Graphene oxide@Ce-doped TiO2 nanoparticles as electrocatalyst materials for voltammetric detection of hazardous methyl parathion.

A sensitive voltammetric sensor has been developed for hazardous methyl parathion detection (MP) using graphene oxide@Ce-doped TiO2 nanoparticle (GO@Ce-doped TiO2 NP) electrocatalyst. The GO@Ce-doped TiO2 NPs were prepared through the sol-gel method and characterized by various physicochemical and electrochemical techniques. The GO@Ce-doped TiO2 NP-modified glassy carbon electrode (GCE) addresses excellent electrocatalytic activity towards MP detection for environmental safety and protection. The developed strategy of GO@Ce-doped TiO2 NPs at GCE surfaces for MP detection achieved excellent sensitivity (2.359 µA µM-1 cm-2) and a low detection limit (LOD) 0.0016 µM with a wide linear range (0.002 to 48.327 µM). Moreover, the fabricated sensor shows high selectivity and long-term stability towards MP detection; this significant electrode further paves the way for real-time monitoring of environmental quantitative samples with satisfying recoveries.

Selective Electrochemical Sensing Platform Based on the Synergy between Carbon Black and Single-Crystalline Bismuth Sulfide for Rapid Analysis of Antipyretic Drugs.

Nanomaterials are of significant interest in acetaminophen (APAP) detection in pharmaceutical samples. Herein, a carbon black/single-crystalline rodlike bismuth sulfide (CB/Bi2S3) composite prepared by an ultrasonic method is reported and utilized for the rapid analysis of APAP. The highly oriented edge reactive sites of the CB/Bi2S3 composite promoted synergy and good electrochemical sensing performance with a fast electron transfer rate and low overpotential (0.35 V). Therefore, a CB/Bi2S3 composite-modified glassy carbon electrode (GCE) was applied to the selective determination of APAP by the voltammetric technique. The CB/Bi2S3 composite-modified electrode showed the lowest limit of detection of APAP (1.9 nM) with excellent sensitivity. The proposed CB/Bi2S3/GCE platform exhibited high selectivity, excellent stability (87.15%), and reproducibility. Also, the CB/Bi2S3/GCE sensor was then successfully used to analyze an APAP pharmaceutical sample and exhibited satisfactory outcomes. Therefore, the CB/Bi2S3-modified GCE sensor platform would be a low-cost and robust GCE electrode material for APAP detection.

Electrochemical determination of caffeic acid in antioxidant beverages samples via a facile synthesis of carbon/iron-based active electrocatalyst.

An electrochemical method has described for the voltammetric determination and oxidation of caffeic acid (CA) at a glassy carbon electrode (GCE) modified carbon/iron-based active catalyst as a sensing platform. In this study, we have developed a highly sensitive electrochemical CA sensor with f-MWCNTs/α-NaFeO2 composite, which was developed by a simple ultrasonication method. The microstructural features of the f-MWCNTs/α-NaFeO2 composite characterized by different physicochemical and analytical techniques. Under the optimized condition, the developed sensor archive the ultra-sensitivity (44.6859 µA µM-1cm-2) at a lower concentration with excellent linearity (R2 = 0.9943) and which shows low detection limit (LOD = 0.002 µM) and Limit of quantification (LOQ = 0.0068 µM) by using differential pulse voltammetry (DPV) technique. The suggested sensor may improve the effective and efficient platform to the determination of CA in the healthcare system.

A La3+-doped TiO2 nanoparticle decorated functionalized-MWCNT catalyst: novel electrochemical non-enzymatic sensing of paraoxon-ethyl.

The development of novel chemical sensors for pesticide detection has found particular application in the area of environmental monitoring. However, designing primary sensors as weapons to destroy contaminants (e.g., paraoxon-ethyl) in water and soil remains a challenge. Herein, we show different strategies, such as modification of TiO2 NPs through La3+ doping and decoration of f-MWCNTs, which can provide possibilities for notable developments in electrocatalytic performance. Using this approach, we introduce an active La3+ doped TiO2 NP decorated f-MWCNT electrocatalyst for pollutant monitoring applications. Thereby, our findings move towards an outstanding LOD (0.0019 µM) performance, high selectivity, and exceptional sensitivity (7.6690 µA µM-1 cm-2) on an as-presented catalytic platform for a PE sensor. Interestingly, the practical applicability of the suggested catalyst shows a rich sensing platform for PE-contaminated environmental samples.

A chitosan grafted mesoporous carbon aerogel for ultra-sensitive voltammetric determination of isoniazid.

A screen-printed carbon electrode (SPCE) was modified with chitosan (Chit) supported on carbon aerogel (CA) to obtain an electrochemical sensor for the tuberculosis drug isoniazid (INZ). The interconnected mesoporous structure of Chit/CA provides a large surface area (SBET = 461 m2 g-1) and good porosity (VTot = 0.69 cm3 g-1). Besides, the modified SPCE displayed enhanced electrocatalytic activity due to the presence of numerous active sites (such as >C=O, -NH-, -NH2, -OH). Figures of merit include (a) a typical working voltage of 0.28 V (vs. Ag/AgCl), (b) high sensitivity (8.09 µA µM-1 cm-2), (c) a wide linear response to INZ (0.01-115 µM) and (d) a low detection limit (8 nM). The modified electrode has successfully been applied to the determination of INZ in spiked serum and urine, and recoveries ranged from 97.8 to 99.8%. Graphical abstract Schematic illustration of preparation and applications of a nanocomposite consisting of chitosan (Chit; CS) supported on carbon aerogel (CA) for electrochemical detection of isoniazid.

Gd2Te3: an antiferromagnetic semimetal.

We report high-precision magnetization ([Formula: see text]), magnetic susceptibility ([Formula: see text]), specific heat (C p (T, H)) and 'zero-field' electrical resistivity, [Formula: see text], data taken on Gd2Te3 single crystal over wide ranges of temperature and magnetic field (H), with either [Formula: see text]-axis or [Formula: see text]-plane. [Formula: see text] and [Formula: see text] unambiguously establish that the b-axis is the easy direction of magnetization whereas any direction in the ac-plane is a hard direction. The [Formula: see text]-type anomaly in 'zero-field' specific heat, C p (T, H = 0), and an abrupt drop in [Formula: see text] (characteristic of the paramagnetic (PM) - antiferromagnetic (AFM) phase transition) are observed at the Néel temperature, [Formula: see text] K. [Formula: see text] and C p (T,H) clearly demonstrate that [Formula: see text] shifts to lower temperatures with increasing H irrespective of whether H points in the easy or hard direction. When [Formula: see text], the [Formula: see text] isotherms at temperatures in the range 2.5 K [Formula: see text] [Formula: see text] K reveal the existence of a field-induced spin-flop (SF) transition at fields 4.0 T [Formula: see text] [Formula: see text] [Formula: see text] 4.5 T. The first principles electronic band structure and density of states calculations, based on the density functional theory, correctly predict an AFM ground state (stabilized primarily by the 4f  Gd3+ - 5p  Te2-- 4f  Gd3+ superexchange interactions) and the observed semi-metallic behavior for the Gd2Te3 compound. Moreover, these calculations yield the values [Formula: see text] [Formula: see text] for the ordered magnetic moment per Gd atom at T = 0, [Formula: see text] mJ mol-1 K-2 for the Sommerfeld coefficient for the electronic specific heat contribution and [Formula: see text] K for the Curie-Weiss temperature, respectively. These theoretical estimates conform well with the corresponding experimental values [Formula: see text] [Formula: see text], [Formula: see text] mJ mol-1 K-2 and [Formula: see text] K.

Carbon supported olivine type phosphate framework: a promising electrocatalyst for sensitive detection of dopamine.

In this study, a layered olivine-type LiMnPO4/functionalized-multiwall carbon nanotube (f-MWCNTs) composite is used as an electrochemically active material for the real-time detection of dopamine. A wet-chemical ultrasonication process is used to combine LiMnPO4 with f-MWCNTs at room temperature. The composite was subjected to various structural, morphological and electrochemical studies. The blending of olivine-type LiMnPO4 into the f-MWCNTs is revealed by TEM analysis. The electrochemical activities of the LiMnPO4/f-MWCNTs composite are systematically investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) for the real-time detection of dopamine. Furthermore, the applicability of the as prepared LiMnPO4/f-MWCNTs composite was extended for the detection of human serum (E48) and rat brain-serum (C7) samples with satisfactory recoveries for the real-time applications. All these studies revealed that the layered olivine-type LiMnPO4/f-MWCNTs composite is a potential candidate in the field of electrochemical sensing.