Dialkylamide as Both Capping Agent and Surfactant in a Direct Solvothermal Synthesis of Magnetite and Titania Nanoparticles

Abstract

An ecofriendly, low-cost, one-pot solvothermal approach has been developed to prepare spherical magnetite nanoparticles with sizes in the 7−12 nm range capped with a dialkylamine. Iron isopropoxide, water vapor, absolute ethanol, oleic acid, and oleylamine were used as iron oxide precursor, hydrolysis agent, solvent and surfactants, respectively. The surfactants' role was investigated and an accurate correlation among the synthetic parameters, the crystallographic phases, and both crystallite and particle size was found. The amounts of oleylamine and oleic acid and the temperature have been revealed to be the key parameters in order to tune particle size and their polydispersity. An in-depth study on the role of each surfactant has pointed out the fundamental role of the amine as a reduction promoter as demonstrated by using different amines and confirmed by Mossbauer measurements. A dual 1 H NMR-Fourier transform infrared spectroscopy approach on selected experiments for the investigation of the capping agents (in the presence of a magnetic phase (Magnetite) or a diamagnetic one (Anatase) prepared in the same synthetic conditions) has been found to be fundamental to clarify the actual nature of the capping agent of the nanoparticles and the reactions involved between the surfactants. New insights on the reaction mechanism confirm the formation of an amide that represents a new cosurfactant for the size and shape regulation and a biocompatible molecular coating of magnetite and anatase nanoparticles.

Ligand & band gap engineering: tailoring the protocol synthesis for achieving high-quality CsPbI3 quantum dots

“…Moreover, the appearance of a new peak at  7.1 ppm is associated to the formation of an amide as the product of the condensation reaction (denoted as *''). 21,42 This result is in good agreement with the decrease of the signal associated to ammonium group at 8.6 ppm ( Figure 2b). In order to confirm the formation of the amide, we intentionally synthesized N-oleyl-oleamide (NOA) by mixing OA and OLA at 190 °C 38 under vacuum overnight and characterized by 1 H and 13 C NMR the final product ( Figure S1a).…”

On the synthesis of bi-magnetic manganese ferrite-based core–shell nanoparticles

“…Room temperature 57 Fe Mössbauer spectroscopy was performed on a Wissel spectrometer using transmission arrangement and proportional detector LND-45431. An α-Fe foil was used as a standard, and the fitting procedure was done by NORMOS program to determine the isomer shift, quadrupole splitting, hyperfine field, and full width at half maximum of the signals.…”

“…Structural and magnetic properties of MnA, Mn@Fe1, and MnA@Co were studied through 57 Fe Mössbauer spectroscopy, at room temperature (RT) and DC magnetometry (Figure 5). At RT, the sample MnA shows a singlet, accounting for nanoparticles in the superparamagnetic state, having isomer shift of 0.32 mm/s, typical of Fe III .…”

Effect of Particle Size on the Performance of TiO2 Based Dye‐Sensitized Solar Cells

“…However, the choice of capping agent for nanoparticles synthesis is very crucial, because the capping agents often influence various properties of the nanoparticles, including its size, shape and interactions behavior with the surrounding solvent molecules . It is well established that the properties of TiO 2 materials are highly dependent on its size, morphology, specific surface area, composition, crystallinity and porosity for various applications including DSSCs ,. Various types of capping agents including hetero‐atom‐functionalized long‐chain hydrocarbons, such as oleic acid (OA), oleylamine (OAm), octadecylamine (ODA),trioctylphosphine (TOP), triphenyl phosphine (TPP), dodecanethiol (DDA) etc, and polymers such as polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), polyethylene glycol (PEG), poly propylene glycol (PPG), polyacrylic acid (PAA), polyphenylene oxide (PPO), were used for controlling the size and achieving monodispersibility of nanoparticles .…”