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Nitric oxide (NO) is a very well-known indoor pollutant, and high concentrations of it in the atmosphere lead to acid rain. Thus, there is great demand for NO sensors that have the ability to work at room temperature. In this work, NiO/SnO2 heterostructures have been prepared via the polyol process and were tested against different concentrations of NO gas at room temperature. The structural and morphological characteristics of the heterostructures were examined using X-ray diffraction and scanning electron microscopy, respectively, while the ratio of NiO to SnO2 was determined through the use of energy-dispersive spectrometry. The effects of both pH and thermal annealing on the morphological, structural and gas-sensing properties of the heterostructure were investigated. It was found that the morphology of the heterostructures consisted of rod-like particles with different sizes, depending on the temperature of thermal annealing. Moreover, NiO/SnO2 heterostructures synthesized with pH = 8 and annealed at 900 °C showed a response of 1.8% towards 2.5 ppm NO at room temperature. The effects of humidity as well as of stability on the gas sensing performance were also investigated.

High molecular weight polyvinylpyrrolidone (PVP) and seeding conditions are considered to have important roles in the synthesis of AgNWs. In this work, we report a versatile synthesis of AgNWs in a salt-free environment and under Ar inert atmosphere using high molecular weight PVP and seeding step during the synthetic process. The high molecular weight PVP was found to efficiently promote the preparation of AgNWs via supporting the proper growth control of AgNWs on {111} facets and selective growth on {100} facets. The seeding step facilitates the formation of seeds such as multiple twinned nanoparticles (MTPs) and single crystal seeds, which promoted the feasible formation of AgNWs. The shape and size of the synthesized AgNWs were characterized by SEM and TEM. The crystalline nature of the synthesized AgNWs was characterized by HRTEM, SAED and XRD, and their LSPR peaks were confirmed by UV-Vis spectroscopy. The conductive properties of the synthesized AgNWs were determined by preparing their thin conductive film on a PET substrate. The prepared AgNWs thin films exhibited good sheet resistance.

The controlled synthesis and paramagnetic properties of nanosized Zn–Fe–O oxides have been researched by the polyol and the heat treatment processes designed according to drying, annealing, and sintering from low to high temperatures. The structural changes have led to change weak superparamagnetism of nanosized Zn–Fe–O oxides in the forms of hybrid nanosized ZnO/ZnFe 2 O 4 oxides into paramagnetism of nanosized ZnFe 2 O 4 when the as-prepared samples of both ZnO and ZnFe 2 O 4 oxides were isothermally annealed and sintered from low temperature at about 60 °C to high temperature at 950 °C for 2 h during their structural phase transitions in all the measurements of x-ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM) and SEM/energy dispersive X-ray spectroscopy (EDX) combined methods. Interestingly, it is experimentally confirmed that one original paramagnetic hysteresis consists of paramagnetic segments and closed curves. Both normal and abnormal paramagnetic properties of ZnFe 2 O 4 were carefully investigated.

The equilibrium FeNi alloy exhibits the bcc phase in a narrow composition less than 5 at.% Ni. Fe 64 Ni 36 was obtained through instant chemical reduction employing polyol process and compared with Fe 5 Ni 95 alloy. X-ray diffraction revealed bcc and fcc phases for the Fe-rich and Ni-rich FeNi compositions, respectively. The metastable bcc FeNi transformed to the fcc phase on annealing at 700 °C, whereas the Ni-rich alloy retained its fcc phase. Electron microscopic examination revealed spherical morphology for Fe 64 Ni 36 alloy with an average size of 72 nm compared with flake-like morphology for the Fe 5 Ni 95 . The thermomagnetic analysis revealed a Curie temperature of 567 and 359 °C for the as-synthesized Fe and Ni-rich phases, respectively. An increase in Curie temperature by 30 °C was observed in both the compositions on annealing. Room temperature hysteresis loop measurements showed a saturation magnetization of 117 emu/g for bcc Fe 64 Ni 36 alloy which increased to 165 emu/g for the fcc Fe 64 Ni 36 . The reaction kinetics involved in polyol process has enabled us to synthesis and investigate the magnetic properties of metastable bcc phase in the Fe 64 Ni 36 composition.

Core–shell magnetic nanoparticles exhibit exchange bias, whereas the magnitude of the exchange bias field is influenced by various factors that are still under investigation. We present a detailed analysis of the magnetic behavior in Fe- and Co-rich FeCo particles with a ferrimagnetic oxide shell. The as-synthesized alloys, with an average particle size above 150 nm, show high saturation magnetization and exhibit multidomain nature. The magnetic behavior has been analyzed through first order reversal studies at room temperature, and low temperature (15 K) for the as-synthesized and size-reduced alloys. The size-reduced alloys exhibit exchange bias that enhances with decreasing average particle size and found to be maximum for the Co-rich FeCo. First order reversal curve (FORC) studies could resolve the reversible, irreversible magnetization components, and magnetostatic interactions. The low-temperature field cooled measurements expose random field bias acting at the interfaces. The studies reveal that FORC could be utilized to obtain information about particle size and its distribution dependent magnetic behavior in core–shell nanostructures.

Synthesizing intermetallic phases containing noble metals often poses a challenge as the melting points of noble metals often exceed the boiling point of bismuth (1560 °C). Reactions in the solid state generally circumvent this issue but are extremely time consuming. A convenient method to overcome these obstacles is the co‐reduction of metal salts in polyols, which can be performed within hours at moderate temperatures and even allows access to metastable phases. However, little attention has been paid to the formation mechanisms of intermetallic particles in polyol reductions. Identifying crucial reaction parameters and finding patterns are key factors to enable targeted syntheses and product design. Here, we chose metastable γ‐BiPd as an example to investigate the formation mechanism from mixtures of metal salts in ethylene glycol and to determine critical factors for phase formation. The reaction was also monitored by in situ X‐ray diffraction using synchrotron radiation. Products, intermediates and solutions were characterized by (in situ) X‐ray diffraction, electron microscopy, and UV‐Vis spectroscopy. In the first step of the reaction, elemental palladium precipitates. Increasing temperature induces the reduction of bismuth cations and the subsequent rapid incorporation of bismuth into the palladium cores, yielding the γ‐BiPd phase. The formation of γ‐BiPd in a polyol process has been monitored by X‐ray powder diffraction, light scattering, and in situ measurements of redox potential and pH value. Palladium nanoparticles are formed as primary reaction product followed by a successive reduction of bismuth cations and a diffusion‐controlled formation of the intermetallic target phase.

A simple and environment-friendly approach to prepare zinc oxide nanoaggregates was achieved by employing ethylene glycol–H2O as the reaction medium. The composition and structure of the as-fabricated ZnO products were confirmed using X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and nitrogen adsorption measurements. By tailoring the volume ratio of ethylene glycol to water, coral-like, flower-like, and nanoparticulate ZnO nanoaggregates were successfully synthesized. The impact of the structure of the as-obtained ZnO nanoaggregates on the photocatalytic degradation of ciprofloxacin was further studied. Under simulated solar light irradiation, the photocatalytic removal rate of coral-like, flower-like, and nanoparticulate ZnO nanoaggregates for ciprofloxacin was 45%, 80%, and 90%, respectively. The reactive species trapping experiment result indicated that the generated holes, OH−, and ·O2− active species mainly contributed to the degradation of ciprofloxacin. On the basis of photoluminescence spectra and photo/electrochemical measurement results, the prevention of electron-hole recombination and the rapid charge transfer upon the ZnO nanoparticle aggregates resulted in their efficient photocatalytic activity.

In our review, we have presented a summary of the research accomplishments of nanostructured multimetal-based electrocatalysts synthesized by modified polyol methods, especially the special case of Pt-based nanoparticles associated with increasing potential applications for batteries, capacitors, and fuel cells. To address the problems raised in serious environmental pollution, disease, health, and energy shortages, we discuss and present an improved polyol process used to synthesize nanoparticles from Pt metal to Pt-based bimetal, and Pt-based multimetal catalysts in the various forms of alloy and shell core nanostructures by practical experience, experimental skills, and the evidences from the designed polyol processes. In their prospects, there are the micro/nanostructured variants of hybrid Pt/nanomaterials, typically such as Pt/ABO3-type perovskite, Pt/AB2O4-type ferrite, Pt/CoFe2O4, Pt/oxide, or Pt/ceramic by modified polyol processes for the development of electrocatalysis and energy technology. In the future, we suggest that both the polyol and the sol-gel processes of diversity and originality, and with the use of various kinds of water, alcohols, polyols, other solvents, reducing agents, long-term capping and stabilizing agents, and structure- and property-controlling agents, are very effectively used in the controlled synthesis of micro/nanoparticles and micro/nanomaterials. It is understood that at the levels of controlling and modifying molecules, ions, atoms, and nano/microscales, the polyol or sol-gel processes, and their technologies are effectively combined in bottom-up and top-down approaches, as are the simplest synthetic methods of physics, chemistry, and biology from the most common aqueous solutions as well as possible experimental conditions.

In this research, we have mainly focused on the controlled synthesis, and properties of micro/nanosized ferrite and hexaferrite powders by the polyol process. They are Fe3O4-type Sr-Fe-O oxide and SrFe12O19 with the structure and magnetic properties by SEM, XRD, and VSM measurements. After heat treatment, it was discovered that Sr element was gradually fully incorporated into Fe3O4 for the formation of the original hexaferrite structure of SrFe12O19 at 950°C.