Research

Jump to: Review

17 pages, 22698 KiB

Open AccessFeature PaperArticle

Tuning the Electrochemical Properties of Novel Asymmetric Integral Sulfonated Polysulfone Cation Exchange Membranes

by Ahmet Halil Avci, Cédric Van Goethem, Timon Rijnaarts, Sergio Santoro, Marco Aquino, Gianluca Di Profio, Ivo F. J. Vankelecom, Wiebe M. De Vos, Enrica Fontananova and Efrem Curcio

Molecules 2021, 26(2), 265; https://doi.org/10.3390/molecules26020265 - 07 Jan 2021

Cited by 6 | Viewed by 2711

Abstract

In this study, novel asymmetric integral cation exchange membranes were prepared by the wet phase inversion of sulfonated polysulfone (SPSf) solutions. SPSf with different degrees of sulfonation (DS) was synthesized by variation in the amount of chlorosulfonic acid utilized as a sulfonating agent. [...] Read more.

In this study, novel asymmetric integral cation exchange membranes were prepared by the wet phase inversion of sulfonated polysulfone (SPSf) solutions. SPSf with different degrees of sulfonation (DS) was synthesized by variation in the amount of chlorosulfonic acid utilized as a sulfonating agent. The characterization of SPSf samples was performed using FTIR and ¹H-NMR techniques. SPSf with a DS of 0.31 (0.67 meq/g corresponding ion exchange capacity) was chosen to prepare the membranes, as polymers with a higher DS resulted in poor mechanical properties and excessive swelling in water. By a systematic study, the opportunity to tune the properties of SPSf membranes by acting on the composition of the polymeric solution was demonstrated. The effect of two different phase inversion parameters, solvent type and co-solvent ratio, were investigated by morphological and electrochemical characterization. The best properties (permselectivity of 0.86 and electrical resistance of 6.3 Ω∙cm²) were obtained for the membrane prepared with 2-propanol (IPA):1-Methyl-2-pyrrolidinone (NMP) in a 20:80 ratio. This membrane was further characterized in different solution concentrations to estimate its performance in a Reverse Electrodialysis (RED) operation. Although the estimated generated power was less than that of the commercial CMX (Neosepta) membrane, used as a benchmark, the tailor-made membrane can be considered as a cost-effective alternative, as one of the main limitations to the commercialization of RED is the high membrane price. Full article

(This article belongs to the Special Issue Exclusive Papers of the Editorial Board Members (EBMs) of the Electrochemistry Section of Molecules)

► Show Figures

Figure 1

15 pages, 4362 KiB

Open AccessFeature PaperArticle

CoMnO₂-Decorated Polyimide-Based Carbon Fiber Electrodes for Wire-Type Asymmetric Supercapacitor Applications

by Young-Hun Cho, Jae-Gyoung Seong, Jae-Hyun Noh, Da-Young Kim, Yong-Sik Chung, Tae Hoon Ko and Byoung-Suhk Kim

Molecules 2020, 25(24), 5863; https://doi.org/10.3390/molecules25245863 - 11 Dec 2020

Cited by 11 | Viewed by 2543

Abstract

In this work, we report the carbon fiber-based wire-type asymmetric supercapacitors (ASCs). The highly conductive carbon fibers were prepared by the carbonized and graphitized process using the polyimide (PI) as a carbon fiber precursor. To assemble the ASC device, the CoMnO₂-coated [...] Read more.

In this work, we report the carbon fiber-based wire-type asymmetric supercapacitors (ASCs). The highly conductive carbon fibers were prepared by the carbonized and graphitized process using the polyimide (PI) as a carbon fiber precursor. To assemble the ASC device, the CoMnO₂-coated and Fe₂O₃-coated carbon fibers were used as the cathode and the anode materials, respectively. Herein, the nanostructured CoMnO₂ were directly deposited onto carbon fibers by a chemical oxidation route without high temperature treatment in presence of ammonium persulfate (APS) as an oxidizing agent. FE-SEM analysis confirmed that the CoMnO₂-coated carbon fiber electrode exhibited the porous hierarchical interconnected nanosheet structures, depending on the added amount of APS, and Fe₂O₃-coated carbon fiber electrode showed a uniform distribution of porous Fe₂O₃ nanorods over the surface of carbon fibers. The electrochemical properties of the CoMnO₂-coated carbon fiber with the concentration of 6 mmol APS presented the enhanced electrochemical activity, probably due to its porous morphologies and good conductivity. Further, to reduce the interfacial contact resistance as well as improve the adhesion between transition metal nanostructures and carbon fibers, the carbon fibers were pre-coated with the Ni layer as a seed layer using an electrochemical deposition method. The fabricated ASC device delivered a specific capacitance of 221 F g⁻¹ at 0.7 A g⁻¹ and good rate capability of 34.8% at 4.9 A g⁻¹. Moreover, the wire-type device displayed the superior energy density of 60.2 Wh kg⁻¹ at a power density of 490 W kg⁻¹ and excellent capacitance retention of 95% up to 3000 charge/discharge cycles. Full article

(This article belongs to the Special Issue Exclusive Papers of the Editorial Board Members (EBMs) of the Electrochemistry Section of Molecules)

► Show Figures

Figure 1

13 pages, 4705 KiB

Open AccessArticle

Effect of Reducing Agent on Solution Synthesis of Li₃V₂(PO₄)₃ Cathode Material for Lithium Ion Batteries

by Ali Yaghtin, Seyyed Morteza Masoudpanah, Masood Hasheminiasari, Amirhossein Salehi, Dorsasadat Safanama, Chong Kim Ong, Stefan Adams and Mogalahalli V. Reddy

Molecules 2020, 25(16), 3746; https://doi.org/10.3390/molecules25163746 - 17 Aug 2020

Cited by 11 | Viewed by 3942

Abstract

In this study, Li₃V₂(PO₄)₃ (LVP) powders are prepared by a solution synthesis method. The effects of two reducing agents on crystal structure and morphology and electrochemical properties are investigated. Preliminary studies on reducing agents such as [...] Read more.

In this study, Li₃V₂(PO₄)₃ (LVP) powders are prepared by a solution synthesis method. The effects of two reducing agents on crystal structure and morphology and electrochemical properties are investigated. Preliminary studies on reducing agents such as oxalic acid and citric acid, are used to reduce the vanadium (V) precursor. The oxalic acid-assisted synthesis induces smaller particles (30 nm) compared with the citric acid-assisted synthesis (70 nm). The LVP powders obtained by the oxalic acid exhibit a higher specific capacity (124 mAh g⁻¹ at 1C) and better cycling performance (122 mAh g⁻¹ following 50 cycles at 1C rate) than those for the citric acid. This is due to their higher electronic conductivity caused by carbon coating and downsizing the particles. The charge-discharge plateaus obtained from cyclic voltammetry are in good agreement with galvanostatic cycling profiles. Full article

(This article belongs to the Special Issue Exclusive Papers of the Editorial Board Members (EBMs) of the Electrochemistry Section of Molecules)

► Show Figures

Figure 1

9 pages, 1729 KiB

Open AccessFeature PaperArticle

Stabilization of the Highly Hydrophobic Membrane Protein, Cytochrome bd Oxidase, on Metallic Surfaces for Direct Electrochemical Studies

by Anton Nikolaev, Iryna Makarchuk, Alexander Thesseling, Jo Hoeser, Thorsten Friedrich, Frédéric Melin and Petra Hellwig

Molecules 2020, 25(14), 3240; https://doi.org/10.3390/molecules25143240 - 16 Jul 2020

Cited by 6 | Viewed by 2356

Abstract

The cytochrome bd oxidase catalyzes the reduction of oxygen to water in bacteria and it is thus an interesting target for electrocatalytic studies and biosensor applications. The bd oxidase is completely embedded in the phospholipid membrane. In this study, the variation of the [...] Read more.

The cytochrome bd oxidase catalyzes the reduction of oxygen to water in bacteria and it is thus an interesting target for electrocatalytic studies and biosensor applications. The bd oxidase is completely embedded in the phospholipid membrane. In this study, the variation of the surface charge of thiol-modified gold nanoparticles, the length of the thiols and the other crucial parameters including optimal phospholipid content and type, have been performed, giving insight into the role of these factors for the optimal interaction and direct electron transfer of an integral membrane protein. Importantly, all three tested factors, the lipid type, the electrode surface charge and the thiol length mutually influenced the stability of films of the cytochrome bd oxidase. The best electrocatalytic responses were obtained on the neutral gold surface when the negatively charged phosphatidylglycerol (PG) was used and on the charged gold surface when the zwitterionic phosphatidylethanolamine (PE) was used. The advantages of the covalent binding of the membrane protein to the electrode surface over the non-covalent binding are also discussed. Full article

(This article belongs to the Special Issue Exclusive Papers of the Editorial Board Members (EBMs) of the Electrochemistry Section of Molecules)

► Show Figures

Graphical abstract

15 pages, 3736 KiB

Open AccessArticle

Improving Photoelectrochemical Properties of Anodic WO₃ Layers by Optimizing Electrosynthesis Conditions

by Marta Zych, Karolina Syrek, Leszek Zaraska and Grzegorz D. Sulka

Molecules 2020, 25(12), 2916; https://doi.org/10.3390/molecules25122916 - 25 Jun 2020

Cited by 23 | Viewed by 3571

Abstract

Although anodic tungsten oxide has attracted increasing attention in recent years, there is still a lack of detailed studies on the photoelectrochemical (PEC) properties of such kind of materials grown in different electrolytes under various sets of conditions. In addition, the morphology of [...] Read more.

Although anodic tungsten oxide has attracted increasing attention in recent years, there is still a lack of detailed studies on the photoelectrochemical (PEC) properties of such kind of materials grown in different electrolytes under various sets of conditions. In addition, the morphology of photoanode is not a single factor responsible for its PEC performance. Therefore, the attempt was to correlate different anodizing conditions (especially electrolyte composition) with the surface morphology, oxide thickness, semiconducting, and photoelectrochemical properties of anodized oxide layers. As expected, the surface morphology of WO₃ depends strongly on anodizing conditions. Annealing of as-synthesized tungsten oxide layers at 500 °C for 2 h leads to obtaining a monoclinic WO₃ phase in all cases. From the Mott-Schottky analysis, it has been confirmed that all as prepared anodic oxide samples are n-type semiconductors. Band gap energy values estimated from incident photon−to−current efficiency (IPCE) measurements neither differ significantly for as−synthesized WO₃ layers nor depend on anodizing conditions such as electrolyte composition, time and applied potential. Although the estimated band gaps are similar, photoelectrochemical properties are different because of many different reasons, including the layer morphology (homogeneity, porosity, pore size, active surface area), oxide layer thickness, and semiconducting properties of the material, which depend on the electrolyte composition used for anodization. Full article

(This article belongs to the Special Issue Exclusive Papers of the Editorial Board Members (EBMs) of the Electrochemistry Section of Molecules)

► Show Figures

Graphical abstract

Review

Jump to: Research

12 pages, 4574 KiB

Open AccessReview

Electrochemical Reduction of Carbon Dioxide on Graphene-Based Catalysts

by Stefan Delgado, María del Carmen Arévalo, Elena Pastor and Gonzalo García

Molecules 2021, 26(3), 572; https://doi.org/10.3390/molecules26030572 - 22 Jan 2021

Cited by 9 | Viewed by 3748

Abstract

The current environmental situation requires taking actions regarding processes for energy production, thus promoting renewable energies, which must be complemented with the development of routes to reduce pollution, such as the capture and storage of CO₂. Graphene materials have been chosen [...] Read more.

The current environmental situation requires taking actions regarding processes for energy production, thus promoting renewable energies, which must be complemented with the development of routes to reduce pollution, such as the capture and storage of CO₂. Graphene materials have been chosen for their unique properties to be used either as electrocatalyst or as catalyst support (mainly for non-noble metals) that develop adequate efficiencies for this reaction. This review focuses on comparing experimental and theoretical results of the electrochemical reduction reaction of carbon dioxide (ECO₂RR) described in the scientific literature to establish a correlation between them. This work aims to establish the state of the art on the electrochemical reduction of carbon dioxide on graphene-based catalysts. Full article

(This article belongs to the Special Issue Exclusive Papers of the Editorial Board Members (EBMs) of the Electrochemistry Section of Molecules)

► Show Figures

Figure 1

27 pages, 9541 KiB

Open AccessReview

Application of Ionic Liquids in Electrochemistry—Recent Advances

by Gonçalo A. O. Tiago, Inês A. S. Matias, Ana P. C. Ribeiro and Luísa M. D. R. S. Martins

Molecules 2020, 25(24), 5812; https://doi.org/10.3390/molecules25245812 - 09 Dec 2020

Cited by 83 | Viewed by 8546

Abstract

In this review, the roles of room temperature ionic liquids (RTILs) and RTIL based solvent systems as proposed alternatives for conventional organic electrolyte solutions are described. Ionic liquids are introduced as well as the relevant properties for their use in electrochemistry (reduction of [...] Read more.

In this review, the roles of room temperature ionic liquids (RTILs) and RTIL based solvent systems as proposed alternatives for conventional organic electrolyte solutions are described. Ionic liquids are introduced as well as the relevant properties for their use in electrochemistry (reduction of ohmic losses), such as diffusive molecular motion and ionic conductivity. We have restricted ourselves to provide a survey on the latest, most representative developments and progress made in the use of ionic liquids as electrolytes, in particular achieved by the cyclic voltammetry technique. Thus, the present review comprises literature from 2015 onward covering the different aspects of RTILs, from the knowledge of these media to the use of their properties for electrochemical processes. Out of the scope of this review are heat transfer applications, medical or biological applications, and multiphasic reactions. Full article

(This article belongs to the Special Issue Exclusive Papers of the Editorial Board Members (EBMs) of the Electrochemistry Section of Molecules)

► Show Figures

Graphical abstract

13 pages, 3025 KiB

Open AccessReview

Towards High Performance Chemical Vapour Deposition V₂O₅ Cathodes for Batteries Employing Aqueous Media

by Dimitra Vernardou, Charalampos Drosos, Andreas Kafizas, Martyn E. Pemble and Emmanouel Koudoumas

Molecules 2020, 25(23), 5558; https://doi.org/10.3390/molecules25235558 - 26 Nov 2020

Cited by 10 | Viewed by 2023

Abstract

The need for clean and efficient energy storage has become the center of attention due to the eminent global energy crisis and growing ecological concerns. A key component in this effort is the ultra-high performance battery, which will play a major role in [...] Read more.

The need for clean and efficient energy storage has become the center of attention due to the eminent global energy crisis and growing ecological concerns. A key component in this effort is the ultra-high performance battery, which will play a major role in the energy industry. To meet the demands in portable electronic devices, electric vehicles, and large-scale energy storage systems, it is necessary to prepare advanced batteries with high safety, fast charge ratios, and discharge capabilities at a low cost. Cathode materials play a significant role in determining the performance of batteries. Among the possible electrode materials is vanadium pentoxide, which will be discussed in this review, due to its low cost and high theoretical capacity. Additionally, aqueous electrolytes, which are environmentally safe, provide an alternative approach compared to organic media for safe, cost-effective, and scalable energy storage. In this review, we will reveal the industrial potential of competitive methods to grow cathodes with excellent stability and enhanced electrochemical performance in aqueous media and lay the foundation for the large-scale production of electrode materials. Full article

(This article belongs to the Special Issue Exclusive Papers of the Editorial Board Members (EBMs) of the Electrochemistry Section of Molecules)

► Show Figures

Figure 1

67 pages, 4615 KiB

Open AccessReview

Carbon Anode in Carbon History

by César A. C. Sequeira

Molecules 2020, 25(21), 4996; https://doi.org/10.3390/molecules25214996 - 28 Oct 2020

Cited by 5 | Viewed by 4238

Abstract

This study examines how the several major industries, associated with a carbon artifact production, essentially belong to one, closely knit family. The common parents are the geological fossils called petroleum and coal. The study also reviews the major developments in carbon nanotechnology and [...] Read more.

This study examines how the several major industries, associated with a carbon artifact production, essentially belong to one, closely knit family. The common parents are the geological fossils called petroleum and coal. The study also reviews the major developments in carbon nanotechnology and electrocatalysis over the last 30 years or so. In this context, the development of various carbon materials with size, dopants, shape, and structure designed to achieve high catalytic electroactivity is reported, and among them recent carbon electrodes with many important features are presented together with their relevant applications in chemical technology, neurochemical monitoring, electrode kinetics, direct carbon fuel cells, lithium ion batteries, electrochemical capacitors, and supercapattery. Full article

(This article belongs to the Special Issue Exclusive Papers of the Editorial Board Members (EBMs) of the Electrochemistry Section of Molecules)

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

Exclusive Papers of the Editorial Board Members (EBMs) of the Electrochemistry Section of Molecules

Share This Special Issue

Special Issue Editor

Special Issue Information

Published Papers (9 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI