Correlation between the particle size, structural and photoluminescence spectra of nano NiCr2O4 and La doped NiCr2O4 materials

Nano NiCr2O4 undoped and La doped NiCr2O4 nanorods array were successfully prepared by solution based conventional method[sbcm]. The synthesized samples were characterized by the diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) spectroscopy for finding optical properties. Further, the samples structure confirmed by Fourier transforms infrared (FTIR), and X-ray diffraction (XRD)techniques. High-resolution transmission electron microscopy (HRTEM) analysis revealed the attachment of NiCr2O4 nanorods on surface of nanoparticles. From the results, it was found that the reaction time, band gap energy, and particle size strongly influenced by changing the concentration of La in NiCr2O4. This work is notable for its examination of the impact of the precursor on the optical and structural characteristics of samples of La-doped and undoped NiCr2O4. This was the first time the investigation had been done. The average particle size of the La-doped and undoped NiCr2O4 samples is between 16 and 24 nm.

Enhancement of the structure, solar cells and vibrational studies of undoped CuCr2O4 and La-doped CuCr2O4 semiconductor compounds

In the present paper, we report the successful synthesis of spinel-type of CuCr₂O₄ and La doped CuCr₂O₄ semiconductor nanoparticles by a microwave method. Starting with the precursor complex, this technique includes the creation of homogenous solid intermediates, which reduces atomic diffusion pathways during the microwave process. CuCr₂O₄ and La doped CuCr₂O₄ were characterized by the following analytical methods for instance X-ray diffraction (XRD), transmission electron microscopy (TEM), Ultraviolet–visible (UV–Vis) spectroscopy and Fourier transform infrared spectroscopy (FTIR). The results demonstrated that modifying the precursor had a significant impact on the size, solar cell size, as well as reaction period of synthesizing CuCr₂O₄ and La doped CuCr₂O₄. The impacts of precursors on the morphological and structural characteristics of CuCr₂O₄ and La doped CuCr₂O₄ were examined for the first time in this publication.

Recent advances in the synthesis and applications of mordenite zeolite - review

Among the many industrially important zeolites, mordenite is found to be interesting because of its unique and exceptional physical and chemical properties. Mordenite (high silica zeolite) is generally prepared by the hydrothermal method using TEA+ cations. TEA+ cations are the best templating agent, though they can create a number of issues, for instance, generating poison and high manufacturing cost, wastewater contamination, and environmental pollution. Hence, it is necessary to find a mordenite synthesis method without using an organic template or low-cost template. In this review, a number of unique sources were used in the preparation of mordenite zeolite, for instance, silica sources (rice husk ash, silica gel, silica fumes), alumina sources (metakaolin, faujasite zeolite) and sources containing both silica and alumina (waste coal fly ash). These synthesis approaches are also based on the absence of a template or low-cost mixed organic templates (for instance, glycerol (GL), ethylene glycol (EG), and polyethylene glycol 200 (PEG)) or pyrrolidine-based mesoporogen (N-cetyl-N-methylpyrrolidinium) modifying the mordenite framework which can create unique properties. The framework properties and optical properties (indium-exchanged mordenite zeolite) have been discussed. Mordenite is generally used in alkylation, dewaxing, reforming, hydrocracking, catalysis, separation, and purification reactions because of its large pore size, strong acidity, and high thermal and chemical stability, although the applications are not limited for mordenite zeolite. Recently, several applications such as electrochemical detection, isomerization, carbonylation, hydrodeoxygenation, adsorption, biomass conversion, biological applications (antibacterial activity), photocatalysis, fuel cells and polymerization reactions using mordenite zeolite were explored which have been described in detail in this review.

Activated Graphite Supported Tunable Au-Pd Bimetallic Nanoparticle Composite Electrode for Methanol Oxidation

Methanol (CH₃OH) is a favorable fuel for direct methanol fuel cells (DMFCs) in compact devices. This work, we present a facile and simple approach to make divergent molar ratios uniform gold (Au) and palladium (Pd) nanoparticles (NPs) decoration on an activated graphite (AGR) electrode. The binary combination of these AGR/Au-Pd catalysts composition is controlled by modifying the molar ratio of the Au and Pd precursors. The AGR/Au-Pd composite was characterized by suitable microscopy and spectroscopy characterization technique. Electrochemical studies of the prepared material were also conducted by chronoamperometry (CA) and cyclic voltammetry (CV) methods. The AGR/Au-Pd composite nanoparticles were successfully prepared and decorated on an activated screen-printed carbon electrode (ASPCE) surface. The ASPCE/AGR/Au-Pd electrode has great potential and stability for DMFCs. The prepared modified electrode was compared by a Pt/C electrode, and its efficiency was better than those of previously reported modified electrodes. Additionally, the electrocatalytic reaction of methanol oxidation is a surface controlled process on the electrode surface.

Reduced Graphene Oxide/Multiwalled Carbon Nanotube Composite Decorated with Fe₃O₄ Magnetic Nanoparticles for Electrochemical Determination of Hydrazine in Environmental Water

In the present work, a reduced graphene oxide and multiwalled carbon nanotube (RGO/MWCNTFe₃O₄) composite decorated with Fe₃O₄ magnetic nanoparticles was prepared as an electrochemical sensor. The surface morphology of the prepared composite was identified by scanning electron microscopy and X-ray diffraction. The electrochemical properties of the GCE/RGO/MWCNT-Fe₃O₄ electrode were investigated by electrochemical impedance spectroscopy, cyclic voltammetry and amperometry. The GCE/RGO/MWCNT-Fe₃O₄ electrode exhibited higher electrocatalytic performance towards the oxidation of hydrazine. In the optimal conditions, the GCE/RGO/MWCNT-Fe₃O₄ electrode showed a wide linear range (0.15-220 μM), low limit of detection (LOD) (0.75 μM), and high sensitivity (2.868 μA μM^-1 cm^-2). The prepared GCE/RGO/MWCNT-Fe₃O₄ electrode also had excellent repeatability, selectivity, and reproducibility. The practical application of the electrode was confirmed with various spiked water samples and demonstrated acceptable recovery.

Combustion and emission analysis of hydrogenated waste polypropylene pyrolysis oil blended with diesel

Petroleum-based plastic pyrolysis oil contains unsaturated compounds, and the presence of these compounds makes the produced fuel unsuitable for combustion in diesel engines. Hydrogenation of pyrolysis oil is performed to convert unsaturated compounds to saturated compounds. Past studies have shown that hydrogenation of petroleum-based plastic pyrolysis oil is viable; however, its combustion and emissions analysis in diesel engines has not yet been reported. In this study, we investigated the combustion, performance, and emissions of hydrogenated polypropylene pyrolysis oil (HPPO) blended with diesel. Polypropylene (PP) was converted to pyrolysis oil using ZSM-5 as the catalyst. The hydrogenation of polypropylene pyrolysis oil (PPO) was conducted at pressure of 70 bar, and the reaction temperature was maintained at 350 °C. Ni metal impregnated on the ZSM-5 base support was used as the catalyst of choice. The produced HPPO possessed physicochemical properties that match the EN590 standards(European diesel fuel standards). Gas chromatography-mass spectrometry (GC-MS) studies of PPO and HPPO showed the effectiveness of hydrogenation for the complete conversion of alkenes to alkanes, and hydrocracking resulted in cracking higher carbon number alkanes to lower values. HPPO was blended with diesel in ratios of 10 wt.%, 20 wt.%, 30 wt.%, and 40 wt.%. The diesel engine performance results for the blended fuel showed combustion, performance, and emissions on par with pure diesel fuel for blending ratios up to 20 wt.%. As is known, plastic solid waste (PSW) materials pose serious hazards to the environment. Our HPPO physicochemical properties matched the EN590 standards for diesel fuel. The combustion of HPPO in diesel engines can provide an option for environmentally cleaner disposal of PSW.

Facile synthesis of core-shell nanocomposites Au catalysts towards abatement of environmental pollutant Rhodamine B

Magnetically recoverable Au nanoparticles immobilized/stabilized on core-shell nanocomposites are synthesized by the combination of suspension polymerization as well as surface initiator atom transfer radical polymerization (SI-ATRP) methods. The magnetic core-shell supported Au nanocatalysts are namely Fe₃O₄-PAC-AuNPs, Fe₃O₄-PVBC-g-PAC-AuNPs, Fe₃O₄-HEA-AuNPs, and Fe₃O₄-PVBC-g-HEA-AuNPs. Among all the catalysts, Fe₃O₄-PVBC-g-PAC-Au NPs exhibited an excellent activity in the reduction of Rhodamine B with an apparent rate constant of 10.77 × 10^-3 s^-1 and TOF value of 47.62 × 10^-3 s^-1 under pseudo-first order reaction condition. Further, Fe₃O₄-PVBC-g-PAC-Au NPs has an outstanding activity and recyclability without applying any external magnetic field. This new approach provides an exciting potential way in the preparation of recyclable metal nano-catalysts with high catalytic activity.

Reduced graphene oxide/gold tetraphenyl porphyrin (RGO/Au–TPP) nanocomposite as an ultrasensitive amperometric sensor for environmentally toxic hydrazine

A gold tetra phenyl porphyrin/reduced graphene oxide (RGO/Au–TPP) nanocomposite film modified glassy carbon electrode (GCE) was prepared for the trace level detection of hydrazine.

A non-covalent interaction of Schiff base copper alanine complex with green synthesized reduced graphene oxide for highly selective electrochemical detection of nitrite

A novel and selective nitrite sensor based on non-covalent interaction of Schiff base copper complex [Cu(sal-ala)(phen)] with reduced graphene oxide (RGO) was developed by simple eco-friendly approach.