieved and is reported for the first time. The synthesized Ag-PVP film is an excellent flexible substrate for SERS and has other potential applications. Using the floating silver film as a flexible SERS substrate, 10–11 M of 4-aminothiophenol, 10–6 M of riboflavin, 10–9 M of 4-mercaptobenzoic acid, 10–7 M of 4-mercaptophenol, and 10–7 M of 4-aminobenzoic acid are identified, demonstrating potential use for the floating substrate in the liquid-phase detection of molecules.

The room temperature electron reduction for the preparation of silver nanoparticles on cotton with high antimicrobial activity

Functionalization of cotton by fabricating Ag nanoparticles (NPs) on cotton surface has aroused great interest for its promising applications for chemical, electronic, photonic and many other devices. Herein, a simple and rapid room temperature electron reduction, which uses argon glow discharge as the electron source, was employed to fabricate Ag NPs on cotton without using any chemical reducing agent. The color of Ag NP loaded cotton changes from light yellow to black upon the increasing Ag loading amount, while the average size of Ag NPs on the cotton barely changes from 4.4 to 6.3nm. This indicates the color change is due to the size of Ag aggregates rather than the size of single Ag NP, as demonstrated by scanning electron microscope (SEM) and UV-vis absorption analyses. The functionalized fabric exhibits high antimicrobial activity against both Gram-negative bacterium E. coli and Gram-positive bacterium B. subtilis.

Highly Active and Stable Pt–Pd Alloy Catalysts Synthesized by Room-Temperature Electron Reduction for Oxygen Reduction Reaction

Carbon‐supported platinum (Pt) and palladium (Pd) alloy catalyst has become a promising alternative electrocatalyst for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells. In this work, the synthesis of highly active and stable carbon‐supported Pt–Pd alloy catalysts is reported with a room‐temperature electron reduction method. The alloy nanoparticles thus prepared show a particle size around 2.6 nm and a core–shell structure with Pt as the shell. With this structure, the breaking of O–O bands and desorption of OH are both promoted in electrocatalysis of ORR. In comparison with the commercial Pt/C catalyst prepared by conventional method, the mass activity of the Pt–Pd/C catalyst for ORR is shown to increase by a factor of ≈4. After 10 000‐cycle durability test, the Pt–Pd/C catalyst is shown to retain 96.5% of the mass activity, which is much more stable than that of the commercial Pt/C catalyst.

Silver nanoparticle aggregates by room temperature electron reduction: preparation and characterization

A step-by-step room temperature electron reduction has been developed in this work to prepare silver nanoparticle aggregates on anodic aluminium oxide (AAO) substrate. No chemical reducing agent is needed. The aggregates are formed by silver nanoparticles with a particle size of about 3 nm. The colour of the silver nanoparticle aggregates can be adjusted from yellow (with small Ag loading) to dark (with high Ag loading). Especially, the colour of these aggregates depends on the size of the Ag nanoparticle aggregate, rather than on the size of the single Ag nanoparticles. The silver aggregate/AAO composites show an outstanding surface plasmon resonance (SERS) characteristic. The Raman enhancement factor reaches as high as 1.054 × 107. The silver nanoparticle aggregates can be dispersed as Ag nanoparticles within a liquid solution with the removal of the substrate under the assistance of ultrasonic dispersion. The silver nanoparticle aggregates obtained by this step-by-step electron reduction provide a convenient and sustainable means for the storage of metal nanoparticles.

L-Phenylalanine-Templated Platinum Catalyst with Enhanced Performance for Oxygen Reduction Reaction

Pt-based materials are the most efficient catalysts for the oxygen reduction reaction (ORR) in proton-exchange membrane fuel cells. However, fabrication of active and stable Pt catalysts still remains challenging. In this work, Pt-l-phenylalanine (Pt-LPHE) films, with highly dispersed Pt nanoparticles (NPs) featuring predominately (111) facets, have been prepared via a room-temperature electron reduction method. Loading Pt-LPHE onto carbon support produces a novel nanomaterial (Pt-AL/C), resulting in a simultaneous loading of highly dispersed Pt NPs and N doping. Density functional theory calculations demonstrate that the N dopants stabilize the Pt NPs and reduce the *O/*OH binding energies on the Pt NPs. As a result, the Pt-AL/C nanomaterial shows significantly enhanced ORR activity and stability over commercial Pt/C after 10 000 cycle stability tests. This work provides a novel eco-friendly and energy-neutral approach for preparing metal NPs with controllable structures and sizes.