Cyclic Voltammetry Curves Research Articles

Supercritical fluid-assisted fabrication of CuxOSAS-based electrochemical sensor for cysteine detection with enhanced sensitivity and reduced oxidation potential

This work demonstrates a rapid and effective strategy to make a cysteine detection system with higher sensitivity and lower detection limit using an eco-friendly supercritical antisolvent (SAS) technology. Copper salt particles were prepared via SAS and transformed into copper(I/II) oxide (CuxOSAS) upon calcination at 400℃. The resulting calcinated product exhibited a significantly reduced particle size and the presence of mixed valence states. The fabricated CuxOSAS cysteine detection system demonstrated excellent performance, with a cyclic voltammetry (CV) curve displaying a low oxidative overpotential (∼0.1 V vs. Ag/AgCl). The linear detection range was 0.001 μM to 0.25 μM and 0.25 μM to 1000 μM, respectively, with corresponding sensitivity of 2447.1 μA·cm−2·μM−1 and 0.3714 μA·cm−2·μM−1, respectively. In conclusion, the SAS-prepared CuxOSAS hold great prospective for electro-sensing and biomolecular catalysis applications.

Microwave-assisted synthesis of P-doped and O-rich graphitic carbon catalyst for vanadium redox flow batteries

P-doped, O-rich graphitic carbon (POGC) was synthesized via an environmentally friendly, cost effective microwave (MW)-assisted treatment using a phytic acid precursor. The treatment facilitated the formation of coral-like clusters and barrel-like graphitic structures; the P-doped graphitic structures and P–C bonds increased with the increasing irradiation time. The irradiation process increased the graphitization degree of the P-doped structure, resulting in high catalytic activity toward vanadium ion redox reactions (VIRRs), as well as improved electrical conductivity. The optimal treatment time (60 s) for POGC (POGC-60) was determined by evaluating the cyclic voltammetry curves of VIRR using POGC. POGC-60 exhibited the highest peak current densities in the anolyte and catholyte, approximately three times higher than that of the control electrode. Additionally, POGC-60 significantly reduced the charge-transfer resistance, indicating a decrease in the overpotential of VIRR. Similar improvements (increased peak current densities, reduced potential differences, and reduced charge-transfer resistance) were observed when POGC was combined with commercial graphite felt (GF) electrodes, GF/POGC. The vanadium redox flow batteries (VRFBs) utilizing the GF/POGC electrodes demonstrated enhanced efficiencies and discharge capacities (even at high current densities), as well as exceptional long-cycle stability. These findings highlight MW irradiation as a commercially feasible option for achieving the facile manufacture of cost effective, outstanding, environmentally friendly catalysts for VRFBs.

INVESTIGATION OF THE MECHANISM OF LANTHANUM IONS ELECTROREDUCTION ON NICKEL ELECTRODE IN CHLORIDE MELT

The electrochemical behavior of lanthanum ions on a nickel electrode has been studied using various electrochemical methods such as cyclic voltammetry, chronopotentiometry, open circuit chronopotentiometry (on-off curves), and square wave voltammetry in an equimolar melt of potassium and sodium chlorides at 973 K. The cyclic voltammetry curves has several reduction waves on the cathodic branch and corresponding oxidation waves on the anodic branch. The first wave A is located in the potential region –(0.0–0.1) V, where the reduction of Ni2+ ions takes place. The second wave B is in the region of potentials –(1.72–1.77) V, on it occurs electroreduction of ions \({\text{LaCl}}_{6}^{{3 - }}\) on nickel electrode with certain depolarization with formation of intermetallide of lanthanum with nickel LaxNiy. The appearance of the third wave C in the potential region –(2.09–2.13) V, we associate with the electroreduction of chloride complexes \({\text{LaCl}}_{6}^{{3 - }}\) on intermetallide LaxNiy with the formation of metallic lanthanum. On the basis of the obtained data it is shown that during the electroreduction of lanthanum chloride complexes in KCl–NaCl melt at T = 973K the nickel electrode interacts with the released lanthanum, causing a significant depolarization of the process of electroreduction of the chloride complex, also formation of intermetallide with Ni electrode occurs.

NANOSTRUCTURED COMPOSITES BASED ON MATRICES OBTAINED FROM COAL RAW MATERIALS FOR DEVELOPMENT OF ELECTRODE MATERIALS FOR SUPERCAPACITORS

The article reports the results of the study of the morphology, porous structure and electrical capacitance characteristics of highly porous carbon matrices (HPCMs) obtained from coal raw materials with different degrees of metamorphism and nanostructured composites (NSCs) based on them, the surface of which is decorated with gold or manganese oxide nanosized particles (NP), accumulating electrical charge during polarization in the electrolyte via two mechanisms (formation of an electrical double layer (EDL) and involvement of pseudo-capacitance component during Red-Ox reactions on electrodes). The samples of HPCMs were obtained by high-temperature (800 °C) alkaline activation (the mass ratio KOH/C = 2 : 1) of fossil coal from the coal basins of the Kemerovo Region and the Republic of Sakha (Yakutia): CAK - based on anthracite of the Kiyzasskiy open-pit mine (Kuzbass), with the highest coalification degree; CBK - based on boghead (a kind of sapropel coal ) from the Taymylyr deposit (Yakutia) with the lowest degree of metamorphism; CDK - based on long-flame coal (Kuzbass) occupying an intermediate position in the metamorphism series. Results obtained by scanning electron microscopy, small-angle X-ray scattering in combination with sorptometry showed that the NSC morphology is largely determined (except for submicron aggregates) by the porous structure of the matrices. The shape of cyclic voltammetry (CVA) curves for HPCMs CDK, CBK and Au-NP filled NSC based on them indicated a significant contribution from EDL into capacitance; the contribution of pseudo-capacitance is observed for the composite MnOx/CDK electrode. The features of CVA curves for microporous CAK HPCM and NSC based on it are probably caused by hindered diffusion. The specific electrical capacitance is higher as a result of the polarization of CDK and CBK HPCM with large proportions of mesopores, as well as NSCs on their basis, than that resulting from the polarization of microporous CAK and the corresponding composites. For all three HPCMs, the introduction of fillers causes an increase in the electrode capacitance. The effect is more significant for NSCs obtained from hard coals with a low level of metamorphism (an increase up to 1.8 and 1.6 times with respect to the capacitance of initial matrices for NSCs based on CDK and CBK, respectively, according to the impedance measurement data), which is due to a decrease in the active resistance and the charge transfer resistance of the cells, and, in general, to the active component of the impedance.

The fabrication and in vitro bioactivity of HA/ZrO2/MgO gradient composite coatings

Hydroxyapatite (HA), chitosan (CS), ZrO2 and MgO suspensions were distributed by zonal electrophoresis (ZE), and then HA/CS/ZrO2/MgO composite coating on the surface of titanium substrate was fabricated by electrophoretic deposition (EPD) in a reverse electric field subsequently. An HA/ZrO2/MgO gradient composite coating (Z1) was fabricated by calcination at 700 °C for 120 min. At the same time, another HA/ZrO2/MgO composite coating (E1) was directly fabricated only by electrophoretic deposition for comparison, where ZrO2 and MgO were osteogenic trace element compounds (OTECs). The morphology, structure, composition, wettability, apatite-forming ability, antibacterial efficacy of the composite coating Z1 were investigated by XRD, FT-IR, FESEM, EDS, contact angle goniometry, Lloyd's universal testing machine, electrochemical workstation, immersing in simulated body fluid, and inhibition experiments. The results showed that the contents of Ca, Zr, and Mg elements had a gradient distribution in direction of coating thickness. With the addition of ZrO2 and MgO, the contact angle of Z1 is significantly reduced from 52.5° to 27.3°. Remarkably, Z1 has more improved properties than E1, mainly manifested in the bonding strength of Z1 and titanium substrate up to 29.3 MPa, exceeding the standard requirements for bonding strength of HA coating implants (15 Mpa, iso13779-2) and as can be observed from cyclic voltammetry (CV) curve and Tafel polarization curve, Z1 exhibit superior electrochemical stability and strong corrosion resistance when immersed in HEPES simulated body fluid (H–SBF). In addition, after immersing in H–SBF for 24 d, the surface of the Z1 was completely covered by carbonated hydroxyapatite (CHA) and the Ca/P of the coating increased from 1.67 to 1.99. Furthermore, the antibacterial effect test of Z1 showed that the antibacterial rates of Z1 against Escherichia coli and Staphylococcus aureus reached to 98.2 % and 86.3 %, respectively.

Determination of heavy metals in rice (Oryza sativa L.) and soil using AuNP/BiNP/MWCNT/Nafion modified glassy carbon electrode

This paper presents the fabrication and application of a gold nanoparticle (AuNP)/bismuth nanoparticle (BiNP)/multi-walled carbon nanotubes (MWCNT)/Nafion-modified glassy carbon electrode for the determination of lead (Pb) and cadmium (Cd) via anodic stripping voltammetry (ASV). The ASV parameters as well as the AuNP and BiNP contents of the electrode modifier were optimized. The surface morphology, elemental composition, and electrochemical performance of the modified electrode were characterized using scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), and cyclic voltammetry (CV), respectively. The SEM and EDX results showed that the modifiers were present on the electrode surface, while the CV curves show the remarkable stability of the modified electrode. The limit of detection of the fabricated electrode is 2.20 ppb for cadmium and 0.58 ppb for lead. Real sample analysis was performed using rice plant parts: husk, grain, stalk, leaf, root, and soil where the rice plant was planted. The fabricated electrode was able to detect trace concentrations of Pb and Cd in the said samples.

Rheological and Electrochemical Properties of Biodegradable Chia Mucilage Gel Electrolyte Applied to Supercapacitor

The flexible energy storage device of high demand in wearable and portable electronics. Flexible supercapacitors have benefits over flexible batteries, and their development relies on the use of flexible components. Gel polymer electrolytes have the merits of liquid and solid electrolytes and are used in flexible devices. In this study, a gel derived from chia seed was used as a flexible electrolyte material, and its rheological, thermal, and electrochemical properties were investigated. High thermal stability and shear thinning behavior were observed via the electrolyte state of the chia mucilage gel. Compared to the conventional salt electrolyte, the chia mucilage gel electrolyte-based supercapacitor exhibited a more rectangular cyclic voltammetry (CV) curve, longer discharging time in galvanostatic charge–discharge (GCD) analysis, and low charge transfer resistance in electrochemical impedance spectroscopy (EIS). The maximum specific capacitance of 7.77 F g−1 and power density of 287.7 W kg−1 were measured, and stable capacitance retention of 94% was achieved after 10,000 cycles of charge/discharge with harsh input conditions. The biodegradability was also confirmed by the degraded mucilage film in soil after 30 days. The plant-driven chia mucilage gel electrolyte can facilitate the realization of flexible supercapacitors for the energy storage devices of the future.

Pseudocapacitive lithium-rich disordered rock salt vanadium oxide with 3D lithium-ion transport pathways for high-performance lithium-ion capacitor

Pseudocapacitive materials with high-rate behavior of lithium-ion charge storage offer a pathway to narrow the kinetics gap with capacitive porous carbon cathode toward lithium-ion capacitors both with high energy and high power densities. However, most of pseudocapacitive materials are subject to their relatively high redox potential, thus resulting in an undesirable decrease in energy density. Here, we demonstrate that lithium-rich disordered rock salt vanadium oxide (DRX-Li3V2O5), electrochemically transformed from V2O5 bulk, exhibits typical pseudocapacitive behaviors within a low working potential range between 0.1 and 2.0 V (vs. Li/Li+). The pseudocapacitive behaviors of DRX-Li3V2O5 mainly arise upon a percolating network that offers three-dimensional Li + transport pathways confirmed by Monte Carlo simulations. When the V2O5 bulk precursor is replaced by V2O5 nanosheets, as-obtained DRX-Li3V2O5 electrode displays a nearly symmetrical cyclic voltammetry curve, suggesting an ideal pseudocapacitive behavior. A lithium-ion capacitor further assembled by this pseudocapacitive DRX-Li3V2O5 anode, yields a cell voltage of 4.0 V, a maximum energy density of 186 Wh kg−1 and a maximum power density of 51,680 W kg−1 as well as long-term cycling life over 30,000 cycles, which are higher than or comparable to that of the state-of-art lithium-ion capacitors based on graphite and other pseudocapacitive materials.

Design and Performance of a New Zn0.5Mg0.5FeMnO4 Porous Spinel as Anode Material for Li-Ion Batteries.

Due to the low capacity, low working potential, and lithium coating at fast charging rates of graphite material as an anode for Li-ion batteries (LIBs), it is necessary to develop novel anode materials for LIBs with higher capacity, excellent electrochemical stability, and good safety. Among different transition-metal oxides, AB2O4 spinel oxides are promising anode materials for LIBs due to their high theoretical capacities, environmental friendliness, high abundance, and low cost. In this work, a novel, porous Zn0.5Mg0.5FeMnO4 spinel oxide was successfully prepared via the sol-gel method and then studied as an anode material for Li-ion batteries (LIBs). Its crystal structure, morphology, and electrochemical properties were, respectively, analyzed through X-ray diffraction, high-resolution scanning electron microscopy, and cyclic voltammetry/galvanostatic discharge/charge measurements. From the X-ray diffraction, Zn0.5Mg0.5FeMnO4 spinel oxide was found to crystallize in the cubic structure with Fd3¯m symmetry. However, the Zn0.5Mg0.5FeMnO4 spinel oxide exhibited a porous morphology formed by interconnected 3D nanoparticles. The porous Zn0.5Mg0.5FeMnO4 anode showed good cycling stability in its capacity during the initial 40 cycles with a retention capacity of 484.1 mAh g-1 after 40 cycles at a current density of 150 mA g-1, followed by a gradual decrease in the range of 40-80 cycles, which led to reaching a specific capacity close to 300.0 mAh g-1 after 80 cycles. The electrochemical reactions of the lithiation/delithiation processes and the lithium-ion storage mechanism are discussed and extracted from the cyclic voltammetry curves.

Synthesis of silicon nanoparticles with various additions of inert salt as scavenger agent during reduction by the magnesiothermic method as anode lithium-ion batteries

A heat scavenger agent magnesiothermic reduction of quartz sand was used to make Si nanoparticles in a way that can be easily scaled up. Its source of SiO2 is safe for the environment, easy to get, and cheap. It can make silicon nanoparticles that work well as an anode material for Li-ion batteries. It is known that using inert salt NaCl has a better characterization of Si and electrochemical performance than KCl, KBr, and CaCl2. XRD diffractogram show 2θ are formed at 27.42°, 47.30°, 56.11°, 69.19°, and 76.37°. The surface area shows 9.75 m2/g, and the pore size is 15.35 Å. In the TEM images, it is found that the silicon shape is spherical. The electrical conductivity voltage of 1 V is 2599.33 µS/cm. The cyclic voltammetry curve during the highest oxidation is 0.57 V, and the lowest oxidation peak is 0.16 V. After the first cycle, the Rs is 4.22 Ω, and the Rct formed is 51.19 Ω. The first discharge capacity is 2599.57 mAh/g, corresponding to coulombic efficiencies at 97.12 %.

Electro-deposited halloysite nanotube/polyaniline nanocomposites for energy storage applications

A nanocomposite (nanoclay/conductive polymer) was prepared by a template-free method for supercapacitor applications. Halloysite Nanotubes (HNTs) were used as a nanoclay material, and synthesized polyaniline (PANI) by ammonium persulfate-initiated polymerization was used as a conductive polymer. The HNTs/PANI nanocomposite was deposited on an indium tin oxide (ITO) coated glass to obtain a working electrode by an electrochemical deposition method. Morphological and structural examination of the HNTs/PANI nanocomposite proved that the PANI nanoparticles were attached to the HNTs surface. The structural analysis demonstrated that the PANI and HNTs crystal size significantly decreased in the HNTs/PANI as a result of the composition of PANI molecules with HNTs structure. The main characteristic bonds and functional groups of HNT, PANI, and HNTs/PANI nanocomposites were determined by FT-IR analysis. Using cyclic voltammetry (CV), the electrochemical performance of the HNTs//PANI nanocomposite electrode was investigated. The specific capacitance values were reported via the CV curves as 264, 230.22, 175.2, and 154.8 F/g at scan rates of 50, 100, 200, and 300 mV/s respectively. The results showed that the specific capacitance at the slow scan rates revealed higher maximum specific capacitance values.

Graphene aerogel-supported Na3V2(PO4)3/C cathodes for sodium-ion batteries

Na3V2(PO4)3 (NVP) is a preferred cathode material for Na-ion batteries due to its good thermal stability and long cycle life, but its low electrical conductivity limits its use. The carbon coating method is widely available in the literature but can solve the problem to a limited extent. Graphene aerogel-based composite materials with lightweight, high surface area and 3-dimensional (3D) porous structure are prepared, and the properties are tried to be improved further. In this study, carbon-coated Na3V2(PO4)3 (NVP/C) and graphene aerogel-carbon-coated Na3V2(PO4)3 (GA-NVP/C) composite have been synthesized. The produced samples have been analyzed using Field emission scanning electron microscopy, X-ray diffraction, Raman spectrum, Thermal Gravity Analysis, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller and Transmission electron microscopy. Then, the effect of graphene aerogel additive on electrochemical performances as cathode materials has been investigated. Even though GA-NVP/C and NVP/C have similar discharge capacities in the first cycle, GA-NVP/C shows high cycle stability when compared to NVP/C after 250 cycles. The GA-NVP/C cathode also has a higher discharge capacity than the NVP/C cathode at different current rates. The diffusion coefficient calculated using the cyclic voltammetry curve of GA-NVP/C is also high, supporting the graphene aerogel's positive results. In conclusion, we show that adding GA with a 3-dimensional porous structure greatly improves the electrochemical properties of the cathode in Na-ion batteries.

Smart Target-Initiated Catalytic DNA Junction Circuit Amplification Strategy for the Ultrasensitive Electrochemiluminescence Detection of MicroRNA.

One of the highly attractive research directions in the electrochemiluminescence (ECL) field is how to regulate and improve ECL efficiency. Quantum dots (QDs) are highly promising ECL materials due to their adjustable luminescence size and strong luminous efficiency. MoS2 NSs@QDs, an ECL emitter, is synthesized via hydrothermal methods, and its ECL mechanism is investigated using cyclic voltammetry and ECL-potential curves. Then, a stable and vertical attachment of a triplex DNA (tsDNA) probe to the MoS2 nanosheets (NSs) is applied to the electrode. Next, an innovative ECL sensor is courageously empoldered for precise and ultrasensitive detection of target miRNA-199a through the agency of ECL-resonance energy transfer (RET) strategy and a dextrous target-initiated catalytic three-arm DNA junction assembly (CTDJA) based on a toehold strand displacement reaction (TSDR) signal amplification approach. Impressively, the ingenious system not only precisely regulates the distance between energy donor-acceptor pairs leave energy less loss and more ECL-RET efficiency, but also simplifies the operational procedure and verifies the feasibility of this self-assembly process without human intervention. This study can expand MoS2 NSs@QDs utilization in ECL biosensing applications, and the proposed nucleic acid amplification strategy can become a miracle cure for ultrasensitive detecting diverse biomarkers, which helps researchers to better study the tumor mechanism, thereby unambiguously increasing cancer cure rates and reducing the risk of recurrence.

MnO2/La2O3/rGO composite catalyst prepared by electrodeposition as corona discharge anode for electrocatalytic cracking of toluene

To achieve the purification of coke oven gas and pyrolysis gas under oxygen-free conditions, the MnO2/La2O3/rGO composite catalyst was innovatively loaded directly onto the surface of porous titanium mesh anode by electrodeposition in this study, together with corona discharge for toluene cracking. During the catalyst preparation, the effects of potential and pH on the catalyst were verified in combination with cyclic voltammetry (CV) curves. The results showed that the toluene cracking rate reached 90% at 7 kV when the electrolyte concentrations of Mn2+, La3+ and rGO were 0.1 mol/L, 0.05 mol/L and 0.005 g/L, respectively. In addition, in this study, the distribution and changes of potential and electron temperature inside the reactor were simulated by COMSOL, and the concentration and change pattern of positive and negative ions at 7 kV were calculated. The results showed that both the plasma and the catalyst play a very significant role in this process.

Facile synthesis of dysprosium oxide/bismuth oxide nanocomposite electrode materials with good electrocatalytic performance

Background: Benzoic acid is widely applied in the food field, including beverages as the antimicrobial preservative due to its strong inhabitation role to bacteria and yeasts. However, excessive intake of benzoic acid can easily cause abdominal pain and diarrhea and can even result in metabolic diseases. Hence, it is important to seek simple, accurate and sensitive strategies to detect low-trace benzoic acid. Objective: The aim of this study is to synthesize dysprosium oxide/bismuth oxide nanocomposites using dysprosium sulphate and sodium bismuthate as the raw materials and research the electrochemical sensing properties for the detection of benzoic acid. Methods: Dysprosium oxide/bismuth oxide nanocomposites were synthesized by a facile hydrothermal route. The dysprosium oxide/bismuth oxide nanocomposites were characterized by X-ray diffraction, electron microscopy, X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy. Results: The dysprosium oxide/bismuth oxide nanocomposites are composed of nearly circular-shaped particles with polycrystalline cubic Dy2O3 and triclinic Bi2O3 phases. The size of the nearly circular-shaped particles is about 50 to 200 nm. The electrons are easier to transfer by the dysprosium oxide/bismuth oxide nanocomposite-modified electrode than the bare electrode. A pair of quasi-reversible cyclic voltammetry (CV) peaks located at -0.155 V and -0.582 V exist in the CV curve of 0.1 M KCl buffer solution containing 2 mM benzoic acid. The nanocomposite-modified electrode shows a linear detection range and detection limit of 0.001-2 mM and 0.18 μM, respectively, for benzoic acid detection. Conclusion: The dysprosium oxide/bismuth oxide nanocomposite-modified electrode reveals superior electro-catalytic activity towards benzoic acid.

(Invited) 2D Mxenes for Energy Storage Applications

MXenes are a family of two-dimensional (2D) transition metal carbides and nitrides, with a general structure of Mn+1XnT x , where M is the transition metal, X is carbon and/or nitrogen, and T represents the surface terminations (F, O, OH). MXenes have attracted attention in a multitude of energy storage applications due to their high electronic conductivity, tunable interlayer spacing, redox-active transition metals, and hydrophilic surface groups. In this talk, we discuss the use of MXene electrodes in supercapacitor applications, including aqueous, non-aqueous, and water-in-salt electrolytes. The variability of MXenes is demonstrated with each electrolyte system showing unique electrochemical responses, not limited to redox and/or intercalation pseudocapacitance, and hydrated cation intercalation. Furthermore, the versatility of the hydrophilic, 2D morphology of MXenes is demonstrated through its use in multiple form factors, not limited to flexible free-standing films, multilayer powder electrodes, interdigitated microsupercapacitors, knitted textiles, and more. New directions and perspectives for MXenes in energy storage are discussed, including MXenes’ use as passive components (separators, current collectors, binders, scaffolds, conductive additives) in energy storage systems. Figure 1 (A) Schematic illustration showing MXenes’ electrochemical properties for ion storage applications. (B) Cyclic voltammetry (CV) data collected at scan rates from 10 to 100,000 mV·s−1 for a 90-nm-thick Ti3C2T x film. (C) Influence of an electrolyte’s solvent on the lithium-ion storage capacity of Ti3C2T x ; CV curves of microporous Ti3C2T x electrode in 1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in DMSO, acetonitrile (ACN), or propylene carbonate (PC) electrolytes. (D) A digital photograph showing the wafer scale fabrication of an array of 143 MXene microsupercapacitors. (E) Photograph of a knitted textile with an interdigitated pattern made using Ti3C2T x MXene-coated cotton yarn to produce electrodes for wearable textile supercapacitor.Reference[1] A. VahidMohammadi, J. Rosen, Y. Gogotsi, Science, 2021, 372, eabf1581. Figure 1

Simultaneous naphthalene degradation and electricity production in a biowaste-powered microbial fuel cell

Naphthalene is a very common and hazardous environmental pollutant, and its biodegradation has received serious attention. As demonstrated in this study, naphthalene-contaminated wastewater can be biodegraded using a microbial fuel cell (MFC). Furthermore, the potential of MFC for electricity generation appears to be a promising technology to meet energy demands other than those produced from fossil fuels. Nowadays, efforts are being made to improve the overall performance of MFC by integrating biowaste materials for anode fabrication. In this study, palm kernel shell waste was used to produce palm kernel shell-derived graphene oxide (PKS-GO) and palm kernel shell-derived reduced graphene oxide (PKS-rGO), which were then fabricated into anode electrodes to improve the system's electron mobilization and transport. The MFC configuration with the PKS-rGO anode demonstrated greater energy production potential, with a maximum power density of 35.11 mW/m2 and a current density of 101.76 mA/m2, compared to the PKS-GO anode, which achieved a maximum power density of 17.85 mW/m2 and a current density of 72.56 mA/m2. Furthermore, there is simultaneous naphthalene biodegradation with energy production, where the biodegradation efficiency of naphthalene with PKS-rGO and PKS-GO is 85.5%, and 79.7%, respectively. In addition, the specific capacitance determined from the cyclic voltammetry curve revealed a value for PKS-rGO of 2.23 × 10−4 F/g, which is also higher than the value for PKS-GO (1.57 × 10−4 F/g) on the last day of operation. Anodic microbial analysis shows that electrogens thrive in the MFC process. Finally, a comparison with previous literature and the future prospects of the study are also presented.

A multiphase coupling strategy to structurally stable manganese-based oxides cathode for high electrochemical performance sodium ion batteries

Manganese (Mn) based oxides attract extensive attention as cathode materials for sodium (Na) ion batteries (SIBs) due to their high theoretical capacity and low cost. However, the Jahn-Teller distortion caused by the Mn (III) center and the phase transition of P2-O2 at high voltage (>4.0 V) limits its practical applications. In this work, a multiphase coupling scheme involving Na0.7MnO2.05 (P2), Na0.44MnO2 (T), and Na0.91MnO2 (Z) is presented to develop improved and available Mn based oxides cathode for superior electrochemical performance SIBs via solid state method. It is found that the optimal coupling at the molecular and atomic levels can be achieved by adjusting the regulation of morphology and grain size of the multiphase, which possesses larger interlayer spacing and fewer Mn3+ ions to suppress the Jahn-Teller lattice distortion of Mn3+ as well as the phase transition of P2-O2 at high voltage (>4.0 V). As a result, the as-prepared cathode delivers a high discharge specific capacity of 183.28 mA h g−1 at a rate of 0.5 C with a high-capacity retention of 77.2% after 100 cycles. Moreover, it also shows the fastest Na+ diffusion ability and kinetics properties, which is revealed by refined analysis of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) curves. This study presents a straightforward and scalable approach for developing novel cathode materials based on Mn oxides with excellent performance in sodium-ion batteries (SIBs).

Optimization of ammonia and COD removal from municipal wastewater effluent by electrochemical continuous flow reactor equipped with Ti/RuO2 and Cu foam

The aim of the present work was to study an electrochemical continuous-flow reactor for the removal of ammonia nitrogen (NH4+N), its by-product, and Chemical Oxygen Demand (COD) from synthetic and real municipal wastewater effluent. In this study, Ti/RuO2 electrode was prepared by the thermal decomposition method for the removal of NH4-N and COD. Characterization of the Ti/RuO2 was accomplished using FE-SEM, EDS, AFM, and XRD. Cyclic voltammetry and Tafel curves were used for the electrochemical feature of the Ti/RuO2 electrode. Box-Behnken Design (BBD) method was used to optimize the operating conditions. The effects of four independent parameters including the initial concentration of NH4+ (10–30 mg/L as N), Cl− concentration (100–500 mg/L), HRT (30–100 min), and current (0.4–1.4 A) were examined using continuous experiments for the removal of NH4+N and COD. Characterization results confirmed that RuO2 was successfully coated on the surface of titanium mesh. Optimum conditions for Cl− concentration, HRT, and current were 490 mg/L, 100 min, and 1.36 A, respectively for an effluent concentration of 30 mg/L NH4+N and 30 mg/L of COD. Under these conditions, the removal efficiencies of NH4+N and COD were respectively 97.79 and 89.64 %, and the concentration of NO3−N was 1.93 mg/L. This work highlights the importance of an electrochemical continuous flow reactor for further removal of nitrogen and COD from the effluent of municipal wastewater treatment plants.

Unleashing the potential of eco-friendly chitosan: Methylcellulose polyblend electrolytes via magnesium acetate doping for solid state batteries

The most popular choice for inexpensive and energy-efficient storage devices has been solid biodegradable polymer electrolyte systems. In this study, chitosan (CS), methylcellulose (MC), and magnesium acetate (Mg(CH3COO)2) salt were mixed to create magnesium ion conducting solid blend polymer electrolyte (SBPE) membranes. The X-ray diffraction (XRD) study exhibited a variation in microstructure due to the addition of Mg(CH3COO)2 salt to the poly-blend matrix, which was also confirmed by Fourier transform infrared (FTIR) spectroscopy. Electrochemical impedance analysis revealed the maximum ionic conductivity of 2.24 × 10−5 S cm−1 for the electrolyte film comprising 30 wt% of Mg(CH3COO)2. The ionic transference number (tion) of about 0.88 was observed for the same salt concentration, indicating the predominance of ions as charge carriers in the SBPE. Electrochemical analyses exhibited maximum electrochemical stability window (ESW) for the highest conducting sample, thus incorporating it as a separator-cum-electrolyte. The oxidation and reduction peaks are observed in the cyclic voltammetry curve of the highest conducting sample. The discharge characteristic profiles of electrochemical cells in the configuration Mg/(CS + MC + Mg(CH3COO)2)/cathode with three different types of cathode materials to explore the synergic effect between electrode and poly-blend electrolyte was studied.