Assorted analytical and spectroscopic techniques for the optimization of the defect-related properties in size-controlled ZnO nanowires

Synergistic Behavior of Polyethyleneimine and Epoxy Monomers Loaded in Mesoporous Silica as a Corrosion-Resistant Self-Healing Epoxy Coating

Corrosion is a significant problem and is, to a large extent, responsible for the degradation of metallic parts. In this direction, mesoporous silica particles (MSPs) were synthesized by a sol-gel technique and had an average pore diameter of ∼6.82 nm. The MSPs were loaded with polyethyleneimine (PEI) and epoxy monomers and, after that, carefully mixed into the epoxy matrix to formulate new modified polymeric coatings. The microstructural, compositional, structural, and thermal properties were investigated using various characterizing tools [Transmission electron microscopy, Fourier transform infrared spectroscopy, hermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy]. TGA confirms the loading of mesoporous silica with a corrosion inhibitor, and its estimated loading amount is ∼8%. The electrochemical impedance spectroscopy properties of the reference and modified coated samples confirm the promising anti-corrosive performance of the synthesized polymeric smart coatings. Localized electrochemical tests (scanning vibrating electrode technique and scanning ion-selective electrode technique) evidence the corrosion inhibition ability of the coating, and its self-healing was also observed during 24 h of immersion. The decent anti-corrosion performance of the modified coatings can be credited to the efficient synergistic effect of the PEI and epoxy monomer.

Chemoselective hydrogenation of cinnamaldehyde over a tailored oxygen-vacancy-rich Pd@ZrO2 catalyst

Selective hydrogenation of cinnamaldehyde to hydrocinnamaldehyde is captivating due to its industrial relevance.

Defect-Engineered Nanostructured Ni/MOF-Derived Carbons for an Efficient Aqueous Battery-Type Energy Storage Device

A Ni-based metal-organic framework (Ni-MOF) has been synthesized using a microwave-assisted strategy and converted to nanostructured Ni/MOF-derived mesoporous carbon (Ni/MOFDC) by carbonization and acid treatment (AT-Ni/MOFDC). The materials are well characterized with Raman, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and Brunauer-Emmett-Teller (BET), revealing that chemical etching confers on the AT-Ni/MOFDC-reduced average nanoparticle size (high surface area) and structural defects including oxygen vacancies. AT-Ni/MOFDC displays low series resistances and a higher specific capacity (C _s) of 199 mAh g^-1 compared to Ni/MOFDC (92 mAh g^-1). This study shows that the storage mechanism of the Ni-based electrode as a battery-type energy storage (BTES) system can be controlled by both non-faradic and faradic processes and dependent on the sweep rate or current density. AT-Ni/MOFDC reveals mixed contributions at different rates: 75.2% faradic and 24.8% non-faradic contributions at 5 mV s^-1, and 34.1% faradic and 65.9% non-faradic at 50 mV s^-1. The full BTES device was assembled with AT-Ni/MOFDC as the cathode and acetylene black (AB) as the anode. Compared to recent literature, the AT-Ni/MOFDC//AB BTES device exhibits high energy (33 Wh kg^-1) and high power (983 W kg^-1) with excellent cycling performance (about 88% capacity retention over 2000 cycles). This new finding opens a window of opportunity for the rational designing of next-generation energy storage devices, supercapatteries, that combine the characteristics of batteries (high energy) and supercapacitors (high power).

The effect of silver oxidation on the photocatalytic activity of Ag/ZnO hybrid plasmonic/metal-oxide nanostructures under visible light and in the dark

A new synergetic hybrid Ag/ZnO nanostructure was fabricated which is able to cause photocatalytic degradation (in high yields) of methylene blue under visible light as well as in the dark. In this nanostructure, ZnO was synthesized using the arc discharge method in water and was coupled with Ag via a chemical reduction method. X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy results confirmed the existence of defects in ZnO in the hybrid nanostructures; these defects act as electron traps and inhibit the recombination of electron-hole pairs. The absorption edge of the hybrid nanostructure shifts toward the visible region of the spectrum due to a combination of the Ag plasmonic effect and the defects in ZnO. Band-edge tuning causes effective visible light absorption and enhances the dye degradation efficiency of Ag/ZnO nanostructures. Silver oxidation in the hetero-structure changed the metal-semiconductor interface and suppressed the plasmonic enhancement. Nevertheless, the synthesized Ag/ZnO decomposed methylene blue in visible light, and the silver oxidation only affected the catalytic activity in the dark. This work provides insight into the design of a new and durable plasmonic-metal oxide nanocomposite with efficient dye degradation even without light illumination.

Compound Homojunction:Heterojunction Reduces Bulk and Interface Recombination in ZnO Photoanodes for Water Splitting

Photoelectrochemical water splitting is far more efficient thanks to the novel ZnOSe/ZnO/BZO thin-film photoanodes fabricated in this work. A novel structure is developed for simultaneously suppressing the charge recombination in the ZnO bulk and at the semiconductor-electrolyte interface. This structure achieves a five-fold enhancement in water-splitting performance, compared to that of pristine ZnO photoanodes, when illuminated using visible light.

Novel green phosphorescence from pristine ZnO quantum dots: tuning of correlated color temperature

Creating novel functionality is always fascinating as well as advantageous from a device point of view.

Synthesis and field emission properties of different ZnO nanostructure arrays

In this article, zinc oxide (ZnO) nanostructures of different shapes were fabricated on silicon substrate. Well-aligned and long ZnO nanowire (NW) arrays, as well as leaf-like ZnO nanostructures (which consist of modulated and single-phase structures), were fabricated by a chemical vapor deposition (CVD) method without the assistance of a catalyst. On the other hand, needle-like ZnO NW arrays were first fabricated with the CVD process followed by chemical etching of the NW arrays. The use of chemical etching provides a low-cost and convenient method of obtaining the needle-like arrays. In addition, the field emission properties of the different ZnO NW arrays were also investigated where some differences in the turn-on field and the field-enhancement factors were observed for the ZnO nanostructures of different lengths and shapes. It was experimentally observed that the leaf-like ZnO nanostructure is most suitable for field emission due to its lowest turn-on and threshold field as well as its high field-enhancement factor among the different synthesized nanostructures.