Publications

Due to environmental problems by the use of synthetic fibers in composite materials, researchers are more concerned with searching for eco-friendly materials. Consequently, the use of reinforcing fibers of natural origin is the best option that promotes the obtaining of materials that do not harm the environment. This paper presents characterization of Cortaderia selloana grass (Pampas) fibers by physical-chemical analysis, FTIR, XRD, thermogravimetric analysis, single fiber tensile test and SEM analysis. Diameter (372.6 µm), density (1261 kg/m3), cellulose content (53.7 wt.%), crystallinity index (22%), tensile strength (20 ± 1.0 MPa), Young’s modulus (8.88 GPa), and thermal stability (320°C) properties were identified in the Cortaderia selloana grass (Pampas) fibers. Overall properties of these fibers showed that it could be an alternative source as reinforcement material for the manufacture of composite materials.

This study introduced a simple method developed for enantioselective extraction of D-phenylalanine prior to its determination by high performance liquid chromatography. The method was based on silica gel developed by surface immobilized new chiral ionic liquid (SG-L-PhAlaC2NTf2). Surface characteristics of the synthesized SG-L-PhAlaC2NTf2 phase were confirmed by both FT-IR spectroscopy and scanning electron microscope. Results of the selectivity study and effect of pH on SG-L-PhAlaC2NTf2 phase showed that SG-L-PhAlaC2NTf2 was the most enantioselective toward D- phenylalanine. Data of adsorption isotherm study revealed that the adsorption capacity of SG-L- PhAlaC2NTf2 for D-phenylalanine was the most by 97.35% as compared to activated silica gel at pH value of 3.0 and after one hour contact time. Results demonstrated that the adsorption of D- phenylalanine onto SG-L-PhAlaC2NTf2 phase well followed with Langmuir adsorption isotherm and pseudo second-order kinetic models. The efficiency of the methodology was ultimately validated by implementing it to real water samples with satisfactory results.

Polyaniline-silver (PANI-Ag)/ferritin (Frt)/glucose oxidase (GOx) biocompatible anode was utilized for creating power from glucose. The synthesized nanocomposite was investigated by EIS (Electrochemical impedance spectroscopy), XRD (X-ray diffraction), FTIR (Fourier transform infrared spectroscopy), SEM (Scanning electron microscopy), CV (Cyclic voltammetry), and LSV (Linear sweep voltammetry) to know the morphology, crystallinity and electrochemical behaviour of the nanocomposite. The electroactive support (PANI-Ag) was utilized for the immobilization of the enzyme (GOx) and a biocompatible mediator (Frt) to enhance the electrical signals. The electrochemical estimations of the manufactured bioanode were done by utilizing cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The current density obtained by the PANI-Ag/Frt/GOx bioanode was observed to be 25.40 ± 2 mA cm^-2 at 40 mM of glucose concentration at a scan rate of 100 mVs^-1.

Mesoporous thin films with various compositions are unique architectures for photoelectrochemical (PEC) solar cells. In this paper, we report the synthesis of highly ordered, multi-layered, continuous mesoporous TiO2 thin films with uniform large pores, crystalline walls and tunable film thickness, via a ligand-assisted evaporation induced self assembly (EISA) method. A Ti(acetylacetone) precursor and a diblock copolymer PEO-b-PS are employed for the controlled assembly of the TiO2/template mesostructure, followed by a two-step pyrolysis that generates carbon residue as an intermediate protection layer to support the TiO2 framework and mesostructures during the crystallization. Other transition metal ion dopants (such as Cr, Ni and Co) can be facilely incorporated into the TiO2 frameworks by co-assembly of these metal acetylacetone precursors during the EISA process. The obtained TiO2 thin film possesses an ordered monoclinic mesostructure distorted from a (110)-oriented primitive cubic structure, uniform and tunable large pores of 10–30 nm, a large surface area of ∼100 m2 g−1 and a high crystallinity anatase wall. The film thickness can be well controlled from 150 nm to several microns to tune the absorption, with the capability of generating free-standing film morphologies. Furthermore, this designed architecture allows for effective post-deposition of other small-bandgap semiconductor nanomaterials inside the large, open and interconnecting mesopores, leading to significantly improved solar absorption and photoconversion. As a proof-of-concept, we demonstrate that the photoanodes made of 4.75 μm thick mesoporous TiO2 film with deposited cadmium sulfide quantum dots exhibit excellent performance in PEC water splitting, with an optimized photocurrent density of 6.03 mA cm−2 and a photoconversion efficiency of 3.9%. These multi-layered mesoporous TiO2-based thin films can serve as a unique architecture for PEC and other solar energy conversion and utilization.

Stranded on a nanoparticle: For the first time, zeolitic imidazolate framework-8 nanoparticles (ZIFNPs) have been used in an effective fluorescent sensing platform for nucleic acids. The DNA detection is accomplished in two steps: 1) ZIFNPs adsorb and quench the dye-labeled single-stranded DNA probe, and 2) subsequent hybridization of the probe with its target produces double-stranded DNA, which detaches from the ZIFNP. The present system shows a high selectivity down to single-base mismatch (see figure).

Abstract Searching for inexpensive hydrogen evolution reaction (HER) electrocatalysts with high activity has attracted considerable research interest in the past years. Reported herein is the topotactic fabrication of self‐supported Cu 3 P nanowire arrays on commercial porous copper foam (Cu 3 P NW/CF) from its Cu(OH) 2 NW/CF precursor by a low‐temperature phosphidation reaction. Remarkably, as an integrated three‐dimensional hydrogen‐evolving cathode operating in acidic electrolytes, Cu 3 P NW/CF maintains its activity for at least 25 hours and exhibits an onset overpotential of 62 mV, a Tafel slope of 67 mV dec −1 , and a Faradaic efficiency close to 100 %. Catalytic current density can approach 10 mA cm −2 at an overpotential of 143 mV.

Abstract In this study, we prepared a novel series of diester‐functionalized cationic gemini surfactants (C m ‐E2O2‐C m ) containing ethylene oxide as a spacer with varying alkyl chain lengths and characterized by 1 H NMR, FT‐IR, elemental analysis, and ESI‐MS. The physicochemical properties of the geminis were explored by tensiometry, fluorescence, dye solubilization, and Krafft point. These geminis acquire superior surface activity than the conventional surfactants. Fluorescence spectroscopy analysis affirmed that the micropolarity and aggregation number of micelles diminished with increase in the alkyl chain length. These geminis represent a new group of amphiphiles of considerably high biodegradability, better cleavability, and low toxicity as assessed by BOD test, FT‐IR analysis, and HC 50 analysis, respectively. They also showed significant level of antimicrobial activity toward some specified bacterial strains of Gram‐positive and Gram‐negative by using agar well diffusion method. Furthermore, the thermogravimetric analysis provided information regarding thermal stabilities of the newly synthesized gemini surfactants.

Cellulose is the main component of natural fibers whose content varies greatly depending on the type of plant and its treatment. Therefore, it is necessary to examine the effect of chemical treatment on natural fiber properties. This study successfully extracted the content from Pandan duri (Pandanus tectorius) fiber through alkalization, bleaching, and acid hydrolysis. The effect of these chemical treatments on the characteristics of fiber surface, shape, chemical composition, crystallinity, and thermal properties was examined and analyzed. Subsequently, the cellulose components in the structure and the removal of lignin groups were characterized by Fourier transform infrared (FTIR) spectroscopy spectrum analysis. The surface morphology analysis was done by scanning electron microscopy (SEM) that showed the raw fiber surface was still in the structure of bundles. However, it was decomposed into cellulose fibrils after chemical treatment with a diameter of about 2 µm – 20 µm. The chemical composition for cellulose content increased by 90.5%, while hemicellulose decreased by 89.6% after acid hydrolysis treatment. Also, X-ray (XRD) analysis showed crystallinity increased from 39.5% for raw fibers to 67.7% after the hydrolysis. Thermal gravimetric analysis (TGA) showed higher degradation temperature of micro cellulose offered better thermal stability compared to raw fibers. In conclusion, the cellulose from Pandanus tectorius fiber can be used to reinforce biocomposites as an alternative to synthetic fibers for sustainability of environment.