Activated porous carbon supported rhenium composites as electrode materials for electrocatalytic and supercapacitor applications

New analytical strategies amplified with carbon-based nanomaterial for sensing food pollutants

The most significant topic currently under the moonlight is Nanobiotechnology and engineered nanomaterials. The novel characteristics displayed by engineered Nanomaterials, especially carbon-based nanomaterials, have spurred interest in its potential application in the food industry. It has provided opportunities for finding solutions to the long-standing challenges in the food industry to assess food safety, maintain food quality, extend the shelf life of produce, and efficiently deliver nutrients. Nanomaterials can be incorporated in food sensors facilitating efficient monitoring of crop maturity and detecting biological and chemical contaminants. When integrated into food packages, nanomaterials could aid in assessing the freshness and improving the quality of packaged foods. In addition, more efficient delivery of nutrients could be possible in foods fortified using nano compounds. The initial section of this review gives an overview of the broad application of nanotechnology in the food industry and carbon-based nanomaterials. The latter part focuses on nanotechnology in biosensors for food safety and quality monitoring.

Rhenium Sulfide Incorporated in Molybdenum Sulfide Nanosheets for High-Performance Symmetric Supercapacitors with Enhanced Capacitance

Supercapacitors are considered potential energy storage devices and have drawn significant attention due to their superior intrinsic advantages. Herein, we report the synthesis of ReS₂ embedded in MoS₂ nanosheets (RMS-31) by a hydrothermal technique. The prepared RMS-31 electrode material demonstrated superior pseudocapacitive behavior in 1 M KOH electrolyte solution, which is confirmed by the heterostructure of RMS-31 nanosheet architectures. RMS-31 has a specific capacitance of 244 F g^-1 at a current density of 1 A g^-1 and a greater areal capacitance of 540 mF cm^-2 at a current density of 5 mA cm^-2. The symmetric supercapacitor device with the RMS-31 electrode delivers an energy density of 28 W h cm^-2 with a power density of 1 W cm^-2 and reveals long-term stability at a constant current density of 5 mA cm^-2 for 10,000 cycles while accomplishing a retention of 66.5%. The high performance of this symmetric device is attributed to the synergistic effect of ReS₂ and MoS₂ and the presence of the metallic 1T-MoS₂ phase in the RMS-31 electrode. To the best of our knowledge, this is the first report of increasing the interlayer spacing of 2H-MoS₂ by incorporating ReS₂ for symmetric supercapacitor applications.

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.

Rational design of ultrahigh sensitive sunset yellow sensor based on 3D hierarchical porous graphitic carbon with sub-nanopores

The content of sunset yellow (SY) in food must be strictly controlled, because its excessive intake may cause many adverse health effects. Herein, we proposed an ultrasensitive SY sensor by using hierarchical porous graphitic (HPG) carbon derived from polyaniline hydrogel. After a first step of polymerization, the HPG carbon was prepared through carbonization and further chemical activation. In particular, the activation process endowed the HPG carbon with a high content of optimized porous architecture (sub-nanoporous surface area accounts for more than 90% of microporous surface area), and thus providing a structural basis for high efficiency of SY pre-concentration on HPG carbon surface. Therefore, the proposed sensor showed record-high sensitivity (5285.7 A M^-1 cm^-2) and ultra-low detection limit (0.15 nM), which represents a performance improvement in SY sensing. Furthermore, the sensor displays excellent selectivity, reproducibility and stability, exhibiting a great perspective in ultrasensitive monitoring of SY in commercial products.

Disposable Electrochemical Sensor for Food Colorants Detection by Reduced Graphene Oxide and Methionine Film Modified Screen Printed Carbon Electrode

A facile synthesis of reduced graphene oxide (rGO) and methionine film modified screen printed carbon electrode (rGO-methionine/SPCE) was proposed as a disposable sensor for determination of food colorants including amaranth, tartrazine, sunset yellow, and carminic acid. The fabrication process can be achieved in only 2 steps including drop-casting of rGO and electropolymerization of poly(L-methionine) film on SPCE. Surface morphology of modified electrode was studied by scanning electron microscopy (SEM). This work showed a successfully developed novel disposable sensor for detection of all 4 dyes as food colorants. The electrochemical behavior of all 4 food colorants were investigated on modified electrodes. The rGO-methionine/SPCE significantly enhanced catalytic activity of all 4 dyes. The pH value and accumulation time were optimized to obtain optimal condition of each colorant. Differential pulse voltammetry (DPV) was used for determination, and two linear detection ranges were observed for each dye. Linear detection ranges were found from 1 to 10 and 10 to 100 µM for amaranth, 1 to 10 and 10 to 85 µM for tartrazine, 1 to 10 and 10 to 50 µM for sunset yellow, and 1 to 20 and 20 to 60 µM for carminic acid. The limit of detection (LOD) was calculated at 57, 41, 48, and 36 nM for amaranth, tartrazine, sunset yellow, and carminic acid, respectively. In addition, the modified sensor also demonstrated high tolerance to interference substances, good repeatability, and high performance for real sample analysis.

Fabrication of Co3O4 nanoparticle-decorated porous activated carbon electrode for the electrochemical detection of 4-nitrophenol

Preparation of Co3O4@BVFC for the electrochemical detection of 4-NP.

Electrodeposition process of perrhenate ions from KNO3 and Na2SO4 background electrolytes in the presence of citric acid

Processes involved in the electrodeposition of perrhenate ions were studied from two different potassium nitrate and sodium sulfate background electrolytes in the presence of citric acid on graphite electrode by cyclic voltammetry method. Anodic and cathodic potentials of deposited film were determined. After electrolysis process, morphology and content of obtained deposited layers were investigated by SEM and X-Ray methods. The coated film from sodium sulfate background electrolyte was not uniform and Re content was 60.83-65.5%, in case of potassium nitrate electrolyte, the deposited film was more densely located, and Re content was 80.94-82.52%. In the presence of nickel sulfate and citric acid, an alloy was formed with content of Re 80.94-82.52%, 14.10-11.83% of Ni, 4.96-5.66% of impurities, which were confirmed by X-Ray method. The current density decreased with addition of citric acid into sodium sulfate background electrolyte and in cathodic area, the reduction potential of perrhenate ions remained the same, but oxidation potentials changed from 0.25 to 0.35 V and from 0.5 to 0.6 V. The influence of citric acid on potentials of the processes of reduction and oxidation of perrhenate ions from potassium nitrate gave following results: reduction peaks shifted from -0.35 to -0.55 V, and multi peaks of oxidation appeared which were not noticeable without citric acid. It was shown that citric acid has inhibitory effect on reduction and oxidation of perrhenate ions. It is shown that the electrochemical reduction of perrhenate ions leads to the formation of rhenium dioxide in different forms.

Simple Preparation of Porous Carbon-Supported Ruthenium: Propitious Catalytic Activity in the Reduction of Ferrocyanate(III) and a Cationic Dye

The present study involves the synthesis, characterization, and catalytic application of ruthenium nanoparticles (Ru NPs) supported on plastic-derived carbons (PDCs) synthesized from plastic wastes (soft drink bottles) as an alternative carbon source. PDCs have been further activated with CO₂ and characterized by various analytical techniques. The catalytic activity of Ru@PDC for the reduction of potassium hexacyanoferrate(III), (K₃[Fe(CN)₆]), and new fuchsin (NF) dye by NaBH₄ was performed under mild conditions. The PDCs had spherical morphology with an average size of 0.5 μm, and the Ru NP (5 ± 0.2 nm) loading (4.01 wt %) into the PDC provided high catalytic performance for catalytic reduction of ferrocyanate(III) and NF dye. This catalyst can be recycled more than six times with only a minor loss of its catalytic activity. In addition, the stability and reusability of the Ru@PDC catalyst are also discussed.