Electrocatalytic oxidation of hydrazine at glassy carbon electrode modified with ethylenediamine cellulose immobilized palladium nanoparticles

A CTAB-assisted PANI-MoS2 nanosheet flower morphology for the highly sensitive electrochemical detection of hydrazine

In this work, cetyl trimethylammonium bromide (CTAB)-assisted polyaniline-molybdenum disulfide (CPANI-MoS2) nanosheets with a flower morphology have been synthesized through in situ polymerization and a hydrothermal method. The composite was analyzed for structural modification through X-ray diffraction (XRD) to examine chemical changes and the presence of functional groups via Fourier transform infrared (FTIR) and Raman spectroscopy techniques. The surface morphology was identified by field-emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HR-TEM) techniques. The CPANI-MoS2 nanosheet glassy carbon electrode (GCE) offers a novel strategy for the electrochemical detection of carcinogenic hydrazine. The cyclic voltammetry (CV) curve demonstrated a quasi-reversible behaviour with a high-surface area. Furthermore, differential pulse voltammetry (DPV) analysis of hydrazine detection showed a wide linear range from 10 μM to 100 μM, a low limit of detection of 0.40 μM, and a high sensitivity of 7.23 μA μM cm-2. The determination of hydrazine in a water sample and the recovery percentage were found to be 100.31% and 103.73%, respectively. The CPANI-MoS2 nanosheet GCE significantly contributed to the high electroanalytical oxidation activity due to the CTAB surfactant modifying the flower-like nanosheet morphology, which enables the easy adsorption of hydrazine analyte species and exhibits a high current rate with a rapid detection response.

Wood-Sourced Polymers as Support for Catalysis by Group 10 Transition Metals

Despite providing interesting solutions to reduce the number of synthetic steps, to decrease energy consumption or to generate less waste, therefore contributing to a more sustainable way of producing important chemicals, the expansion of the use of homogeneous catalysis in industrial processes is hampered by several drawbacks. One of the most important is the difficulty to recycle the noble metals generating potential high costs and pollution of the synthesized products by metal traces detrimental to their applications. Supporting the metals on abundant and cheap biosourced polymers has recently appeared as an almost ideal solution: They are much easier to recover from the reaction medium and usually maintain high catalytic activity. The present bibliographical review focuses on the development of catalysts based on group 10 transition metals (nickel, palladium, platinum) supported on biopolymers obtained from wood, such as cellulose, hemicellulose, lignin, and their derivatives. The applications of these catalysts in organic synthesis or depollution are also addressed in this review with examples of C-C couplings, oxidation, or hydrogenation reactions.

Electrochemical Detection of Hydrazine by Carbon Paste Electrode Modified with Ferrocene Derivatives, Ionic Liquid, and CoS2-Carbon Nanotube Nanocomposite

The electrocatalytic performance of carbon paste electrode (CPE) modified with ferrocene-derivative (ethyl2-(4-ferrocenyl[1,2,3]triazol-1-yl)acetate), ionic liquid (n-hexyl-3-methylimidazolium hexafluorophosphate), and CoS2-carbon nanotube nanocomposite (EFTA/IL/CoS2-CNT/CPE) was investigated for the electrocatalytic detection of hydrazine. CoS2-CNT nanocomposite was characterized by field emission scanning electron microscopy, X-ray powder diffraction, and transmission electron microscopy. According to the results of cyclic voltammetry, the EFTA/IL/CoS2-CNT-integrated CPE has been accompanied by greater catalytic activities for hydrazine oxidation compared to the other electrodes in phosphate buffer solution at a pH 7.0 as a result of the synergistic impact of fused ferrocene-derivative, IL, and nanocomposite. The sensor responded linearly with increasing concentration of hydrazine from 0.03 to 500.0 μM with a higher sensitivity (0.073 μA μM-1) and lower limit of detection (LOD, 0.015 μM). Furthermore, reasonable reproducibility, lengthy stability, and excellent selectivity were also attained for the proposed sensor. Finally, EFTA/IL/CoS2-CNT/CPE was applied for the detection of hydrazine in water samples, and good recoveries varied from 96.7 to 103.0%.

A glassy carbon electrode modified with a nanocomposite prepared from Pd/Al layered double hydroxide and carboxymethyl cellulose for voltammetric sensing of hydrogen peroxide

A Pd/Al layered double hydroxide/carboxymethyl cellulose nanocomposite (CMC@Pd/Al-LDH) was fabricated using carboxymethyl cellulose as a green substrate via co-precipitation method. The synthesized nanocomposite was characterized using different methods such as scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray powder diffraction, transmission electron microscopy, and electrochemical techniques. A glassy carbon electrode (GCE) was then modified with the suspended composite to obtain an electrochemical sensor for hydrogen peroxide (H₂O₂). The voltammetric (cathodic) current of the modified GCE was measured at -380 mV (vs. Ag/AgCl), at the scan rate of 50 mV.s^-1. Results show a linear dynamic range of 1 to 120 μM, and a 0.3 µM limit of detection (at S/N = 3). Intraday and interday relative standard deviations are in the ranges of 4.9-5.4% and 6.8-7.3%, respectively. The sensor was applied for the determination of H₂O₂ in basil extracts, milk, and spiked river water samples. The recoveries are between 96.60 and 102.30%. Graphical abstractA Pd/Al layered double hydroxide/carboxymethyl cellulose nanocomposite (CMC@Pd/Al-LDH) was fabricated via co-precipitation method and was characterized using scanning electron microscopy, Energy-dispersive X-ray spectroscopy, X-ray powder diffraction, transmission electron microscopy and electrochemical techniques. CMC@Pd/Al-LDH was used to fabricate H₂O₂ electrochemical sensor.

CoPtx/γ-Al2O3 bimetallic nanoalloys as promising catalysts for hydrazine electrooxidation

Stable bimetallic catalysts composed of CoPtx/γ-Al2O3 (x = Pt/Co molar ratio) were synthesized by wet impregnation method followed by calcination and the H2 reduction. The powders were characterized using XRD, AAS, BET, SEM, EDX, TPR, and TPO techniques. The prepared catalysts were drop casted on the glassy carbon electrode (GCE) and catalytic performance was examined for hydrazine electrooxidation in alkaline medium via cyclic voltammetry (CV). All the compositions in CoPtx/γ-Al2O3 series showed high responses towards hydrazine electrooxidation, however; high activity of CoPt0.034/γ-Al2O3 catalyst inferred it as a best material with an anodic peak current (iP) response of 200 μA at 0.86 V. The prominent electrochemical (EC) responses for this composition are attributed to better accessible surface area resulting in a fast electron transfer. The CoPtx/γ-Al2O3 catalysts are reported as the robust and superior prospective materials for extensive electroanalytical and catalytic studies.

Square planar Ni(ii) complexes of acetoneN4-phenyl-thiosemicarbazone andin situgenerated benzoyl thiosemicarbazide ligands: synthesis, spectral and structural characterizations, thermal behaviour and electrochemical studies

Two novel complexes [Ni(Hapt)₂] (1) and [Ni(btsc)] (2) have been synthesized from Hapt and Hbtsc by the reaction of Ni(ii) salt.

Copper iodide nanoparticles supported on magnetic aminomethylpyridine functionalized cellulose: a new heterogeneous and recyclable nanomagnetic catalyst for facile access to N-sulfonylamidines under solvent free conditions

A highly active catalyst based on CuI nanoparticles supported on magnetic aminomethylpyridine functionalized cellulose has been synthesized. It well catalyzes the multicomponent synthesis of N-sulfonylamidines under solvent free conditions.

Low loaded palladium nanoparticles on ethylenediamine-functionalized cellulose as an efficient catalyst for electrochemical hydrogen production

In this study, for the first time, a carbon paste electrode was modified with palladium nanoparticles supported on ethylenediamine-functionalized cellulose, and its performance for electrocatalytic hydrogen production was examined.

Cobalt phthalocyanine modified electrodes utilised in electroanalysis: nano-structured modified electrodes vs. bulk modified screen-printed electrodes

Cobalt phthalocyanine (CoPC) compounds have been reported to provide electrocatalytic performances towards a substantial number of analytes. In these configurations, electrodes are typically constructed via drop casting the CoPC onto a supporting electrode substrate, while in other cases the CoPC complex is incorporated within the ink of a screen-printed sensor, providing a one-shot economical and disposable electrode configuration. In this paper we critically compare CoPC modified electrodes prepared by drop casting CoPC nanoparticles (nano-CoPC) onto a range of carbon based electrode substrates with that of CoPC bulk modified screen-printed electrodes in the sensing of the model analytes l-ascorbic acid, oxygen and hydrazine. It is found that no “electrocatalysis” is observed towards l-ascorbic acid using either of these CoPC modified electrode configurations and that the bare underlying carbon electrode is the origin of the obtained voltammetric signal, which gives rise to useful electroanalytical signatures, providing new insights into literature reports where “electrocatalysis” has been reported with no clear control experiments undertaken. On the other hand true electrocatalysis is observed towards hydrazine, where no such voltammetric features are witnessed on the bare underlying electrode substrate.

Multi-walled carbon nanotubes decorated with palladium nanoparticles as a novel platform for electrocatalytic sensing applications

Sensitive detection of glucose using a glassy carbon electrode modified with glucose oxidase and multi-walled carbon nanotubes decorated with palladium nanoparticles.