Linear Sweep Research Articles

3D Nickel–Manganese bimetallic electrocatalysts for an enhanced hydrogen evolution reaction performance in simulated seawater/alkaline natural seawater

In this paper, we report an inexpensive one-step synthesis of self-supported 3D nickel-manganese (NiMn) bimetallic coatings and their application for the hydrogen evolution reaction in simulated seawater (1 M KOH + 0.5 M NaCl) and alkaline natural seawater (1 M KOH + natural seawater). These binary coatings were electrodeposited on a titanium substrate using a facile electrochemical deposition method by a dynamic hydrogen bubble template technique. The as-deposited NiMn coatings with variable Mn amounts produce typical globular and unique porous architecture with abundant pores of different sizes. The activity of these fabricated catalysts towards the hydrogen evolution reaction was investigated by linear sweep voltammetry towards simulated seawater and alkaline natural seawater at different temperatures. The surface morphology and composition of the catalysts were also characterized by scanning electron microscopy and inductively coupled plasma optical emission spectroscopy. The as-prepared NiMn/Ti electrocatalyst, which was electrodeposited using a chemical bath containing Ni2+ and Mn2+ ions with a molar ratio of Ni2+:Mn2+ = 1:5, exhibits excellent hydrogen evolution activity in simulated seawater with an ultra-low overpotential of 64.2 mV to reach a current density of 10 mA cm−2. It is noteworthy that this NiMn/Ti electrocatalyst also achieves a current density of 10 mA cm−2 in alkaline natural seawater with a comparably low overpotential of 79.3 mV. The current densities increase by ca. 1.75–2.35 times with an increase in temperature from 25 °C to 75 °C for hydrogen evolution in both electrolytes. This bimetallic catalyst has shown excellent long-term stability at a constant potential of −0.23 V (vs. RHE) and a constant current density of 10 mA cm−2 for 10 h, which ensures higher durability and robustness for practical application of seawater splitting technology.

Genuine differential voltammetry

A novel form of differential voltammetry is proposed, developed through the implicit anodic and cathodic current components of the experimentally accessible conventional net current measured in a voltammetric experiment. By employing basic mathematical modelling of an electrode reaction of a dissolved redox couple at a conventional, macroscopic electrode within the framework of the Butler-Volmer electrode kinetic model, the implicit anodic and cathodic current components of the net conventional current are clearly defined and can be estimated. Consequently, a novel form of differential current, calculated as the difference between anodic and cathodic implicit current components associated with a single potential of the voltammetric experiment, can be established. This differential current demonstrates remarkable characteristics in terms of electrode kinetics and analytical performance, particularly in cases involving fast, seemingly electrochemically reversible electrode processes. It holds promise to be analytically superior to the best-known differential voltammetric techniques so far (e.g., square-wave voltammetry), as well as provides a means for estimating the rate constants of very fast, apparently reversible electrode processes at macroscopic electrodes under mild experimental conditions (i.e., studied at slow potential scan rates). The practical implication of the novel methodology is significant: a simple linear sweep voltammogram of a quasi-reversible electrode reaction with unknown electrode kinetic parameters can be readily transformed into the novel type of differential voltammogram through a convolution procedure of the conventional net current, paving a new way for studying electrode processes by voltammetry.

Application of fungal-based microbial fuel cells for biodegradation of pharmaceuticals: Comparative study of individual vs. mixed contaminant solutions

The present study focuses on the application of fungal-based microbial fuel cells (FMFC) for the degradation of organic pollutants including Acetaminophen (APAP), Para-aminophenol (PAP), Sulfanilamide (SFA), and finally Methylene Blue (MB). The objective is to investigate the patterns of degradation (both individually and as a mixture solution) of the four compounds in response to fungal metabolic processes, with an emphasis on evaluating the possibility of generating energy. Linear Sweep Voltammetry (LSV) has been used for electrochemical analysis of the targeted compounds on a Glassy Carbon Electrode (GCE). A dual chamber MFC has been applied wherein the cathodic compartment, the reduction reaction of oxygen was catalyzed by an elaborated biofilm of Trametes trogii, and the anodic chamber consists of a mixed solution of 200 mg L−1 APAP, PAP, MB, and SFA in 0.1 M PBS and an elaborated biofilm of Trichoderma harzianum. The obtained results showed that all the tested molecules were degraded over time by the Trichoderma harzianum. The biodegradation kinetics of all the tested molecules were found to be in the pseudo-first-order. The results of half-lives and the degradation rate reveal that APAP in its individual form degrades relatively slower (0.0213 h−1) and has a half-life of 33 h compared to its degradation in a mixed solution with a half-life of 20 h. SFA showed the longest half-life in the mixed condition (98 h) which is the opposite of its degradation as individual molecules (20 h) as the fastest molecule compared to other pollutants. The maximum power density of the developed MFC dropped from 0.65 mW m−2 to 0.32 mW m−2 after 45.5 h, showing that the decrease of the residual concentration of molecules in the anodic compartment leads to the decrease of the MFC performance.

Assessing correlations between two linear amplitude sweep (LAS) standards for evaluating the fatigue properties of aged bitumen

ABSTRACT Linear amplitude sweep (LAS) is an accelerated and well-established testing method to evaluate bitumen fatigue. However, there are different versions of LAS procedures employed. Significant differences in loading modes, damage failure criteria and calculations exist between existing standards, leading to the inconsistency in the performance characterisation of bitumen. This study investigated the fatigue performance of six different bitumen at various ageing levels using two versions of the LAS standards (TP101-14 and T391-20). The stress–strain curves, damage characteristic curves, prediction of fatigue life and cracking length were analysed and compared. It was seen that conclusions drawn from the old version of LAS standard (TP101-14) were unclear as no distinct trends related to change in fatigue life could be observed for binders with progressively increased ageing levels, regardless of the strain levels used for analysis. The new version of LAS (T391-20), however, showed acceptable consistency. The trends indicate that at low strain levels, the fatigue life increases with ageing levels, while opposite trend was observed at higher strain levels. Moreover, the cracking length as defined in the T391-20 standard increases with progressively increased ageing. The new version of LAS standard (T391-20) is recommended for characterising the fatigue performance of aged bitumen.

Utilization of Nanocenospheres a waste material to improve the physical and rheological properties of SBS asphalt binders

The performance enhancement of asphalt binders by incorporating innovative additives has been a subject of significant research and industry interest. This study emphasizes the potential of Nano polymer composites as a promising additive for improving the performance of asphalt binders, providing valuable insights into developing advanced asphalt materials for sustainable road infrastructure construction and maintenance. It explores the utilization of nano cenospheres to amplify the attributes of Styrene-Butadiene-Styrene (SBS) modified asphalt binders. It introduces a novel approach by incorporating Nano polymer composites (NPC) comprising nanocenosphere particles and Styrene-butadiene-Styrene Particles. Nanocenosphere particles are the waste materials derived from coal combustion in thermal power plants. Styrene-butadiene-styrene is a type of thermoplastic elastomer, a synthetic rubber. A series of experimental tests, penetration, softening point, ductility, performance grading, temperature sweep, multiple stress and creep recovery, frequency sweep, linear amplitude sweep, and rutting aging index, is conducted to evaluate changes in physical and rheological properties. Results indicate that adding nano cenospheres particles in SBS asphalt binder enhances its softening point, elasticity recovery, rutting resistance, fatigue life, storage stability, and aging resistance compared to traditional SBS-modified asphalt binders. Statistical analyses were accomplished to comprehend the influence of the Nano polymer composites. This analysis provides valuable insights into the effects of nanocenospheres on SBS-modified binders. Through rigorous statistical analysis, a thorough interpretation of how the incorporation of nanocenospheres influences the attributes of Nano-polymer composites.

Microwave initiated synthesis of carbon nanosphere from plastic and its application as anode electrocatalyst support in direct methanol fuel cell

The term plastisphere was coined to describe the human-made plastic environment, addressing the challenges of plastic waste. This study presents a rapid method using microwave susceptor catalysts (Co/Mo/Biochar, Ni/Mo/Biochar, Fe/Mo/Biochar) for the catalytic degradation of polystyrene into valuable carbon in microwave synthesizer. Using SEM, we found that active metal nanoparticles are uniformly distributed and the sizes of the active porous sites varied depending upon the catalyst used where the porous active sites of catalyst Co/Mo/biochar, Ni/Mo/biochar and Fe/Mo/biochar ranges between 300 nm and 700 nm, 2.21 μm and 4.05 μm, and 5 μm to larger pore size respectively. The microwave initiated catalytic synthesis process transforms uniform-sized polystyrene pellets into carbon nanospheres within 90 s. From XRD characterization, the broadened peaks at (002) plane resulted from the graphitic flakes' waving structure, confirming that the carbon nanospheres formed are graphitic in nature which is in agreement with results obtained from Raman spectroscopy. This study also explores polystyrene as an energy feedstock, utilizing Co/Mo/Biochar synthesized carbon nanospheres (CNS) which is mesoporous in nature with BET average surface area about 1428.3 m2/g as anode electro catalyst support for methanol oxidation in direct methanol fuel cells. The Pt Ru (1:1) supported on CNS catalyst exhibited higher electro catalytic activity compared to commercial PtRu/C, as indicated by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS).

A vertically aligned flake like CuO/Co3O4 nanoparticle@g-C3N4 ternary nanocomposite: A heterojunction catalyst for efficient photo electrochemical water splitting

Efficient utilization of solar energy for the conversion of water into hydrogen via photoelectrochemical (PEC) water splitting holds tremendous promise for sustainable energy production. In this study, we report a novel vertically aligned flake-like CuO/Co3O4 nanoparticle@g-C3N4 sheets ternary nanocomposite as a heterojunction catalyst for enhancing PEC water splitting efficiency. The ternary nanocomposite was synthesized via a facile and scalable method, resulting in a unique structure with vertically aligned CuO/Co3O4 nanoparticles in tight interface interaction with g-C3N4 sheets. The resulting heterojunction exhibited enhanced light absorption, efficient charge separation, and improved charge transfer kinetics, leading to significantly enhanced PEC water splitting performance. The as-synthesized ternary nanocomposite, such as CuO/Co3O4@g-C3N4 nanocomposite, demonstrated superior PEC activity with an enhanced photocurrent density, i.e., 0.88 mA/cm2, which is higher than that of the pristine CuO (0.65 mA/cm2), Co3O4 (0.7 mA/cm2), and CuO-Co3O4 (0.77 mA/cm2) structures with linear sweep voltammetry under light irradiation. Additionally, the ternary nanocomposite exhibited excellent stability during 2 h PEC water splitting measurements under 1 h time interval chopped conditions. The remarkable performance of the vertically aligned CuO/Co3O4 nanoparticle@g-C3N4 ternary nanocomposite underscores its potential as a promising catalyst for efficient solar-driven hydrogen generation. This study not only provides insights into the design of advanced heterojunction catalysts but also contributes to the development of sustainable energy conversion technologies.

Layered -bismuthene maximizes the active sites in Bi2Te3 towards electrocatalytic hydrogen evolution reactions

The need of sustainable energy sources drives the development of efficient hydrogen evolution reaction (HER) catalysts, inspiring innovative approaches to boost catalytic performance. Here, we introduce a method harnessing the unique properties of layered bismuthene to enhance the active sites of Bi2Te3. Through comprehensive characterization using XRD, FTIR, SEM, TEM, XPS, and Raman analysis, we elucidate the structural and morphological features of the synthesized material. Electrochemical assessments by employing cyclic voltammetry, linear sweep voltammetry, electrochemical impedance spectroscopy, and chronoamperometry techniques reveal the superior electrocatalytic performance of bismuthene incorporated Bi2Te3 composite, characterized by reduced overpotential (119 mV vs RHE at −10 mA/cm2) and Tafel slope (95.4 mV/dec). These findings underscore the efficacy of a few layered bismuthene in enhancing hydrogen production activity, particularly in alkaline environments, for sustainable water splitting processes. Our work presents findings that contribute to the development of catalysts which are scalable, eco-friendly and promise to revolutionize renewable energy technologies, paving the way for a cleaner and more accessible era of hydrogen fuel.

Adhesion promotion and corrosion resistance of mixed phosphonic acid monolayers on AA 2024

Mixed monolayers were used to prepare surfaces of AA 2024 with precisely controlled corrosion protective and adhesive properties. In this study, the corrosion inhibition and adhesion promotion as a function of the composition of mixed phosphonic acid monolayers on AA 2024 was investigated. Mixed monolayers were formed by competitive adsorption of n-dodecylphosphonic acid (DPA) and 12-aminododecylphosphonic acid (ADPA) from ethanolic solution. Their compositions were determined by X-ray photoelectron spectroscopy. Atomic force microscopy studies and polarization modulation infrared reflection–absorption spectroscopy as well as contact angle studies proved the formation of monolayers with varying surface chemistry. The wet-adhesion strength was tested by 90° peel tests after application of an epoxy-amine adhesive. Linear sweep voltammetry was performed to evaluate the corrosion inhibition of the monolayers, and the corrosion resistance of the metal/adhesive composite was investigated by means of its corrosive delamination behavior. The electrochemical measurements demonstrated that reducing the surface concentration of ADPA improved the corrosion inhibition of the monolayer. However, the corrosive delamination experiments revealed that the improved corrosion inhibition by the self-organized DPA is of minor importance for the corrosion behavior of the metal/adhesive composite, as the adhesive properties dominate.

Composite scaffold of electrospun nano-porous cellulose acetate membrane casted with chitosan for flexible solid-state sodium-ion batteries

Emerging as a safe and economically viable alternative to lithium-ion batteries, the solid-state sodium ion battery (ss-SIB) has captured increasing attention as a transformative technology for realizing a decarbonized economy and ensuring a sustainable energy supply. Here we report a nanoarchitecture strategy of biodegradable, biocompatible, and naturally abundant cellulose derivative (cellulose acetate, CA) and chitosan (CH) biopolymer-based nano-porous electrospun composite electrolyte (ECE) for flexible and wearable ss-SIBs. A simple combination of electrospinning and solution casting was utilized to fabricate mechanically robust (13.76 MPa), thin-film (0.067 mm), and highly flexible ECE. The ionic conductivity of ECE was enhanced through optimization, taking into account the amount of sodium salt (NaPF6). The resulting ECE exhibited a sodium-ion conductivity of 1.04 ×10−4 S·cm−1 and a sodium ion transference number of 0.48 at room temperature (RT=23 °C). The obtained Na+ transference number of 0.48 and a low activation energy (Ea = 0.13 eV) indicate the easy charge carrier diffusion ability of as-prepared ECE. The electrochemical stability window (ESW = 4.04 V) of ECE is studied by the linear sweep voltammetry (LSV) with the assembly of stainless steel and sodium metal electrodes. Without any interfacial modification, a uniform, stable, and long-time room temperature (RT) galvanostatic Na plating-stripping was observed for 1000 hrs at 0.5 mA·cm−2 current density in a symmetric (Na|ECE|Na) cell, this underscores impressive electrochemical stability and compatibility of ECE with sodium metal. Utilizing Na3V2(PO4)3 (NVP) as cathode, fabricated ECE, and Na metal as anode in a hybrid full cell, a notable RT specific discharge capacity of 98.1 mA·h·g−1 was attained at a rate of 0.1 C with a capacity retention of 93.4 % over 120 charge-discharge cycles. This highlights the practical applicability of the nanostructured electrospun composite electrolyte for flexible and wearable ss-SIBs.

Influence of Different Ions on Pulse Electrodeposition of CaCO3 Scales in the Simulated Seawater.

In the circulating water system of coastal power plants, various kinds of ions have a great influence on the formation and growth of CaCO3 scales. This paper focuses on investigating the influence of existing ions on the pulse electrodeposition behaviors of CaCO3 scales. Different concentrations of ions, such as Fe3+, Mg2+, PO43- and SiO32-, are introduced to simulate the actual seawater environment, and their influence on the CaCO3 scale deposition behaviors is assessed by linear sweep voltammetry, chronoamperometry, and electrochemical impedance spectroscopy tests. The surface coverage of the CaCO3 scale layer is evaluated through the residual current density and polarization resistance values, while the crystal structure and surface compactness of the layer are confirmed by the scanning electron microscope and X-ray diffractometer tests. Results indicate that high concentrations of Mg2+, Fe3+, and PO43- ions have the most significant inhibitory effect on the pulse electrodeposition of CaCO3 scales, among which the inhibition effect of Mg2+ ions is mainly reflected in the change of crystal morphology of CaCO3, that is, the crystallization growth process is inhibited. The inhibition effect of PO43- ions is mainly reflected in the gradually reduced coverage and density of CaCO3 crystals on the electrode surface, suggesting that the crystallization nucleation process is inhibited, while Fe3+ ions have a certain inhibition effect on both the crystallization nucleation and growth processes. Furthermore, lower concentrations of SiO32- ions also display a significant inhibition effect on the crystallization nucleation and growth process, and the inhibition effect weakens with increased concentration. This study provides a theoretical basis for exploring the removal of ions in the industrial water softening field.

Reduced Graphene Oxide Decorated Titanium Nitride Nanorod Array Electrodes for Electrochemical Applications

This work describes the fabrication and characterization of a new high surface area nanocomposite electrode containing reduced graphene oxide (rGO) and titanium nitride (TiN) for electrochemical applications. This approach involves electrochemically depositing rGO on a high surface area TiN nanorod array electrode to form a new nanocomposite electrode. The TiN nanorod array was first formed by the glancing angle deposition technique in a DC (Direct Current) sputtering system. GO flakes of ~1.5 μm in diameter, as confirmed by Dynamic Light Scattering (DLS), were electrodeposited on the nanostructured TiN electrode via the application of a fixed potential for one hour. The surface morphology of the as-prepared rGO/TiN electrode was evaluated by scanning electron microscopy (SEM) and the presence of rGO on TiN was confirmed by Raman Microscopy. The CV shows an increase in the capacitive current at rGO/TiN as compared to TiN. The rGO decorated TiN electrode was then used for analyzing the electrocatalytic oxidation of ascorbic acid and dopamine, and the reduction of nitrate by CV and linear sweep voltammetry (LSV), respectively. CV or LSV show that the electrochemical kinetics of these three analytes are significantly faster on rGO/TiN than TiN itself. Overall, the rGO/TiN electrode showed better electrochemical behavior for biomolecules like ascorbic acid and dopamine as well as another target analyte, nitrate ions, compared to TiN by itself.

Effects of different pretreatments on Ti/RuO2-TiO2 anode

In this study, H2C2O4, H2SO4, HNO3, and HCl were used to etch the TA2 titanium matrix at the same concentration and temperature, and the effects of different acid etching methods on the properties of the titanium matrix and Ru-Ti electrode were investigated. The surface morphology of the titanium substrate and anode after acid etching was observed by scanning electron microscopy (SEM), while the electrochemical performance of the anode was determined by cyclic voltammetry (CV), linear sweep voltammetry (LSV), and tafel plots. SEM observations showed that H2C2O4 had the best etching effect on the titanium substrate, as the scratches were uniform, and the surface cracks of the prepared anode reached 4–6 μm; Analysis of the CV curves revealed that the Ti/RuO2-TiO2 anode prepared by H2C2O4 etching had the highest surface charge capacity (172 mC) compared to the anodes prepared by other acid etchings, while the LSV curves showed that the Ti/RuO2-TiO2 anode after H2C2O4 etching had the lowest polarization potential (1.232 V). Tafel curve analysis revealed that the corrosion potential of the Ti anode prepared by H2C2O4 etching was 0.203 V, and the self-corrosion current density was −5.11 A cm−2, indicating that the corrosion resistance of the Ti anode prepared by H2C2O4 treatment is the weakest. X-ray photoelectron spectroscopy analysis showed that the electrode surface changed from Ru4+ to Ru3+ after corrosion, with the Ti2p spectra showing similar transition from Ti4+ to Ti3+.

Influence of iridium-tantalum interlayers on the properties of ruthenium-iridium-tin metal oxide anodes

The intermediate layer could not only delay the passivation of the titanium matrix and prolong the service life of the metal oxide anode but also directly affected the crystallization behavior and crystal structure of its surface catalytic layer, thus affecting the electrocatalytic activity of the anode. This paper’s thermal decomposition method prepared the ruthenium iridium tin metal oxide anodes with different layers of the iridium-tantalum interlayer. XRD and SEM were used to characterize the prepared electrode. Cyclic voltammetry, linear sweep voltammetry, accelerated life test et al were used to analyze the electrode performance. The results showed that the electrochemical roughness increased, the volt-ampere capacity increased, the charge transfer resistance decreased, and the electrocatalytic activity increased after adding the iridium-tantalum intermediate layer. The anode stability was greatly improved, and the accelerated life was prolonged. Among them, the greatest changes were observed when one iridium-tantalum interlayer was added, with the electrochemical roughness increasing from 283.33 % to 616.67 %, the volt-ampere charge increasing from 25.11 mC·cm−2 to 47.24 mC·cm−2, the charge transfer resistance decreasing from 1.754 Ω·cm2 to 0.684 Ω·cm2, and the enhanced electrolysis lifetime extending from 288 h to 504 h. Both the anode’s service life and electrocatalytic performance were greatly increased.

Physical vapour deposition fabrication of MoO3-based photoanode for water splitting to generate hydrogen.

MoO3 thin film was fabricated on an indium tin oxide substrate using the physical vapor deposition technique. X-ray diffraction and scanning electron microscopy study to investigate surface morphology, grain size, and surface structure, which are critical for absorbing solar spectra in water splitting for hydrogen energy generation. Ultraviolet-visible spectroscopy was used to confirm the absorption of solar spectra and the percentage of transmittance. Fourier-transform infrared analysis provided the functional groups present in the deposited thin film. The Tauc plot was used to determine the thin-film band gap, which allowed for the analysis of charge carrier transitions from the conduction band to the valence band. Electrochemical impedance spectroscopy investigations confirmed the charge transfer processes to the counter electrode and electrolyte interfaces. The observed low curve for MoO3 indicated low resistance and allowed efficient charge transfer. Linear sweep voltammetry analysis was used to measure photocurrent and solar light to hydrogen emission when the thin film was exposed to solar spectra. The thin film's observed hydrogen emission rate was 3731.74 mol g-1 h-1, and the STH% of MoO3 was found to be 0.345% at 0.8 V. These findings highlight the promising potential of MoO3 as a material for hydrogen energy generation using solar light.

Ion- and surface-sensitive interactions during oxygen evolution reaction in alkaline media

Abstract Clean and sustainable energy has turned towards electrochemical water splitting as a viable solution in minimizing carbon emissions. Electrolysis of water converts electrical energy to chemical energy, through the production of hydrogen and oxygen gases, which can be harnessed for potential applications without contributing to greenhouse emissions. While this energy storage process shows great potential, its efficiency is hindered by the sluggish kinetics of the oxygen evolution reaction (OER). As a result, its widespread application in green electrolytic technologies is limited hence investigations on improving OER kinetics are of utmost importance. Recent research breakthroughs indicate that alkali metal cations are more than passive observers. They play complex roles in the electric double layer (EDL), which positively influences the OER kinetics. The presence of numerous ions and their combinations presents a challenge of complexity. This study aims to delve into the impact of alkali metal cations on OER activity due to the variance in their hydration energies. Specific investigations focusing on different alkali metal cations in solution, such as Li+, Na+, and K+, was conducted on RuO2 to gain a deeper understanding of how these ions interact with both reactants and intermediate species in the reaction kinetics. Traditional electrochemical tests, including cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and accelerated degradation test (ADT) measurements were employed to elucidate critical aspects such as surface activation, electric double layer interactions, catalytic activity and stability, ohmic resistance, and mass and charge transport.

Nghiên cứu tính chất điện hóa, cấu trúc và khả năng xúc tác khử điện hóa oxygen của vật liệu Fe-Porphyrin trên bề mặt HOPG

This paper describes an efficient approach to fabricate Fe-Porphyrin thin film deposited on highly oriented pyrolytic graphite substrate (HOPG/FePP) via the dip-coating method serving as a novel electrocatalyst for oxygen reduction reaction (ORR) in acidic medium. The electrochemical, morphological behaviors and surface structure at the molecular level of the HOPG/FePP as well as its catalytic activities were characterized upon employing a state-of-the-art toolbox including cyclic voltammetry (CV), atomic force microscopy (AFM), electrochemical scanning tunneling microscopy (EC-STM) and linear sweep voltammetry (LSV). Consequently, the HOPG/ FePP thin film exhibited a significantly enhanced catalytic activity for ORR under applied experimental conditions.

Controllable synthesis of cross-linked 3D ZnO nanosheet toward a nitrite electrochemical sensor

A 3D cross-linked ZnO (cl-ZnO) nanosheets were prepared via a simple one-pot hydrothermal approach, and then characterized by a series of modern advanced technique including XRD, SEM, TEM and XPS. This nanomaterial was used to modify the glass carbon electrode (GCE), obtaining an electrochemical sensor (cl-ZnO/GCE) of which the electrochemical properties were studied using various electrochemical techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The sensor exhibited remarkably enhanced electrocatalytic activity for nitrite ions (NO2-) in comparison to that of the commercially available ZnO-modified GCE. Two electrochemical techniques, including chronoamperometry (CA) and linear sweep voltammetry (LSV) were adopted to test the determination performance of the sensor for nitrite, it exhibited a good linear relationship within the range of 0.8 μmol·L-1 - 0.462 mmol·L-1 and 0.608 - 7.84 mmol·L-1 evaluated by CA, the limit of detection (LOD) and sensitivity for NO2- were 0.26 μmol·L-1 (S/N = 3) and 824.6 µA (mmol·L-1)-1cm-2, respectively. For LSV, the two linearity responses of 0.95 μmol·L-1- 0.515 mmol·L-1 and 0.667 mmol·L-1- 5.41 mmol·L-1, high sensitivity of 1336.1 µA (mmol·L-1)-1cm-2 with low LOD of 0.32 μmol·L-1 were gained. This sensor can be employed to detect trace amount of NO2- in ham sausage and pickled vegetables successfully, supporting an insight and strategy for more sensitive nitrite electrochemical sensor.

Recovering the properties of aged bitumen using bio-rejuvenators derived from municipal wastes

Ageing of bitumen leads to significant performance deterioration of asphalt pavements and leads to material properties that are not conducive to recycling. Aiming to maximise the reusability of bitumen, this study investigated the feasibility of rejuvenating aged bitumen using bio-based rejuvenators synthesised from municipal wastes. Two bio-rejuvenators were used in this study, namely Rej-A which was a crude polymer with bio-waste pyrolysis dense fractions and Rej-B which was a filtered pyrolysis wax further derived from Rej-A. The bio-rejuvenators, virgin, aged, and rejuvenated bitumen were characterised using a comprehensive testing programme of gas chromatography and mass spectrometry (GC-MS), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), multiple stress creep and recovery (MSCR), linear amplitude sweep (LAS), and frequency sweep tests. It was observed that both bio-rejuvenators produced in this study can effectively recover the rheological properties of aged bitumen, improving its fatigue performance, e.g. the fatigue lives (at 15 % strain level) of Rej-A and Rej-B rejuvenated bitumen were 5.4 times and 3.0 times of that for aged bitumen when the dosage was 14 %. The rejuvenated bitumen was more sensitive to strain while less sensitive to temperature compared with virgin bitumen. Overall, Rej-A outperformed Rej-B in recovering the properties of aged bitumen. However, Rej-A was thermally unstable, undergoing 15.6 % mass loss when heated to 160 °C.

Antibiotic Degradation via Fenton Process Assisted by a 3-Electron Oxygen Reduction Reaction Pathway Catalyzed by Bio-Carbon-Manganese Composites.

Bio-carbon-manganese composites obtained from olive mill wastewater were successfully prepared using manganese acetate as the manganese source and olive wastewater as the carbon precursor. The samples were characterized chemically and texturally by N2 and CO2 adsorption at 77 K and 273 K, respectively, by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction. Electrochemical characterization was carried out by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The samples were evaluated in the electro-Fenton degradation of tetracycline in a typical three-electrode system under natural conditions of pH and temperature (6.5 and 25 °C). The results show that the catalysts have a high catalytic power capable of degrading tetracycline (about 70%) by a three-electron oxygen reduction pathway in which hydroxyl radicals are generated in situ, thus eliminating the need for two catalysts (ORR and Fenton).