Fe-N/C Catalyst using Various Nitrogen and Carbon Ratio through Chemical Oxidative Polymerization

This study aims to explain the effect of variations in nitrogen and carbon composition of catalysts on electrochemical properties and physical characterization. The usage of non-precious metals supported by nitrogen-carbon is one alternative to reduce the amount of platinum as the innovation of energy materials. Iron is a transition metal that can increase catalytic activity with the addition of a nitrogen source. The polymerization process was carried out by chemical oxidative polymerization for 24 hours in an ice bath using aniline as N source. Optimization of nitrogen coating on the carbon surface is carried out by mixing carbon during polymerization. The mixing of iron precursor and N/C powder was carried out in an ultrasonic bath and continued with pyrolysis at a temperature of 700°C. Regarding Cyclic Voltammetry (CV) test, the Fe-N/C = 2/1 catalyst has the largest area and the highest current density. The presence of Fe2O3 is needed to improve the electrochemical properties compared to Fe3C compounds. The composition analysis showed that the Fe-N/C = 2/1 catalyst had the highest Fe content after pyrolysis. In addition, the Fe-N/C = 2/1 catalyst also had the highest nitrogen content which can form a nitrogen functional group from the pyrolysis process.

Synthesis of Magnetite Nanoparticles through a Lab-on-Chip Device

Magnetite nanoparticles (MNPs) represent one of the most intensively studied types of iron oxide nanoparticles in various fields, including biomedicine, pharmaceutics, bioengineering, and industry. Since their properties in terms of size, shape, and surface charge significantly affects their efficiency towards the envisaged application, it is fundamentally important to develop a new synthesis route that allows for the control and modulation of the nanoparticle features. In this context, the aim of the present study was to develop a new method for the synthesis of MNPs. Specifically, a microfluidic lab-on-chip (LoC) device was used to obtain MNPs with controlled properties. The study investigated the influence of iron precursor solution concentration and flowed onto the final properties of the nanomaterials. The synthesized MNPs were characterized in terms of size, morphology, structure, composition, and stability. Results proved the formation of magnetite as a single mineral phase. Moreover, the uniform spherical shape and narrow size distribution were demonstrated. Optimal characteristics regarding MNPs crystallinity, uniformity, and thermal stability were obtained at higher concentrations and lower flows. In this manner, the potential of the LoC device is a promising tool for the synthesis of nanomaterials by ensuring the necessary uniformity for all final applications.

Green biosynthesis and physicochemical characterization of Fe3O4 nanoparticles using Punica granatum L. fruit peel extract for optoelectronic applications

Green biosynthesis of Fe3O4 nanoparticles (NPs) using plant extract is desired, as the plant extract is safe for humans and the environment. In this study, magnetite Fe3O4 NPs were greenly prepared using Punica granatum L. fruit peel extract as a reducing and capping agent. The effect of iron precursor contraction (0.01–0.1 M, FeCl3) was studied. The Fe3O4 crystalline with an average crystallite size range from 21 to 23 nm was proven by X-ray powder diffraction. Scanning electron microscopy images showed that the synthesized Fe3O4 NPs were mostly cubical. Ultraviolet-visible spectra showed that the prepared Fe3O4 NPs exhibit absorption at 270 nm related to the Fe3O4 NPs with a direct bandgap ranging from 1.87 to 2.26 eV and indirect bandgap of 2.16–2.48 eV. Fourier transform infrared spectroscopy analysis showed two characteristic absorption bands at 515 and 567 cm−1, which proved the successful formation of Fe3O4. The proposed method using Punica granatum L. fruit peel extract offers an economical and environmentally friendly route for synthesizing many other types of metal oxides.

Band Gap Tuning of Photo Fenton-like Fe3O4/C Catalyst through Oxygen Vacancies for Advanced Visible Light Photocatalysis

In this contribution, low-cost Fe3O4/C nanocomposites has been targeted by a simplistic single-pot D-glucose mediated hydrothermal reduction method using a single iron precursor (FeCl3. 6H2O) acquired from accumulated iron ore...