Probing buried carbon nanotubes within polymer-nanotube composite matrices by atomic force microscopy

Multi-walled carbon nanotubes (MW-CNT) inside a polyamide-6 (PA6)-MW-CNT composite were visualized by atomic force microscopy (i) in a field-assisted intermittent contact and (ii) in the tunneling (TUNA) mode. Individual buried MW-CNTs were clearly discerned within the PA6 matrix. An average diameter of 33 ± 5 nm of the MW-CNTs was determined based on field-assisted intermittent contact mode AFM images, which is consistent with the expected size of PA6-coated MW-CNTs. Single well dispersed MW-CNTs that are located in the sub-surface region of the composite were also observed in the TUNA mode. These new AFM approaches circumvent the tedious sample preparation based on ultramicrotoming required for high resolution electron microscopy studies to obtain “in-depth” morphological information and hence are expected to facilitate the analysis of CNT-based and other nanocomposites in the future.     

Substituted metal carbonyls XIII. Fe(CO)4(η-dppf) [where DPPF = (Ph2PC5H4)2Fe]: a convenient building block for heterometallic complexes

The potential of Fe(CO)₄(η¹-dppf) (dppf = 1,1′-bis(diphenylphosphino)ferrocene) as a precursor for heterometallic species is fully expanded in the synthesis of (OC)₄Fe(μ-dppf)Cr(CO)₅, (OC)₄Fe(μ-dppf)W(CO)₅, and (OC)₄Fe(μ-dppf)Mn₂(CO)₉, all of which have been characterized by IR, NMR (¹H and ³¹P) and elemental analyses. The low energy requirement of TMNO (Me₃NO · 2H₂O)decarbonylation allows the formation of monosubstituted Mn₂(CO)₁₀ as the major product. This aspect is further substantiated by the isolation of Mn₄(CO)₁₈(μ-dppf) in which the single bridging of a diphosphine group between two Mn₂(CO)₉ moieties is unprecedented.     

Binder-less and free-standing Co–Fe metal nanoparticles-decorated PVdF-HFP nanofiber membrane as an electrochemical probe for enzyme-less glucose sensors

Co–Fe bimetallic nanoparticles-affixed polyvinylidene fluoride-co-hexafluoropropylene (PVdF-HFP) nanofiber membrane is fabricated using the electrospinning and chemical reduction techniques. The semicrystalline polymeric backbone decorated with the highly crystalline Co–Fe bimetallic nanoparticles enunciates the mechanical integrity, while the incessant and swift electron mobility is articulated with the consistent dissemination of bimetallic nanoparticles on the intersected and multi-layered polymeric nanofibers. The diffusion and adsorption of glucose are expedited in the extended cavities and porosities of as-formulated polymeric nanofibers, maximizing the glucose utilization efficacy, while the uniformly implanted Co⁴⁺/Fe³⁺ active centers on PVdF-HFP nanofibers maximize the electrocatalytic activity toward glucose oxidation under alkaline regimes. Thus, the combinative sorts including nanofiber and nanocomposite strategies of PVdF-HFP/Co–Fe membrane assimilate the enzyme-less electrochemical glucose detection concerts of high sensitivity (375.01 μA mM^?1 cm^?2), low limit of detection (0.65 μm), and wide linear range (0.001 to 8 mM), outfitting the erstwhile enzyme-less glucose detection reports. Additionally, the endowments of high selectivity and real sample glucose-sensing analyses of PVdF-HFP/Co–Fe along with the binder-less and free-standing characteristics construct the state-of-the-art paradigm for the evolution of affordable enzyme-less electrochemical glucose sensors.

     

Studies on crystal transition of polyamide 11 nanocomposites by variable-temperature X-ray diffraction

Polyamide I1 （PAll） and its nanocomposites with different organoclay loadings were prepared by melt-compounding and subsequent pelletizing. The crystal phase transitions of PAl 1 and its clay nanocomposites were investigated by variable-temperature X-ray diffraction. It was found that the Brill transition of the nanocomposite was 20 K higher than that of the neat PAl 1 for both heating and cooling processes. The PAl 1 d-spacings of the nanocomposites were observed to be smaller than those of the neat PAl 1 for melt crystallization. The constraints imposed by the addition of layered clay, restricting the thermal expansion of the polymer chains, are probably responsible for such a reduction of the d-spacing.     

ZIF-Induced d-Band Modification in a Bimetallic Nanocatalyst: Achieving Over 44 % Efficiency in the Ambient Nitrogen Reduction Reaction

The electrochemical nitrogen reduction reaction (NRR) offers a sustainable solution towards ammonia production but suffers poor reaction performance owing to preferential catalyst–H formation and the consequential hydrogen evolution reaction (HER). Now, the Pt/Au electrocatalyst d-band structure is electronically modified using zeolitic imidazole framework (ZIF) to achieve a Faradaic efficiency (FE) of >44 % with high ammonia yield rate of >161 μg mg_cat⁻¹ h⁻¹ under ambient conditions. The strategy lowers electrocatalyst d-band position to weaken H adsorption and concurrently creates electron-deficient sites to kinetically drive NRR by promoting catalyst–N₂ interaction. The ZIF coating on the electrocatalyst doubles as a hydrophobic layer to suppress HER, further improving FE by >44-fold compared to without ZIF (ca. 1 %). The Pt/Au-N_ZIF interaction is key to enable strong N₂ adsorption over H atom.     

Graphene Liquid Marbles as Photothermal Miniature Reactors for Reaction Kinetics Modulation

We demonstrate the fabrication of graphene liquid marbles as photothermal miniature reactors with precise temperature control for reaction kinetics modulation. Graphene liquid marbles show rapid and highly reproducible photothermal behavior while maintaining their excellent mechanical robustness. By tuning the applied laser power, swift regulation of graphene liquid marble’s surface temperature between 21–135 °C and its encapsulated water temperature between 21–74 °C are demonstrated. The temperature regulation modulates the reaction kinetics in our graphene liquid marble, achieving a 12‐fold superior reaction rate constant for methylene blue degradation than at room temperature.     

Density,conductance, transference numbers,and diffusion measurements in concentrated solutions of nickel chloride at 25°C

The Hittorf technique for measuring transference numbers has been modified to produce precise data in concentrated aqueous electrolyte solutions. Density, molar conductance, transference number, tracer-diffusion, and mutual diffusion data are reported for aqueous NiCl₂ solutions up to 4M concentration at 25°C.Visiting Fellow at the Australian National University on leave from the School of Chemical Sciences, Universiti Sains Malaysia, Penang, Malaysia.     

Displacement of fibrinogen from the air/aqueous interface by dilauroylphosphatidylcholine lipid

Fibrinogen (FB) and other serum proteins leak into the aqueous alveolar lining layer due to lung injuries. The adsorption of these serum proteins at the air/aqueous interface can produce higher surface tensions than the pulmonary lipids, and acute respiratory distress syndrome (ARDS) can ensue. By having a molecular adsorption mechanism, as compared to a particulate adsorption mechanism of other longer chain lipids, dilauroylphosphatidylcholine (DLPC) lipid can expel FB from the air/aqueous interface at 25 degrees C, in water or in phosphate-buffered saline, as proven by tensiometry (also at 37 degrees C), ellipsometry, and infrared reflection-absorption spectroscopy. Moreover, before FB is displaced by DLPC at the interface, there is a substantial initial enhancement in the FB adsorption, consistent with some interaction or binding of DLPC with FB to produce a more hydrophobic protein surface. After the FB molecules have been displaced by DLPC, or when DLPC has already adsorbed at the interface, FB molecules are less favored to adsorb near the DLPC monolayer with the lecithin headgroups facing toward them. The results have implications for possible uses of DLPC lipid in potential lung surfactant formulations in treating patients with ARDS.