Materials

Research

Jump to: Review

15 pages, 4643 KiB

Open AccessArticle

Composites Based on Electrodeposited WO₃ and TiO₂ Nanoparticles for Photoelectrochemical Water Splitting

by Ramunas Levinas, Elizabeth Podlaha, Natalia Tsyntsaru and Henrikas Cesiulis

Materials 2024, 17(19), 4914; https://doi.org/10.3390/ma17194914 - 8 Oct 2024

Viewed by 742

Abstract

Photoelectrochemically active WO₃ films were fabricated by electrodeposition from an acidic (pH 2), hydrogen-peroxide-containing electrolyte at −0.5 V vs. SCE. WO₃-TiO₂ composites were then synthesized under the same conditions, but with 0.2 g/L of anatase TiO₂ nanoparticles (⌀ [...] Read more.

Photoelectrochemically active WO₃ films were fabricated by electrodeposition from an acidic (pH 2), hydrogen-peroxide-containing electrolyte at −0.5 V vs. SCE. WO₃-TiO₂ composites were then synthesized under the same conditions, but with 0.2 g/L of anatase TiO₂ nanoparticles (⌀ 36 nm), mechanically suspended in the solution by stirring. After synthesis, the films were annealed at 400 °C. Structural characterization by XRD showed that the WO₃ films exhibit the crystalline structure of a non-stoichiometric hydrate, whereas, in WO₃-TiO₂, the WO₃ phase was monoclinic. The oxidation of tungsten, as revealed by XPS, was W⁶⁺ for both materials. Ti was found to exist mainly as Ti⁴⁺ in the composite, with a weak Ti³⁺ signal. The efficiency of the WO₃ films and composites as an oxygen evolution reaction (OER) photo-electrocatalyst was examined. The composite would generate approximately three times larger steady-state photocurrents at 1.2 V vs. SCE in a neutral 0.5 M Na₂SO₄ electrolyte compared to WO₃ alone. The surface recombination of photogenerated electron–hole pairs was characterized by intensity-modulated photocurrent spectroscopy (IMPS). Photogenerated charge transfer efficiencies were calculated from the spectra, and at 1.2 V vs. SCE, were 86.6% for WO₃ and 62% for WO₃-TiO₂. Therefore, the composite films suffered from relatively more surface recombination but generated larger photocurrents, which resulted in overall improved photoactivity. Full article

(This article belongs to the Special Issue Electrochemical Material Science and Electrode Processes)

► Show Figures

Graphical abstract

13 pages, 3920 KiB

Open AccessArticle

Recovery of Metal Ions (Cd²⁺, Co²⁺, and Ni²⁺) from Nitrate and Sulfate on Laser-Induced Graphene Film Using Applied Voltage and Its Application

by Xiu-man Wang, Tong Su and Yujun Chai

Materials 2024, 17(12), 2965; https://doi.org/10.3390/ma17122965 - 17 Jun 2024

Viewed by 726

Abstract

The urgent removal of Cd, Co, and Ni from nitrate and sulfate is essential to mitigate the potential risk of chemical pollution from large volumes of industrial wastewater. In this study, these metal ions were rapidly recovered through applying voltage on nitrate and [...] Read more.

The urgent removal of Cd, Co, and Ni from nitrate and sulfate is essential to mitigate the potential risk of chemical pollution from large volumes of industrial wastewater. In this study, these metal ions were rapidly recovered through applying voltage on nitrate and sulfate, utilizing laser-induced graphene/polyimide (LIG/PI) film as the electrode. Following the application of external voltage, both the pH value and conductivity of the solution undergo changes. Compared to Co²⁺ and Ni²⁺, Cd²⁺ exhibits a lower standard electrode potential and stronger reducibility. Consequently, in both nitrate and sulfate solutions, the reaction sequence follows the order of Cd²⁺ > Co²⁺ > Ni²⁺, with the corresponding electrode adsorption quantities in the order of Cd²⁺ > Co²⁺ ~ Ni²⁺. Additionally, using the recovered Co(OH)₂ as the raw material, a LiCoO₂ composite was prepared. The assembled battery with this composite exhibited a specific capacity of 122.8 mAh g⁻¹, meeting practical application requirements. This research has significance for fostering green development. Full article

(This article belongs to the Special Issue Electrochemical Material Science and Electrode Processes)

► Show Figures

Figure 1

22 pages, 3109 KiB

Open AccessEditor’s ChoiceArticle

Determination of Fluorine by Ion-Selective Electrode and High-Resolution Continuum Source Graphite Furnace Molecular Absorption Spectrometry with Respect to Animal Feed Safety

by Zofia Kowalewska, Karolina Goluch, Waldemar Korol, Rafał Olchowski and Ryszard Dobrowolski

Materials 2024, 17(12), 2812; https://doi.org/10.3390/ma17122812 - 9 Jun 2024

Viewed by 984

Abstract

Fluorine, depending on its concentration and chemical form, is essential or toxic to humans and animals. Therefore, it is crucial to be able to determine it reliably. In this study, fluorine was determined in animal feed after extraction with HCl (gastric juice simulation). [...] Read more.

Fluorine, depending on its concentration and chemical form, is essential or toxic to humans and animals. Therefore, it is crucial to be able to determine it reliably. In this study, fluorine was determined in animal feed after extraction with HCl (gastric juice simulation). The standard potentiometric method with a fluoride-selective electrode (ISE) and newly developed high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GFMAS) method was applied. Feed samples turned out to be a challenge for HR-CS GFMAS. Chemical interferences (formation of competing molecules, CaF, GaCl, and GaP, instead of the target GaF molecule) and spectral effects (including a phosphorous molecule spectrum and atomic lines) were identified. An additional difficulty was caused by reagent contamination with F and memory effects. Difficulties were eliminated/reduced. The quality of ISE analysis was multi-directionally verified (including comprehensive proficiency testing). A risk of inaccuracy at low F concentration, where the calibration relationship is nonlinear, was investigated. The results of both methods were consistent, which confirms the accuracy of the methods and informs that the extracted fluorine is in fluoride form. The results of extensive ISE tests conducted in Poland in 2021–2023 have shown that, in most cases, the fluoride content is significantly lower than the threshold values. Full article

(This article belongs to the Special Issue Electrochemical Material Science and Electrode Processes)

► Show Figures

Figure 1

11 pages, 1536 KiB

Open AccessArticle

Comparative Analysis of Metal Electrodeposition Rates towards Formation of High-Entropy WFeCoNiCu Alloy

by Tomasz Ratajczyk and Mikołaj Donten

Materials 2024, 17(7), 1513; https://doi.org/10.3390/ma17071513 - 27 Mar 2024

Viewed by 1011

Abstract

This study presents a calculation and comparison of Fe, Co, Ni and Cu deposition rates in the tungsten codeposition process based on the electrodeposition of numerous tungsten alloys. Eight different tungsten alloys containing from two to five metals were electrodeposited in constant conditions [...] Read more.

This study presents a calculation and comparison of Fe, Co, Ni and Cu deposition rates in the tungsten codeposition process based on the electrodeposition of numerous tungsten alloys. Eight different tungsten alloys containing from two to five metals were electrodeposited in constant conditions in order to compare the exact reduction rates. The calculated rates enabled control of the alloy composition precise enough to obtain a high-entropy WFeCoNiCu alloy with a well-balanced composition. The introduction of copper to form the quinternary alloy was found to catalyze the whole process, increasing the deposition rates of all the components of the high-entropy alloy. Full article

(This article belongs to the Special Issue Electrochemical Material Science and Electrode Processes)

► Show Figures

Figure 1

19 pages, 5398 KiB

Open AccessArticle

RETRACTED: Impact of High-Frequency Traveling-Wave Magnetic Fields on Low-Conductivity Liquids: Investigation and Potential Applications in the Chemical Industry

by Xinyu Cui, Xianzhao Na, Xiaodong Wang, Roland Ernst and Fautrelle Yves

Materials 2024, 17(4), 944; https://doi.org/10.3390/ma17040944 - 18 Feb 2024

Cited by 2 | Viewed by 1191 | Retraction

Abstract

High-frequency traveling-wave magnetic fields refer to alternating magnetic fields that propagate through space in a wave-like manner at high frequencies. These magnetic fields are characterized by their ability to generate driving forces and induce currents in conductive materials, such as liquids or metals. [...] Read more.

High-frequency traveling-wave magnetic fields refer to alternating magnetic fields that propagate through space in a wave-like manner at high frequencies. These magnetic fields are characterized by their ability to generate driving forces and induce currents in conductive materials, such as liquids or metals. This article investigates the application and approaches of a unique form of high-frequency traveling-wave magnetic fields to low-conductivity liquids with conductivity ranging from 1 to 102 S/m. Experiments were conducted using four representative electrolytic solutions commonly employed in the chemical industry: sulfuric acid (H₂SO₄), sodium hydroxide (NaOH), sodium chloride (NaCl), and ionic liquid ([Bmim]BF₄). The investigation focuses on the impact of high-frequency magnetic fields on these solutions at the optimal operating point of the system, considering the effects of Joule heating. The findings reveal that the high-frequency traveling magnetic field exerts a significant volumetric force on all four low-conductivity liquids. This technology, characterized by its non-contact and pollution-free nature, high efficiency, large driving volume, and rapid driving speeds (up to several centimeters per second), also provides uniform velocity distribution and notable thermal effects. It holds considerable promise for applications in the chemical industry, metallurgy, and other sectors where enhanced three-phase transfer processes are essential. Full article

(This article belongs to the Special Issue Electrochemical Material Science and Electrode Processes)

► Show Figures

Figure 1

13 pages, 4111 KiB

Open AccessEditor’s ChoiceArticle

Synergetic Effect and Phase Engineering by Formation of Ti₃C₂T_x Modified 2H/1T-MoSe₂ Composites for Enhanced HER

by Lei Xiao, Qichao Yang, Xiangyang Zhu, Yang Wei and Jing Wang

Materials 2023, 16(21), 6991; https://doi.org/10.3390/ma16216991 - 31 Oct 2023

Cited by 1 | Viewed by 1385

Abstract

The typical semi conductivity and few active sites of hydrogen evolution of 2H MoSe₂ severely restrict its electrocatalytic hydrogen evolution performance. At the same time, the 1T MoSe₂ has metal conductivity and plentiful hydrogen evolution sites, making it feasible to optimize [...] Read more.

The typical semi conductivity and few active sites of hydrogen evolution of 2H MoSe₂ severely restrict its electrocatalytic hydrogen evolution performance. At the same time, the 1T MoSe₂ has metal conductivity and plentiful hydrogen evolution sites, making it feasible to optimize the electrocatalytic hydrogen evolution behavior of MoSe₂ using phase engineering. In this study, we, through a simple one-step hydrothermal method, composed 1T/2H MoSe₂, and then used newly emerging transition metal carbides with several atomic-layer thicknesses Ti₃C₂T_x to improve the conductivity of a MoSe_2-based electrocatalyst. Finally, MoSe₂@Ti₃C₂T_x was successfully synthesized, according to the control of the additional amount of Ti₃C₂T_x, to form a proper MoSe₂/ Ti₃C₂T_x heterostructure with a better electrochemical HER performance. As obtained MoSe₂@4 mg-Ti₃C₂T_x achieved a low overpotential, a small Tafel slope and this work offers additional insight into broadened MoSe₂ and MXenes-based catalyst’s electrochemical application. Full article

(This article belongs to the Special Issue Electrochemical Material Science and Electrode Processes)

► Show Figures

Figure 1

13 pages, 5163 KiB

Open AccessEditor’s ChoiceArticle

Controlling the Cooling Rate of Hydrothermal Synthesis to Enhance the Supercapacitive Properties of β-Nickel Hydroxide Electrode Materials

by Yang-Ming Lu and Sheng-Huai Hong

Materials 2023, 16(16), 5576; https://doi.org/10.3390/ma16165576 - 11 Aug 2023

Cited by 1 | Viewed by 1199

Abstract

The demand for power storage devices with good quality, fast charging and high energy density is becoming more and more urgent in today’s electronic technology. For batteries and traditional capacitors, it is an insurmountable challenge to combine fast charging and discharging, large capacitance [...] Read more.

The demand for power storage devices with good quality, fast charging and high energy density is becoming more and more urgent in today’s electronic technology. For batteries and traditional capacitors, it is an insurmountable challenge to combine fast charging and discharging, large capacitance and long-life properties. The characteristics of supercapacitors can meet all the above requirements at the same time. In this study, a simple one-step hydrothermal method was successfully used to grow β-nickel hydroxide nanocone particles directly on the 3D foamed nickel substrate as a working electrode material for supercapacitors. After growing β-nickel hydroxide crystals on 3D foamed nickel substrate, by controlling the cooling rate, a well-crystalized β-nickel hydroxide with good capacitance characteristics can be obtained. Cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) were used to analyze the capacitance characteristics of the β-nickel hydroxide electrode. The research results show that the specific capacitance value of the β-Ni(OH)₂/3D nickel foam electrode material prepared at the cooling rate of 10 °C/h can reach 539 F/g with the charge–discharge test at a current density of 3 A/g. After 1000 continuous charge and discharge cycles, the material still retains 94.1% of the specific capacitance value. Full article

(This article belongs to the Special Issue Electrochemical Material Science and Electrode Processes)

► Show Figures

Figure 1

Review

Jump to: Research

15 pages, 2605 KiB

Open AccessEditor’s ChoiceReview

Divalent Metal Ion Depletion from Wastewater by RVC Cathodes: A Critical Review

by Alessandro Dell’Era, Carla Lupi, Erwin Ciro, Francesca A. Scaramuzzo and Mauro Pasquali

Materials 2024, 17(2), 464; https://doi.org/10.3390/ma17020464 - 18 Jan 2024

Viewed by 954

Abstract

In this paper, a critical review of results obtained using a reticulated vitreous carbon (RVC) three-dimensional cathode for the electrochemical depletion of various divalent ions, such as Cu⁺², Cd⁺², Pb⁺², Zn⁺², Ni⁺², and [...] Read more.

In this paper, a critical review of results obtained using a reticulated vitreous carbon (RVC) three-dimensional cathode for the electrochemical depletion of various divalent ions, such as Cu⁺², Cd⁺², Pb⁺², Zn⁺², Ni⁺², and Co⁺², often present in wastewater, has been carried out. By analyzing the kinetics and fluid dynamics of the process found in literature, a general dimensionless equation, Sh = f(Re), has been determined, describing a general trend for all the analyzed systems regardless of the geometry, dimensions, and starting conditions. Thus, a map in the log(Sh) vs. log(Re) plane has been reported by characterizing the whole ion electrochemical depletion process and highlighting the existence of a good correlation among all the results. Moreover, because in recent years, the interest in using this three-dimensional cathode material seems to have slowed, the intent is to revive it as a useful tool for metal recovery, recycling processes, and water treatments. Full article

(This article belongs to the Special Issue Electrochemical Material Science and Electrode Processes)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Electrochemical Material Science and Electrode Processes

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (8 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI