Functionalization of Reduced Graphene Oxide with β-cyclodextrin Modified Palladium Nanoparticles for the Detection of Hydrazine in Environmental Water Samples

Lignosulfonate-Assisted In Situ Deposition of Palladium Nanoparticles on Carbon Nanotubes for the Electrocatalytic Sensing of Hydrazine

This paper presents a novel modified electrode for an amperometric hydrazine sensor based on multi-walled carbon nanotubes (MWCNTs) modified with lignosulfonate (LS) and decorated with palladium nanoparticles (NPds). The MWCNT/LS/NPd hybrid was characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The electrochemical properties of the electrode material were evaluated using cyclic voltammetry and chronoamperometry. The results showed that GC/MWCNT/LS/NPd possesses potent electrocatalytic properties towards the electro-oxidation of hydrazine. The electrode demonstrated exceptional electrocatalytic activity coupled with a considerable sensitivity of 0.166 μA μM-1 cm-2. The response was linear from 3.0 to 100 µM L-1 and 100 to 10,000 µM L-1, and the LOD was quantified to 0.80 µM L-1. The efficacy of the modified electrode as an electrochemical sensor was corroborated in a study of hydrazine determination in water samples.

Enhanced electrocatalytic activity of fluorine doped tin oxide (FTO) by trimetallic spinel ZnMnFeO4/CoMnFeO4 nanoparticles as a hydrazine electrochemical sensor

In the present study, ZnMnFeO₄ and CoMnFeO₄ tri-metallic spinel oxide nanoparticles (NPs) were provided using hydrothermal methods. The nanoparticles have been characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and electrochemical techniques. A reliable and reproducible electrochemical sensor based on ZnMnFeO₄/CoMnFeO₄/FTO was fabricated for rapid detection and highly sensitive determination of hydrazine by the DPV technique. It is observed that the modified electrode causes a sharp growth in the oxidation peak current and a decrease in the potential for oxidation, contrary to the bare electrode. The cyclic voltammetry technique showed that there is high electrocatalytic activity and excellent sensitivity in the suggested sensor for hydrazine oxidation. Under optimal experimental conditions, the DPV method was used for constructing the calibration curve, and a linear range of 1.23 × 10^-6 M to 1.8 × 10^-4 M with a limit of detection of 0.82 ± 0.09 μM was obtained. The obtained results indicate that ZnMnFeO₄/CoMnFeO₄/FTO nano sensors exhibit pleasant stability, reproducibility, and repeatability in hydrazine measurements. In addition, the suggested sensor was efficiently employed to ascertain the hydrazine in diverse samples of cigarette tobacco.

Application of nanomaterials decorated with cyclodextrins as sensing elements for environment analysis

Environmental pollution has brought adverse socio-economic consequences. Organic pollutants and heavy metals are the main culprits of environmental pollution. It is of great importance to develop novel, simple, rapid, sensitive, and low-cost detection approaches for sensing trace pollutants in environmental samples. A lot of detection strategies which are based on varieties of nanomaterials have been developed for environmental analysis in past decades. In this review, we retrospect a variety of nanomaterials decorated with cyclodextrins (CDs), including carbon nanomaterials decorated with CDs, noble metal nanomaterials decorated with CDs and other nanomaterials decorated with CDs, and their application in environmental analysis. CDs is a type of ideal modifying molecules which could recognize targets, improve the solubility and dispersibility of corresponding functionalized materials, and enhance the detecting performance of designed sensors. CDs have been widely immobilized to carbon nanomaterials, noble metal nanomaterials, phosphorene (BP) nanocomposites, metal organic framework (MOF), and magnetic nanomaterials, and these nanocomposites have been utilized as the sensing elements for different target analytes. Immobilizing CDs on different nanomaterials could extremely expand the development of new sensing systems for environmental analysis based on these materials, greatly broaden the species of sensing targets, and apparently improve their sensing performance. Herein, the nanomaterials decorated with CDs, as sensing elements for environmental analysis, were reviewed including the types of nanomaterials decorated with CDs and their applications in various sensing strategies for environmental analysis. Finally, the perspectives of the nanomaterials decorated with CDs used as sensing elements were also discussed.

da Silva Alves D, Okeke C, Breslin CB. Cyclodextrins as Supramolecular Recognition Systems: Applications in the Fabrication of Electrochemical Sensors

Supramolecular chemistry, although focused mainly on noncovalent intermolecular and intramolecular interactions, which are considerably weaker than covalent interactions, can be employed to fabricate sensors with a remarkable affinity for a target analyte. In this review the development of cyclodextrin-based electrochemical sensors is described and discussed. Following a short introduction to the general properties of cyclodextrins and their ability to form inclusion complexes, the cyclodextrin-based sensors are introduced. This includes the combination of cyclodextrins with reduced graphene oxide, carbon nanotubes, conducting polymers, enzymes and aptamers, and electropolymerized cyclodextrin films. The applications of these materials as chiral recognition agents and biosensors and in the electrochemical detection of environmental contaminants, biomolecules and amino acids, drugs and flavonoids are reviewed and compared. Based on the papers reviewed, it is clear that cyclodextrins are promising molecular recognition agents in the creation of electrochemical sensors, chiral sensors, and biosensors. Moreover, they have been combined with a host of materials to enhance the detection of the target analytes. Nevertheless, challenges remain, including the development of more robust methods for the integration of cyclodextrins into the sensing unit.

Rational Design of Novel Efficient Palladium Electrode Embellished 3D Hierarchical Graphene/Polyimide Foam for Hydrogen Peroxide Electroreduction

The electrocatalytic applications of traditional polyimide film and carbon nanomaterials are hindered due to a shortage of three-dimensional hierarchical conductivity and porous structure. Herein, a novel polyimide-based electrode based on a highly efficient palladium nanocatalyst embellished three-dimensional reduced graphene oxide/polyimide foam (Pd/3D RGO@PI foam, signed PRP) toward H₂O₂ electroreduction was designed and prepared through thermal foaming procedure, followed by facile dip-drying method and electrodeposition. As expected, such a binder-free, 3D hierarchical structure PRP electrode presented high catalytic property, good stability, as well as low activation energy toward H₂O₂ electroreduction during the electrochemical measurement period. The PRP electrode showed a reduction current density of 810 mA·cm^-2 at -0.2 V (vs Ag/AgCl) in 2.0 mol·L^-1 H₂SO₄ and 2.0 mol·L^-1 H₂O₂. Moreover, the PRP electrode also illustrated good reproducibility and repeatability. Reproducibility presented almost 95.8% of the initial current density after 1000 cycles test. Also, the activation energy of H₂O₂ electroreduction on 3D PRP electrode was 21.624 kJ·mol^-1. Benefiting from the 3D hierarchical structure and efficient catalyst, the PRP electrode exhibited excellent electrocatalytic performance and was considered to be a potential candidate material for fuel cells.

Ultrafine AuPd nanoparticles supported on amine functionalized monochlorotriazinyl β-cyclodextrin as highly active catalysts for hydrogen evolution from formic acid dehydrogenation

Au_0.3Pd_0.7/A-M-β-CD exhibits remarkable catalytic activity for hydrogen evolution from formic acid, which is attributed to strong metal–support interaction.

Recent developments in the synthesis and applications of graphene-family materials functionalized with cyclodextrins

The introduction of cyclodextrin species to graphene-family materials (GFMs) constitutes an important area of research, especially in terms of the development of applied nanoscience. The chemistry of cyclodextrins is the so-called host-guest chemistry, which has impacted on many fields of research, including catalysis, electrochemistry and nanomedicine. Cyclodextrins are water-soluble and biocompatible supramolecules, and therefore they may introduce new interesting properties to GFMs and may enhance the physicochemical/biological features of native GFMs. The reported methods for the conjugation of cyclodextrins to GFMs utilize either covalent or non-covalent approaches. The recent progress in the applications of GFMs functionalized with cyclodextrins, with the respect to the chemistry and features of these conjugates, is discussed. Special consideration is also given to the recent developments in (i) nanomedicine, (ii) electrochemistry, (iii) adsorption and (iv) catalysis. Examples of these materials are discussed in this work, together with the future outlook on the impact of GFM-cyclodextrin conjugates in the development of applied nanoscience.

Citrate-Capped Hybrid Au-TiO2 Nanomaterial for Facile and Enhanced Electrochemical Hydrazine Oxidation

Effective and facile electrochemical oxidation of chemical fuels is pivotal for fuel cell applications. Herein, we report the electrocatalytic oxidation of hydrazine on a citrate-capped Au-TiO₂-modified glassy carbon electrode, which follows two different oxidation paths. These two pathways of hydrazine oxidation are ascribed to occur on Au and the activated TiO₂ surface of the Au-TiO₂ hybrid electrocatalyst. This activation was achieved through molecular capping of the Au-TiO₂ surface by citrate, which leads to favorable hydrazine oxidation with a lower Tafel slope compared to that of the clean surface of the respective materials, that is, Au and TiO₂.