Molecules

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13 pages, 1076 KiB

Open AccessArticle

Fabrication of Membrane Sensitive Electrodes for the Validated Electrochemical Quantification of Anti-Osteoporotic Drug Residues in Pharmaceutical Industrial Wastewater

by Sherif A. Abdel-Gawad, Obaid Afzal, Hany H. Arab, Alhumaidi B. Alabbas and Abdulmalik M. Alqarni

Molecules 2021, 26(16), 5093; https://doi.org/10.3390/molecules26165093 - 22 Aug 2021

Cited by 2 | Viewed by 2281

Abstract

Accurate and precise application of ion-selective electrodes (ISEs) in the quantification of environmental pollutants is a strenuous task. In this work, the electrochemical response of alendronate sodium trihydrate (ALN) was evaluated by the fabrication of two sensitive and delicate membrane electrodes, viz. polyvinyl [...] Read more.

Accurate and precise application of ion-selective electrodes (ISEs) in the quantification of environmental pollutants is a strenuous task. In this work, the electrochemical response of alendronate sodium trihydrate (ALN) was evaluated by the fabrication of two sensitive and delicate membrane electrodes, viz. polyvinyl chloride (PVC) and glassy carbon (GC) electrodes. A linear response was obtained at concentrations from 1 × 10⁻⁵ to 1 × 10⁻² M for both electrodes. A Nernstian slope of 29 mV/decade over a pH range of 8–11 for the PVC and GC membrane electrodes was obtained. All assay settings were carefully adjusted to obtain the best electrochemical response. The proposed technique was effectively applied for the quantification of ALN in pure form and wastewater samples, acquired from manufacturing industries. The proposed electrodes were effectively used for the determination of ALN in real wastewater samples without any prior treatment. The current findings guarantee the applicability of the fabricated ISEs for the environmental monitoring of ALN. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Invited Papers in the Electrochemistry Section)

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9 pages, 2703 KiB

Open AccessArticle

Spectroelectrochemical Behavior of Polycrystalline Gold Electrode Modified by Reverse Micelles

by Miriam C. Rodríguez González, Maximina Luis-Sunga, Ricardo M. Souto, Alberto Hernández Creus, Elena Pastor and Gonzalo García

Molecules 2021, 26(2), 471; https://doi.org/10.3390/molecules26020471 - 18 Jan 2021

Cited by 1 | Viewed by 2760

Abstract

The increasing demand for raising the reliability of electronic contacts has led to the development of methods that protect metal surfaces against atmospheric corrosion agents. This severe problem implies an important economic cost annually but small amounts of corrosion inhibitors can control, decrease [...] Read more.

The increasing demand for raising the reliability of electronic contacts has led to the development of methods that protect metal surfaces against atmospheric corrosion agents. This severe problem implies an important economic cost annually but small amounts of corrosion inhibitors can control, decrease or avoid reactions between a metal and its environment. In this regard, surfactant inhibitors have displayed many advantages such as low price, easy fabrication, low toxicity and high inhibition efficiency. For this reason, in this article, the spectroelectrochemical behavior of polycrystalline gold electrode modified by reverse micelles (water/polyethyleneglycol-dodecylether (BRIJ 30)/n-heptane) is investigated by atomic force microscopy (AFM), potentiodynamic methods and electrochemical impedance spectroscopy (EIS). Main results indicate a strong adsorption of a monolayer of micelles on the gold substrate in which electron tunneling conduction is still possible. Therefore, this method of increasing the corrosion resistance of gold contacts is usable only in conditions of long-term storage but not in the operation of devices with such contacts. In this regard, the micelle coating must be removed from the surface of the gold contacts before use. Finally, the aim of the present work is to understand the reactions occurring at the surfactant/metal interface, which may help to improve the fabrication of novel electrodes. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Invited Papers in the Electrochemistry Section)

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16 pages, 5019 KiB

Open AccessArticle

Scaling up Studies on PEMFC Using a Modified Serpentine Flow Field Incorporating Porous Sponge Inserts to Observe Water Molecules

by Muthukumar Marappan, Rengarajan Narayanan, Karthikeyan Manoharan, Magesh Kannan Vijayakrishnan, Karthikeyan Palaniswamy, Smagul Karazhanov and Senthilarasu Sundaram

Molecules 2021, 26(2), 286; https://doi.org/10.3390/molecules26020286 - 8 Jan 2021

Cited by 11 | Viewed by 2859

Abstract

Flooding of the cathode flow channel is a major hindrance in achieving maximum performance from Proton Exchange Membrane Fuel Cells (PEMFC) during the scaling up process. Water accumulated between the interface region of Gas Diffusion Layer (GDL) and rib of the cathode flow [...] Read more.

Flooding of the cathode flow channel is a major hindrance in achieving maximum performance from Proton Exchange Membrane Fuel Cells (PEMFC) during the scaling up process. Water accumulated between the interface region of Gas Diffusion Layer (GDL) and rib of the cathode flow field can be removed by the use of Porous Sponge Inserts (PSI) on the ribs. In the present work, the experimental investigations are carried out on PEMFC for the various reaction areas, namely 25, 50 and 100 cm². Stoichiometry value of 2 is maintained for all experiments to avoid variations in power density obtained due to differences in fuel utilization. The experiments include two flow fields, namely Serpentine Flow Field (SFF) and Modified Serpentine with Staggered provisions of 4 mm PSI (4 mm × 2 mm × 2 mm) Flow Field (MSSFF). The peak power densities obtained on MSSFF are 0.420 W/cm², 0.298 W/cm² and 0.232 W/cm² compared to SFF which yields 0.242 W/cm², 0.213 W/cm² and 0.171 W/cm² for reaction areas of 25, 50 and 100 cm² respectively. Further, the reliability of experimental results is verified for SFF and MSSFF on 25 cm² PEMFC by using Electrochemical Impedance Spectroscopy (EIS). The use of 4 mm PSI is found to improve the performance of PEMFC through the better water management. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Invited Papers in the Electrochemistry Section)

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17 pages, 5167 KiB

Open AccessArticle

Recycling Chocolate Aluminum Wrapping Foil as to Create Electrochemical Metal Strip Electrodes

by Hairul Hisham Hamzah, Nur Hidayah Saleh, Bhavik Anil Patel, Mohd Muzamir Mahat, Saiful Arifin Shafiee and Turgut Sönmez

Molecules 2021, 26(1), 21; https://doi.org/10.3390/molecules26010021 - 23 Dec 2020

Cited by 7 | Viewed by 5215

Abstract

The development of low-cost electrode devices from conductive materials has recently attracted considerable attention as a sustainable means to replace the existing commercially available electrodes. In this study, two different electrode surfaces (surfaces 1 and 2, denoted as S1 and S2) were fabricated [...] Read more.

The development of low-cost electrode devices from conductive materials has recently attracted considerable attention as a sustainable means to replace the existing commercially available electrodes. In this study, two different electrode surfaces (surfaces 1 and 2, denoted as S1 and S2) were fabricated from chocolate wrapping aluminum foils. Energy dispersive X-Ray (EDX) and field emission scanning electron microscopy (FESEM) were used to investigate the elemental composition and surface morphology of the prepared electrodes. Meanwhile, cyclic voltammetry (CV), chronoamperometry, electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) were used to assess the electrical conductivities and the electrochemical activities of the prepared electrodes. It was found that the fabricated electrode strips, particularly the S1 electrode, showed good electrochemical responses and conductivity properties in phosphate buffer (PB) solutions. Interestingly, both of the electrodes can respond to the ruthenium hexamine (Ruhex) redox species. The fundamental results presented from this study indicate that this electrode material can be an inexpensive alternative for the electrode substrate. Overall, our findings indicate that electrodes made from chocolate wrapping materials have promise as electrochemical sensors and can be utilized in various applications. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Invited Papers in the Electrochemistry Section)

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12 pages, 3962 KiB

Open AccessArticle

Electrografting of 4-Carboxybenzenediazonium on Glassy Carbon Electrode: The Effect of Concentration on the Formation of Mono and Multilayers

by Sereilakhena Phal, Kenichi Shimizu, Daniel Mwanza, Philani Mashazi, Andrey Shchukarev and Solomon Tesfalidet

Molecules 2020, 25(19), 4575; https://doi.org/10.3390/molecules25194575 - 7 Oct 2020

Cited by 18 | Viewed by 4409

Abstract

Grafting of electrodes with diazonium salts using cyclic voltammetry (CV) is a well-established procedure for surface modification. However, little is known about the effect of the concentration of the diazonium salt on the number of layers grafted on the electrode surface. In this [...] Read more.

Grafting of electrodes with diazonium salts using cyclic voltammetry (CV) is a well-established procedure for surface modification. However, little is known about the effect of the concentration of the diazonium salt on the number of layers grafted on the electrode surface. In this work, the impact of concentration on the grafting of 4-carboxybenzenediazonium (4-CBD) onto a glassy carbon electrode (GCE) is elucidated. The number of layers grafted on the GCE was linearly dependent on the concentration of 4-CBD and varied between 0.9 and 4.3 when the concentration was varied between 0.050 and 0.30 mmol/L at 0.10 V.s⁻¹. Characterization of modified glassy carbon surface with X-ray photoelectron spectroscopy (XPS) confirmed the grafting of carboxyphenyl layer on the surface. Grafting with 0.15 mmol/L 4-CBD (1 CV cycle) did not form a detectable amount of carboxyphenyl (CP) moieties at the surface, while a single scan with higher concentration (2.5 mmol/L) or multiple scans (22 cycles) gave detectable signals, indicating formation of multilayers. We also demonstrate the possibility of removing the thin layer grafted on a glassy carbon electrode by applying high oxidation potential +1.40 V. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Invited Papers in the Electrochemistry Section)

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13 pages, 10113 KiB

Open AccessArticle

Surface Oxidation of Nano-Silicon as a Method for Cycle Life Enhancement of Li-ion Active Materials

by Maciej Ratynski, Bartosz Hamankiewicz, Dominika A. Buchberger and Andrzej Czerwinski

Molecules 2020, 25(18), 4093; https://doi.org/10.3390/molecules25184093 - 7 Sep 2020

Cited by 7 | Viewed by 3756

Abstract

Among the many studied Li-ion active materials, silicon presents the highest specific capacity, however it suffers from a great volume change during lithiation. In this work, we present two methods for the chemical modification of silicon nanoparticles. Both methods change the materials’ electrochemical [...] Read more.

Among the many studied Li-ion active materials, silicon presents the highest specific capacity, however it suffers from a great volume change during lithiation. In this work, we present two methods for the chemical modification of silicon nanoparticles. Both methods change the materials’ electrochemical characteristics. The combined XPS and SEM results show that the properties of the generated silicon oxide layer depend on the modification procedure employed. Electrochemical characterization reveals that the formed oxide layers show different susceptibility to electro-reduction during the first lithiation. The single step oxidation procedure resulted in a thin and very stable oxide that acts as an artificial SEI layer during electrode operation. The removal of the native oxide prior to further reactions resulted in a very thick oxide layer formation. The created oxide layers (both thin and thick) greatly suppress the effect of silicon volume changes, which significantly reduces electrode degradation during cycling. Both modification techniques are relatively straightforward and scalable to an industrial level. The proposed modified materials reveal great applicability prospects in next generation Li-ion batteries due to their high specific capacity and remarkable cycling stability. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Invited Papers in the Electrochemistry Section)

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11 pages, 5022 KiB

Open AccessArticle

Electrospinning Ag-TiO₂ Nanorod-Loaded Air Treatment Filters and Their Applications in Air Purification

by Shan-Jiang Wang, Xiao-Yang Zhang, Dan Su, Yun-Fan Wang, Chun-Meng Qian, Xin-Ru Zhou, Yi-Zhi Li and Tong Zhang

Molecules 2020, 25(15), 3369; https://doi.org/10.3390/molecules25153369 - 24 Jul 2020

Cited by 11 | Viewed by 3167

Abstract

The efficient treatment of the problem of air pollution is a practical issue related to human health. The development of multi-functional air treatment filters, which can remove various kinds of pollutants, including particulate matter (PM) and organic gases, is a tireless pursuit aiming [...] Read more.

The efficient treatment of the problem of air pollution is a practical issue related to human health. The development of multi-functional air treatment filters, which can remove various kinds of pollutants, including particulate matter (PM) and organic gases, is a tireless pursuit aiming to address the actual needs of humans. Advanced materials and nano-manufacturing technology have brought about the opportunity to change conventional air filters for practical demands, with the aim of achieving the high-efficiency utilization of photons, a strong catalytic ability, and the synergetic degradation of multi-pollutants. In this work, visible-responding photocatalytic air treatment filters were prepared and combined with a fast and cost-effective electrospinning process. Firstly, we synthesized Ag-loaded TiO₂ nanorod composites with a controlled size and number of loaded Ag nanoparticles. Then, multi-functional air treatment filters were designed by loading catalysts on electrospinning nanofibers combined with a programmable brush. We found that such Ag-TiO₂ nanorod composite-loaded nanofibers displayed prominent PM filtration (~90%) and the degradation of organic pollutants (above 90%). The superior performance of purification could be demonstrated in two aspects. One was the improvement of the adsorption of pollutants derived from the increase of the specific surface area after the loading of catalysts, and the other was the plasmonic hot carriers, which induced a broadening of the optical absorption in the visible light range, meaning that many more photons were utilized effectively. The designed air treatment filters with synergistic effects for eliminating both PM and organic pollutants have promising potential for the future design and application of novel air treatment devices. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Invited Papers in the Electrochemistry Section)

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19 pages, 3094 KiB

Open AccessArticle

Study on FcγRn Electrochemical Receptor Sensor and Its Kinetics

by Dandan Peng, Dingqiang Lu and Guangchang Pang

Molecules 2020, 25(14), 3206; https://doi.org/10.3390/molecules25143206 - 14 Jul 2020

Cited by 3 | Viewed by 2279

Abstract

Neonatal γ-immunoglobulin (IgG) Fc receptor (FcγRn) is a receptor that transports IgG across the intestinal mucosa, placenta, and mammary gland, ensuring the balance of IgG and albumin in the body. These functions of FcγRn depend on the intracellular signal transduction and activation caused [...] Read more.

Neonatal γ-immunoglobulin (IgG) Fc receptor (FcγRn) is a receptor that transports IgG across the intestinal mucosa, placenta, and mammary gland, ensuring the balance of IgG and albumin in the body. These functions of FcγRn depend on the intracellular signal transduction and activation caused by the combination of its extracellular domain and IgG Fc domain. Nevertheless, there are still no kinetic studies on this interaction. Consequently, in the present study, we successfully constructed the human FcγRn (hFcγRn) electrochemical receptor sensor. The signal amplification system formed by chitosan nanogold-hFcγRn protein and horseradish peroxidase was used to simulate the cell signal amplification system in vivo, and the kinetic effects between seven IgG and hFcγRn receptors from different species were quantitatively measured. The results showed that the interaction of these seven IgGs with hFcγRn was similar to the catalytic kinetics of enzyme and substrate, and there was a ligand-receptor saturation effect. The order of the interconnect allosteric constants (K_a), which is similar to the Michaelis constant (K_m), was human IgG < bovine IgG < horse IgG < rabbit IgG < sheep IgG < donkey IgG < quail IgY. The results showed that hFcγRn had the strongest ability to transport human IgG, which was consistent with the evolution of the system. Therefore, our hFcγRn electrochemical receptor sensor can be used to measure and evaluate the interconnected allosteric network. It is also an essential parameter of the interaction between hFcγRn and different IgGs and, thus, provides a new detection and evaluation method for immunoemulsion, therapeutic monoclonal antibody therapy, heteroantibody treatment, and half-life research. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Invited Papers in the Electrochemistry Section)

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