Publications

Nitrite, widely found in the environment and the food industry, poses a great threat to human health because of its potential toxicity, and its detection is highly important. We report that a MoN nanosheet array on carbon cloth (MoN NA/CC) behaves as an efficient catalyst for nitrite reduction in neutral solution. As a nitrite sensor, this MoN NA/CC offers a wide linear range from 1 μM to 5 mM and a low detection limit of 3 nM (S/N = 3), with a high sensitivity of 4319 μA mM^-1 cm^-2 and long-term stability and reproducibility.

Ni nanoparticles (≈ 8 nm) have been prepared at about 15 wt% loading strongly grafted on N-doped graphitic carbon matrix [[email protected](N)C] by pyrolysis of Ni(OAc)2 adsorbed on chitosan. [email protected](N)C was used as catalyst for H2 storage/release on N-ethylcarbazole (EC). [email protected](N)C exhibits higher H2 storage capacity than analogous Ni nanoparticles (NPs) supported on silica. The addition of minute amounts (18 ppm) of Pt increases significantly the H2 storage/release activity of [email protected](N)C due to effect of Pt promoting H spill over the Ni NPs. There is no linear correlation between Pt concentration and hydrogenation/dehydrogenation activity of [email protected](N)C, the lowest Pt loading (18 ppm) resulting in the most efficient Pt/[email protected](N)C for hydrogenation-dehydrogenation of EC. This fact was attributed to the presence of small Pt clusters or single atoms, while higher concentration would correspond to a less-efficient larger cluster regime. The most efficient Pt/[email protected](N)C-18 catalyst was used for four consecutive hydrogenation/dehydrogenation cycles, exhibiting some fatigue in the H2 storage/release of the same EC batch that was attributed to the increase in the product mixture complexity upon cycling, with the formation of some intermediates that undergo more difficult hydrogenation/dehydrogenation reaction as well as partial catalyst deactivation. After four cycles, (Pt)[email protected](N)C exhibits in the fifth use a H2 storage capacity of 5.2 wt%, somewhat lower than the 5.8 wt% H2 capacity of the fresh sample, while no changes in the XRD, TEM and XPS characterization of the five-times used catalyst compared to the fresh material is observed.

Global climate change is already affecting the environment, as glaciers are receding, ice on rivers and lakes is melting, plant and animal range`s have altering, and trees are blooming early. Therefore, focus has shifted towards sustainable materials. There is a growing desire for materials that have a unique combination of qualities that metals, polymers, and other materials cannot provide, therefore scientists are turning their focus to green composites. Green composites offer a wide range of uses in automotive, aerospace, and marine applications. Composites are multiphase resources with separate interfaces that contain chemically different materials. Composites are made up of a variety of materials that are distinct in nature, and they give a set of desirable features that are superior to those of their predecessors or parents. Natural fibers are less expensive, more readily available, rust-resistant, plentiful, nontoxic, and safe for human skin, eyes, and respiratory systems. Green composites are created by combining renewable fibers with polymers (matrix) to create a new class of composites known as "green composites." This review includes studies on various animal-based fibers and their applications. In this article, recent advancements in the field of these fibers and their composites of fibers are also discussed. The physical, chemical, and mechanical properties are also discussed in this paper. Moreover, the benefits and drawbacks of using these fibers are also discussed in detail. Finally, the paper gives an outline of the topic. The results from composites constructed from each fiber are provided, along with appropriate references for more in-depth analysis studies. This review is specially performed to strengthen the knowledge bank of the young researchers working in the field of natural composites.

There is an urgent demand to develop earth-abundant electrocatalysts for efficient and durable water oxidation under mild conditions. A nickel-substituted cobalt-borate nanowire array is developed on carbon cloth (Ni-Co-Bi/CC) via oxidative polarization of NiCo₂ S₄ nanoarray in potassium borate (K-Bi). As a bimetallic electrocatalyst for water oxidation, such Ni-Co-Bi/CC is superior in catalytic activity and durability in 0.1 m K-Bi (pH: 9.2), with a turnover frequency of 0.33 mol O₂ s^-1 at the overpotential of 500 mV and nearly 100% Faradaic efficiency. To drive a geometrical catalytic current density of 10 mA cm^-2 , it only needs overpotential of 388 mV, 34 mV less than that for Co-Bi/CC, outperforming reported non-noble-metal catalysts operating under benign conditions. Notably, its activity is maintained over 80 000 s. Density functional theory calculations suggest that the O* to OOH* conversion is the rate-determining step and Ni substitution decreases the free energy on Co-Bi from 2.092 to 1.986 eV.

A novel phenothiazine derivative conjugated with vinylcyclohexenyl-malononitrile (PTZ-CDN) was synthesized through the Knoevenagel reaction of 10-octyl-10H-phenothiazine-3,7-dicarbaldehyde with 2-(3,5,5-trimethylcyclohex-2-en-1-ylidene)-malononitrile and fully characterized. The UV-vis absorption spectra of PTZ-CDN in different solvents showed a λ_max band at 497-531 nm with a high molar extinction coefficient attributed to intramolecular charge transfer (ICT) with the characteristics of a π-π* transition. Increasing the solvent polarity resulted in a bathochromic shift of λ_max . The PTZ-CDN fluorescence emission spectra were more sensitive to increasing the solvent polarity than the absorption spectra; they displayed a blue shift of λ_em by 85 nm. To understand the behaviour of the PTZ-CDN derivative, Stokes' shift ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>Δ</mml:mi> <mml:mover><mml:mi>ν</mml:mi> <mml:mo>¯</mml:mo></mml:mover> <mml:mo>)</mml:mo></mml:math> with respect to the solvent polarity, Lippert-Mataga and linear solvation-energy relationship (LSER) models were applied in which the LSER showed better regression than the Lippert-Mataga plots (r² = 0.9627). Finally, the TD-density functional theory (DFT) electronic transition spectra in dioxane and dimethyl formamide (DMF) were calculated. The DFT data showed that λ_max resulted from the support of the highest occupied molecular orbital to the lowest unoccupied molecular orbital transition with 74% and 99% in dioxane and DMF, respectively.