Multi-Active Sites Loaded NiCu-MOF@MWCNTs as a Bifunctional Electrocatalyst for Electrochemical Water Splitting Reaction.

Water can be sustainably and ecologically converted by electrocatalysts into hydrogen and oxygen, which, in turn, can be converted into energy. However, the advancement of using water as green energy is hampered by limitations in the study of high-performance catalysts. The purpose of this study was to construct an electrocatalyst by anchoring well-dispersed multiwalled carbon nanotubes (MWCNTs) on nickel-copper (NiCu-MOF) nanoblocks through a simple solvothermal method. The synthesis of NiCu-MOF@MWCNTs demonstrated exceptional electrocatalytic performance for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline medium. At 10 mA cm-2 in 1.0 M KOH, the OER and HER performance of the catalyst displays a relatively low overpotential, with only 220 and 78 mV, respectively. Furthermore, the catalytic activity remained unchanged for 24 h in 1.0 M KOH. This performance was superior to the majority of electrocatalysts that have been reported. This was achieved by utilizing the strong synergy that exists between MWCNTs and bimetallic (Ni-Cu) nano blocks present in the metal-organic framework. The enhanced electrocatalytic activity of the nanocomposite can be attributed to the synergistic impact caused by its various components.

Development of robust noble-metal free lanthanum, neodymium doped Li1.05Ni0.5Mn1.5O4 as a bifunctional electrocatalyst for electrochemical water splitting.

Catalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are at the heart of water oxidation reactions. Despite continuous efforts, the development of OER/HER electrocatalysts with high activity at low cost remains a big challenge. Herein, we report a composite material consisting of Li1.05Ni0.5Mn1.5O4, Li1.05Ni0.5 La0.10Mn1.40O4, and Li1.05Ni0.5 Nd0.10Mn1.40O4 as a bifunctional electrocatalyst for OER and HER applications. Though the catalyst has a modest activity for HER, it exhibits high OER activity thereby making it a better nonprecious electrocatalyst for both OER and HER. The catalytic activity arises from the synergetic effects between LNM-La and LNM-Nd by a facile route that shows excellent and durable bifunctional catalytic activity for OER and HER in the alkaline medium developed. The LNM, LNM-La, and, LNM-Nd displayed current densities of 2.17 V, 1.68 V, and 1.93 V vs. RHE at 10 mA cm-2 respectively. The Tafel slope values obtained for LNM, LNM-La, and LNM-Nd are about 419 mV dec-1, 118 mV dec-1, and 378 mV dec-1 respectively. These results indicate the superior electrocatalytic activity of LNM-La with facile OER kinetics.

Rational design of α-MnO2/HT-GCN nanocomposite for effective photocatalytic degradation of ciprofloxacin and pernicious activity.

The present study is mainly concerned with the development of cost-efficient composite material utilized to produce one-dimensional manganese oxide (α-MnO2) nanoparticles coated on two-dimensional graphitic carbon nitrides (HT-GCN) as nanocomposite (α-MnO2/HT-GCN) for highly efficient CIP degradation. The α-MnO2 nanoparticles (NPs) were prepared by a simple hydrothermal technique before being decorated on HT-GCN (H denotes protonation and T represents thermal-decomposition-graphitic carbon nitride). Tauc plots were used to calculate the band gap values of the photocatalysts α-MnO2 (1.74 eV), GCN (2.84 eV), HT-GCN (2.63 eV), and α-MnO2/HT-GCN (2.31 eV). The mechanism was investigated by various scavengers, particularly isopropanol (•OH) makes a significant role in the photodegradation process. The degradation percentage for ciprofloxacin was 89.2% and the rate of reaction R2 = 0.9913. This study demonstrates a unique method for developing a heterojunction-based nanocomposite of α-MnO2/HT-GCN, which exhibit better light absorption performance.

Functionalization and Haemolytic analysis of pure superparamagnetic magnetite nanoparticle for hyperthermia application.

Superparamagnetic iron oxide nanoparticles (SPIONPs) are widely used in clinical research. The single domain nanoparticles are used in magnetic fluid hyperthermia (MFH) to treat cancer. When nanoparticles are exposed to an external magnetic field, it generates heat destroying tumour cells. SPIONPs have a large surface area, so the particles tend to aggregate, which leads to the destabilization of the colloidal system. To enhance the stability and biocompatibility of the nanomaterials, it is necessary to coat the surface with biocompatible material. Magnetite (Fe3O4) is a superparamagnetic nanoparticle (SPNPs) that was functionalized with oleic acid (OA) by sol-gel process using ethanol as the solvent. The oleic acid-coated magnetite (OA-Fe3O4) was characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), UV-Visible diffuse reflectance spectroscopy (UV-DRS) and vibrating sample magnetometer (VSM). The haemolysis test has been used to investigate the haemocompatibility properties of nanomaterials. Hyperthermia study shows a high SAR value for the concentration of 1 mg/ml at the field of 600 Oe and frequency of 316 kHz. The OA coating enhanced the haemocompatibility of synthesized magnetite nanoparticles which can be used for magnetic fluid hyperthermia applications.

Highly Efficient Sulfur and Nitrogen Codoped Graphene Quantum Dots as a Metal-Free Green Photocatalyst for Photocatalysis and Fluorescent Ink Applications.

The demand for modern organic pollutant treatment has prompted the development of environmentally acceptable photocatalytic processes. In this work, we report novel nitrogen and sulfur codoped graphene quantum dot (S,N-GQD) based photocatalysts and fluorescent ink for the first time. For the degradation of organic dyes under visible irradiation, a hydrothermal technique was employed to generate S,N-GQD green nanomaterials. The synthesized samples were examined using XRD, HR-TEM, EDX, FT-IR, PL, and UV-vis spectroscopy. UV-DRS was used to determine the energy band gap of S,N-GQDs, and it was obtained to be around ∼2.54 eV. To explore the catalytic behavior of the produced S,N-GQDs as green nanomaterials, organic dyes (i.e., crystal violet and Alizarin yellow) have been used as a reference dye in this study. Using several radical scavenging agents, the photocatalytic mechanism was examined. This novel photocatalyst offers a promising alternative for the breakdown of organic pollutants. Moreover, these S,N-GQDs can also be used as fluorescent ink for imaging purposes and security reasons.

Novel Metal-Free Fluorescent Sensor Based on Molecularly Imprinted Polymer N-CDs@MIP for Highly Selective Detection of TNP.

In this article, we designed a fluorometric sensor based on nitrogen-passivated carbon dots infused with a molecularly imprinted polymer (N-CDs@MIP) via a reverse microemulsion technique using 3-aminopropyltriethoxysilane as a functional monomer, tetraethoxysilane as a cross-linker, and 2,4,6-trinitrophenol (TNP) as a template. The synthesized probe was used for selective and sensitive detection of trace amounts of TNP. The infusion of N-CDs (QY-21.6 percent) with a molecularly imprinted polymer can increase the fluorescent sensor sensitivity to detect TNP. Removal of template molecules leads to the formation of a molecularly imprinted layer, and N-CDs@MIP fluorescence response was quenched by TNP. The developed fluorescence probe shows a fine linear range from 0.5 to 2.5 nM with a detection limit of 0.15 nM. The synthesized fluorescent probe was used to analyze TNP in regular tap and lake water samples.

Green Synthesis of Self-Passivated Fluorescent Carbon Dots Derived from Rice Bran for Degradation of Methylene Blue and Fluorescent Ink Applications.

Recently, natural products are the powerful carbon source to synthesize carbon dots (CDs) with interesting physical and chemical properties. In this present work, we report a facile hydrothermal synthesis method for preparing fluorescent carbon dots using a biogenic precursor of rice bran without any surface passivation agent. The synthetic methodology was easy, simple, environmental friendly and convenient. Structural and optical properties of the RB-CDs have been studied by UV-visible, Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), Fluorescence spectra and X-ray photoelectron spectroscopy (XPS) techniques. The prepared RB-CDs exhibited green emission upon irradiation with UV light and the calculated fluorescence quantum yield (QY) was found to be 7.4%. The morphological features of the synthesized RB-CDs were characterized by High-Resolution Transmission Electron Microscopy (HR-TEM), the average size of the RB-CDs was found to be 2.96 nm. The synthesized RB-CDs were beneficially applied as a catalyst for the catalytic degradation of methylene blue (MB) dye using NaBH4 as the reducing agent in the ambient conditions. The degradation of MB dye under light illumination was 89.20% in 30 min. Further, the obtained highly fluorescent RB-CDs were efficiently utilized as a fluorescent ink for luminescent pattern printing (patterning agent) in the anti-counterfeiting applications.