Palladium single-atom catalysts synthesized by a gas-assisted redispersion strategy for efficient benzaldehyde hydrogenation.

A simple and efficient strategy was developed for the synthesis of Pd single-atom catalysts (PdSA/G) by nitric acid vapor-assisted redispersion. The as-prepared PdSA/G displayed robust catalytic performance in the selective hydrogenation reaction of benzaldehyde. This work paves a new way for the design of supported Pd single-atom catalysts.

Fully-Exposed Pd Cluster Catalyst: An Excellent Catalytic Antibacterial Nanomaterial.

Exploring antibacterial nanomaterials with excellent catalytic antibacterial properties has always been a hot research topic. However, the construction of nanomaterials with robust antibacterial activity at the atomic level remains a great challenge. Here a fully-exposed Pd cluster atomically-dispersed on nanodiamond-graphene (Pdn /ND@G) with excellent catalytic antibacterial properties is reported. The fully-exposed Pd cluster nanozyme provides atomically-dispersed Pd cluster sites that facilitate the activation of oxygen. Notably, the oxidase-like catalytic performance of the fully-exposed Pd cluster nanozyme is much higher than that of Pd single-atom oxidase mimic, Pd nanoparticles oxidase mimic and even the previously reported palladium-based oxidase mimics. Under the density functional theory (DFT) calculations, the Pd cluster sites can efficiently catalyze the decomposition of oxygen to generate reactive oxygen species, resulting in strong antibacterial properties. This research provides a valuable insight to the design of novel oxidase mimic and antibacterial nanomaterial.

PdZn alloy nanoparticles encapsulated within a few layers of graphene for efficient semi-hydrogenation of acetylene.

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.

Steam treatment: a facile and effective process for the removal of PVP from shape-controlled palladium nanoparticles.

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.

Crystalline (Ni1-xCox)5TiO7 nanostructures grown in situ on a flexible metal substrate used towards efficient CO oxidation.

Severe environmental contamination and the urgent demand for a clean atmosphere require an efficient and low-cost solution to address problems such as CO emission. In this study, we report the in situ integration of non-noble (Ni1-xCox)5TiO7 nanostructures with different Co concentrations and tunable size on a flexible metal network support using a conventional PEO method; we further report their utilization for efficient CO oxidation. It was found that the Co/Ni ratios in the original electrolyte precursors directly result in the different size and morphology evolution. The (Ni1-xCox)5TiO7 nanowire arrays with x = 0.16 exhibit the best performance towards CO catalytic oxidation along with a good catalytic stability. Further analysis using XPS indicates that the CO catalytic oxidation was mainly determined by the amount of defective oxygen, lattice oxygen and surface area. The single crystal nature, large surface area, excellent CO catalytic capability and strong substrate adhesion of the (Ni1-xCox)5TiO7 nanostructures on a flexible metal substrate will open up more applications in CO oxidation ranging from processing autovehicle exhaust to chemical gas emissions in the industry.

NiCo nanoalloy encapsulated in graphene layers for improving hydrogen storage properties of LiAlH4.

NiCo nanoalloy (4-6 nm) encapsulated in grapheme layers (NiCo@G) has been prepared by thermolysis of a 3D bimetallic complex CoCo[Ni(EDTA)]2·4H2O and successfully employed as a catalyst to improve the dehydrogenation performances of LiAlH4 by solid ball-milling. NiCo@G presents a superior catalytic effect on the dehydrogenation of LiAlH4. For LiAlH4 doped with 1 wt% NiCo@G (LiAlH4-1 wt% NiCo@G), the onset dehydrogenation temperature of LiAlH4 is as low as 43 °C, which is 109 °C lower than that of pristine LiAlH4. 7.3 wt% of hydrogen can be released from LiAlH4-1 wt% NiCo@G at 150 °C within 60 min. The activation energies of LiAlH4 dehydrogenation are extremely reduced by 1 wt% NiCo@G doping.

Ionic liquid based polymeric liposomes: A stable and biocompatible soft platform for bioelectrochemistry.

Polymeric liposomes (denoted as ILs-polysomes) are a biocompatible and conductive nanomaterial, which was first utilised as the electrode material for immobilising and biosensing redox enzyme horseradish peroxide (HRP). The morphology and surface property of IL-polysomes was characterised and systematically compared with unpolymerised ionic liquid based liposomes (denoted as ILs-liposomes). Differing from IL-liposomes, IL-polysomes preserves their original morphology and bilayer membrane structure on glassy carbon (GC) electrodes due to the cross-linking of polymerised lipids, thus exhibiting excellent stability and specific biocompability. Because of the existence of imidazolium ionic liquid moieties on the outer surface, IL-polysomes displays a positive charge in aqueous solution, leading to oppositely charged HRP self-assembling onto the vesicles to form HRP/IL-polysomes/PVA/GC electrodes. Owing to the combined merits of ILs and liposomes, electron transfer between HRP-Fe(III)/Fe(II) redox couples of immobilised enzymes and GC electrodes can be achieved. Therefore, HRP/IL-polysomes/PVA/GC electrodes exhibited good electrocatalytic performance toward the electrocatalysis of H2O2. Accordingly, IL-polysomes could act as an efficient charged platform for the self-assembled redox enzymes to realise direct electrochemistry. IL-polysomes have a promising application in the fabrication of third-generation electrochemical biosensors.

Size-controllable Ni5TiO7 nanowires as promising catalysts for CO oxidation.

Ni5TiO7 nanowires with controllable sizes are synthesized using PEO method combined with impregnation and annealing at 1050(o)C in air, with adjustment of different concentrations of impregnating solution to control the dimension of nanowires. The resulting nanowires are characterized in details using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray analysis. In addition, the CO catalytic oxidation performance of the Ni5TiO7 nanowires is investigated using a fixed-bed quartz tubular reactor and an on-line gas chromatography system, indicating that the activity of this catalytic system for CO oxidation is a strong dependency upon the nanocrystal size.When the size of the Ni5TiO7 nanowires is induced from 4 µm to 50 nm, the corresponding maximum conversion temperature is lowered by ~100 (o)C.

Rapid degradation of phenanthrene by using Sphingomonas sp. GY2B immobilized in calcium alginate gel beads.

The strain Sphingomonas sp. GY2B is a high efficient phenanthrene-degrading strain isolated from crude oil contaminated soils that displays a broad-spectrum degradation ability towards PAHs and related aromatic compounds. This paper reports embedding immobilization of strain GY2B in calcium alginate gel beads and the rapid degradation of phenanthrene by the embedded strains. Results showed that embedded immobilized strains had high degradation percentages both in mineral salts medium (MSM) and 80% artificial seawater (AS) media, and had higher phenanthrene degradation efficiency than the free strains. More than 90% phenanthrene (100 mg x L(-1)) was degraded within 36 h, and the phenanthrene degradation percentages were >99.8% after 72 h for immobilized strains. 80% AS had significant negative effect on the phenanthrene degradation rate (PDR) of strain GY2B during the linear-decreasing stage of incubation and preadsorption of cells onto rice straw could improve the PDR of embedded strain GY2B. The immobilization of strain GY2B possesses a good potential for application in the treatment of industrial wastewater containing phenanthrene and other related aromatic compounds.

[Microcalorimetric investigation of two cephalosporins on colon bacteria activity].

The effects of cephradinum and ceftazidime on the metabolism of Escherichia coli (E. coli) DH5alpha was determined by microcalorimetry. The microbial activity was recorded as power-time curves through an ampoule method with a TAM Air Isothermal Microcalorimeter at 37 degrees C. The parameters such as the growth rate constant (k), inhibitory ratio (I), the maximum power output (Pm) and the time (tm) corresponding to the maximum power output were calculated. The results show that the ceftazidime has a better inhibitory effect on E. coli DH5alpha than cephradinum.