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Morphological Evolution Induced through Heterojunction of W-decorated NiO Nanoigloos: Synergistic Effect on High-performance Gas Sensors
摘要： Morphological evolution accompanying a surface roughening and the preferred orientation is an effective way to realize a high-performance gas sensor because of its significant potential as a chemical catalyst by chemical potentials and atomic energy states. In this work, we investigated the heterojunction of both-sided W-decorated NiO nanoigloos fabricated through RF sputtering and a soft-template method. Interestingly, the morphological evolution characterized by a pyramidal rough surface and the preferred orientation of the (111) plane was observed upon decorating the bare NiO nanoigloos with W. The underlying mechanism of the morphological evolution was precisely demonstrated based on a van der Drift competitive growth model originating from the oxygen transport and chemical strain in a lattice. The gas sensing properties of W-decorated NiO show an excellent NO2 response and selectivity when compared to other gases. In addition, high response stability was evaluated under interference gas and humidity condition. The synergistic effects on the sensing performance were interpreted based on the morphological evolution of W-decorated NiO nanoigloos.
关键词： Gas sensor,Nanostructure,Morphological evolution,Heterojunction,NO2
更新于2025-09-19 17:15:36
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Morphological evolution of upconversion nanoparticles and their biomedical signal generation
摘要： Advancements in the fabrication of upconversion nanoparticles (UCNPs) for synthetic control can enable a broad range of applications in biomedical systems. Herein, we experimentally verified the role of the hydrothermal reaction (HR) time in the synthesis of NaYF4:20%Yb3+/3%Er3+ UCNPs on their morphological evolution and phase transformation at different temperatures. Characterizations of the as-prepared UCNPs were conducted using X-ray diffraction (XRD), electron microscopy and spectroscopy, and thermogravimetric and upconversion (UC) luminescence analysis. We demonstrated that determining the optimal HR time, also referred to here as the threshold time, can produce particles with good homogeneity, hexagonal phase, and UC luminescence efficiency. Subsequently, the polymer coated UCNPs maintained their original particle size distribution and luminescence properties, and showed improved dispersibility in a variety of solvents, cellular nontoxicity, in vitro bioimaging, and biocompatibility as compared to the bare UCNP. Besides this, polyacrylic acid conjugated UCNPs (UCNP@PAA) also revealed the strong anticancer effect by conjugating with doxorubicin (DOX) as compared to the free DOX. Based on these findings, we suggest that these particles will be useful in drug-delivery systems and as in vivo bioimaging agents synchronously.
关键词： phase transformation,morphological evolution,biomedical applications,hydrothermal reaction,upconversion nanoparticles
更新于2025-09-09 09:28:46
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Investigation of sintering kinetics and morphological evolution of silver films from nano-dispersion
摘要： The present study aimed at investigating the sintering kinetics and the mechanism of achieving uniform film morphology from silver nano-dispersion through evaporation of the solvent. A tuned time elapse between drop casting of silver dispersion and the annealing (dwell-time) acted as the decision maker in engineering the morphology: ring stain (infinite dwell-time), uniform deposit (variable dwell-time) and dot formation (zero dwell-time). Three distinct dwell-times (10, 20 and 30 min) are chosen for the study at different temperatures (120 to 250 °C) and the conclusion is derived based on the profile of the deposit. The frozen morphology that resulted from the evaporation goes through the debonding of surfactant with simultaneous sintering to minimize the surface energy. A linear isothermal sintering model comprising initial grain size, grain growth parameter, annealing time and fractional porosity helps to predict the grain size post-annealing. Theoretical predictions of grain sizes are well matched with experimental ones. The grain growth parameter which shows an upward trend with the annealing temperature is mainly due to a reduction in the porosity and the increase in the fraction of solid–solid interface which shows betterment in the percolation paths available for the movement of carriers.
关键词： sintering kinetics,dwell-time,silver films,nano-dispersion,morphological evolution
更新于2025-09-09 09:28:46