In this study we present modifications in a phonon confinement model in order to obtain a better description for the Raman spectra of spherical nanocrystals, namely: bare-core, core–shell, and core–multishell. Our new interpretations allow investigating the influences of the interfacial alloying and strain effects on the vibrational spectra of core–shell nanocrystals. The robustness of the modified phonon confinement model was confirmed by precisely describing the Raman spectra of wurtzite CdSe/CdS core–shell magic-sized quantum dots (CS-MSQDs) synthesized directly in aqueous solution by a new route. The CdSe MSQD sample was used as template to growth CdSe/CdS CS-MSQDs with different shell thickness by setting the synthesis temperature. By using our modified model to fit the Raman spectra of samples, we have obtained the size dimensions of CS-MSQDs (core-diameter and shell-thickness), in excellent agreement with the values obtained by the atomic force microscopy results, confirming that the change in the synthesis temperature is a simple and efficient way to control the CdS-shell thickness during the growth process. Furthermore, we have confirmed the formation of an alloy layer (CdS x Se1‑x ) at the interface of these CdSe/CdS CS-MSQDs and that the strain effects can be neglected for the wurtzite structure.

In this study, we report on the synthesis of CdSe/CdS core-shell ultrasmall quantum dots (CS-USQDs) using an aqueous-based wet chemistry protocol. The proposed chemical route uses increasing concentration of 1-thioglycerol to grow the CdS shell on top of the as-precipitated CdSe core in a controllable way. We found that lower concentration of 1-thioglycerol (3 mmol) added into the reaction medium limits the growth of the CdSe core, and higher and increasing concentration (5-11 mmol) of 1-thioglycerol promotes the growth of CdS shell on top of the CdSe core in a very controllable way, with an increase from 0.50 to 1.25 nm in shell thickness. The growth of CS-USQDs of CdSe/CdS was confirmed by using different experimental techniques, such as optical absorption (OA) spectroscopy, fluorescence spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. Data collected from OA were used to obtain the average values of the CdSe core diameter, whereas Raman data were used to assess the average values of the CdSe core diameter and CdS shell thicknesses.

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Zn 1−x Mn x O nanostructures were synthesized via the microwave-assisted hydrothermal method, which rapidly produces particles of controlled size and morphology. Samples were analyzed considering the effects of manganese ion concentration. XRD revealed that all samples had wurtzite-type structure with Mn 2+ ions incorporated in the oxide lattice. UV−vis spectra showed absorption bands from the d−d transitions of Mn 2+ ions. As the doping concentration increased, the value of the energy gap decreased, indicating intermediary energy levels within the band gap in the Mn-doped ZnO samples. All samples produced broadband photoluminescence (PL) emissions in the yellow−orange− red range. Additionally, the PL intensity decreased with Mn 2+ ion incorporation into the ZnO lattice due to the creation of new recombination centers. Microscopy images showed that manganese in the ZnO matrix produced homogeneously distributed nanostructures. EPR results indicated two locations of Mn 2+ ions in the ZnO lattice, lower concentrations in the core of the lattice and higher concentrations at the surface.

Nanostructured materials have exhibited great potential applications in the field of (bio)sensing. In particular, the capacitive electrolyte‐insulator‐semiconductor (EIS) sensor is a suitable field‐effect device for integration of film‐based nanostructures as sensing units. In this study, the fabrication of a hybrid nanostructured film using the layer‐by‐layer (LbL) technique combining cobalt ferrite (CoFe2O4) nanocrystals complexed with poly(vinylpyrrolidone) (PVP) and embedded with a poly(amidoamine) (PAMAM) dendrimer is investigated. LbL films containing a PAMAM/PVP‐CoFe2O4 architecture with different bilayers are fabricated onto EIS chips of Al/p‐Si/SiO2. The morphology of the films is characterized by atomic force microscopy (AFM) and the sensing properties toward H2O2 detection are evaluated by capacitance–voltage (C/V) and constant capacitance (ConCap) measurements. By correlating the electrochemical and morphological properties of the films, the findings lead to an optimized system, in which the best performance is observed for a 3‐bilayer EIS‐(PAMAM/PVP‐CoFe2O4) sensor, exhibiting a sensitivity of ca. 26.5 mV decade−1 and limit of detection of ca. 157 × 10–6 m toward H2O2. The set‐up presents for the first time a field‐effect sensor for H2O2 detection as an alternative to conventional amperometric H2O2 sensors.

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