Electrochemical Analysis Research Articles

Constructing a Polyoxometalate-Based Metal-Organic Framework for Photocatalytic Oxidation of Thioethers to Sulfoxides Utilizing In Situ-Generated Superoxide Radicals.

Developing new photocatalysts for the selective oxidation of thioethers to high-value-added sulfoxides under low-oxygen mild conditions is a promising but challenging strategy. Here, a new polyoxometalate-based metal-organic framework (POMOF), CoBW12-TPT, was successfully synthesized, wherein continuous π···π stacking interactions and direct coordination bonds not only strengthen the framework's stability but also accelerate electron transfer. A series of experiments and theoretical studies, including control experiments, kinetic studies, electrochemical spectroscopic analyses, and electron paramagnetic resonance, revealed the synergistic catalytic effect among Co(II) metal centers, BW12O405-, and the photosensitizer TPT. CoBW12-TPT was applied in the photocatalytic oxidation of thioethers to sulfoxides. Under irradiation, the photoinduced electron transfer of POMOF leads to the generation of superoxide radicals from O2, which controls the selective generation of sulfoxide compounds in the photocatalytic desulfurization reaction and shows good activity. In particular, it can be applied to the construction of some drug molecules such as Modafinil and Albendazole Oxide.

Enhancing Alkaline Hydrogen Evolution by Regulating H and OH Binding Strength through Strong Metal-Support Interactions.

Establishing optimized metal-support interaction (MSI) between active sites and the substrate is essential for modulating the adsorption properties of key reaction intermediates during catalysis, thereby enhancing the catalytic performance. In this study, catalyst composites with varying degrees of MSI are constructed using ruthenium (Ru) and different carbon nanotubes, and their performance for alkaline hydrogen evolution reaction (HER) is systematically investigated. Detailed kinetic assessments reveal that catalysts with a strong MSI exhibit superior HER activity. For instance, Ru-O-CNT catalyst composite demonstrates an encouragingly low overpotential of 11 mV at 10 mA cm-2 and excellent stability. Electrochemical voltammetry analysis indicates that an effective MSI optimizes the binding strength of both *H and *OH, accelerating the HER process. Furthermore, we showcase that an industrial-level electrolyzer, assembled using Ru-O-CNT as the cathodic catalyst, achieves impressive performance with a low cell voltage of 1.72 V and high stability at a current density of 1 A cm-2.

Enhancing the acidic oxygen evolution reaction efficiency of sol–gel synthesized SrCo0.5Ir0.5O3 catalysts through optimized ball milling and acid leaching

High-efficiency and low-cost catalysts for the oxygen evolution reaction (OER) in acidic electrolytes are critical for electrochemical water splitting in proton exchange membrane (PEM) electrolyzers to produce green hydrogen, a clean fuel for sustainable energy conversion and storage. Among OER catalysts, solid-state synthesized SrCo1−xIrxO3 has demonstrated superior activity compared to commercial standards, such as IrO2 and RuO2. However, the solid-state synthesis process is economically inefficient for industrial use due to the potential for impurities and low yield of the final product. In addition, the requirement for electrochemical cycling to activate the catalyst introduces contaminations and uncertainties for industrial applications. In this study, a modified solution-based sol–gel method was employed to produce SrCo0.5Ir0.5O3 (SCIO) with high purity and yield. Subsequent ball milling and acid leaching treatments were applied, resulting in a catalyst with higher efficiency than those activated solely by electrochemical cycling. The electrochemical analysis and physical characterizations of our SCIO catalyst after ex-situ post-synthesis treatments show a similar active phase in composition and structure to those obtained through in situ electrochemical cycling and activation. Our approach simplifies the preparation process, making the catalyst ready for direct use in PEM electrolyzers without further treatment, offering a promising solution for producing high-performance, industrial-scale OER catalysts.

Unlocking the Photoluminescence and Photostability of Au11 Clusters through Pt-Mediated Band-Gap Engineering.

Au nanoclusters often demonstrate useful optical properties such as visible/near-infrared photoluminescence in addition to remarkable thermodynamic stability owing to their superatomic behavior. The smallest of the 8e- superatomic Au nanoclusters, Au11, has limited applications due to its lack of luminescence and relatively low stability. In this work, we investigate the introduction of a single Pt dopant to the center of a halide- and triphenylphosphine-ligated Au11 nanocluster, obtaining a cluster with a proposed molecular formula PtAu10(PPh3)7Br3. Electrochemical and spectroscopic analysis reveal an expansion of the HOMO-LUMO gap due to the Pt dopant, as well as relatively strong near-infrared (NIR) photoluminescence which is atypical for an M11 cluster (λmax = 700 nm, Φ = 1.88%). The Pt dopant additionally boosted photostability more than tenfold. Lastly, we demonstrate the application of the PtAu10 cluster's NIR photoluminescence in the detection of the nitroaromatic compound 2,4-dinitrotoluene, with a limit-of-detection of 9.52 μM (1.74 ppm). The notable ability of a single central Pt dopant to unlock photoluminescence in a non-luminescent nanocluster highlights the advantages of heterometal doping in the tuning of both the optical and thermodynamic properties of Au nanoclusters.

Electrochemical Detection of Hydrogen Peroxide at High Concentrations Using Hastelloy G35 Electrode.

The detection of hydrogen peroxide (H2O2) at elevated concentrations while eliminating oxygen interference presents a significant challenge. Nickel-based stainless steel, such as Hastelloy G35, has shown excellent corrosion resistance. However, it has never been used in electroanalysis. In this study, the electrochemical analysis of H2O2 was conducted for the first time using nickel-based stainless steel electrode. The Hastelloy G35 electrode exhibited a very wide linear range from 1 up to 1000 mM and a detection limit of 0.0135 mM. The method is free from interference by oxygen. This method effectively detected H2O2 in skin wound wash solutions with excellent recoveries. The excellent performance of this method enhances its applicability in various fields, including industrial processes, environmental monitoring, and analytical chemistry, where quantifying concentrated H2O2 is of utmost importance. It shows that nickel-based stainless steel is promising for electroanalysis.

Clinically Deployable Electro-Immunosensing Device Comprising Bioactive Glass-MWCNT for Alkaline Phosphatase Detection in Human Serum Samples.

Bone is a dynamic tissue that serves several purposes in the human body, including storing calcium, forming blood cells, and protecting and supporting the body's organs. Alkaline phosphatase (ALP) is secreted into the circulation by osteoblasts, the cells responsible for making bone. It attaches to the surface of osteoblast cells or matrix vesicles. Accordingly, ALP is present in serum and is a popular biomarker for the evaluation of bone disease and other disorders in clinical evaluations. In this study, a composite probe made of bioactive glass (BG) and multiwalled carbon nanotubes (MWCNT) was used to detect ALP through electrochemical impedance spectroscopy (EIS) without the need for labels. By combination of physical methods with electrochemical analysis, the biosensor probe was characterized. The analytical performance of the biosensor was evaluated using EIS, and the results revealed that it has a limit of detection (LOD) of 2.29 ± 0.35 U/L and a linear dynamic range (LDR) of 25-600 U/L; both of which are within the acceptable range for ALP detection in clinics. When tested against serum interfering chemicals, the biosensor probe that was designed shows a strong selectivity for ALP (Ksel < 0.06). In addition, human serum and fetal bovine serum were used to test the system's ability to detect ALP in biological samples.

Controlled Structural Activation of Iridium Single Atom Catalyst for High-Performance Proton Exchange Membrane Water Electrolysis.

Iridium single atom catalysts are promising oxygen evolution reaction (OER) electrocatalysts for proton exchange membrane water electrolysis (PEMWE), as they can reduce the reliance on costly Ir in the OER catalysts. However, their practical application is hindered by their limited stability during PEMWE operation. Herein, we report on the activation of Ir-doped CoMn2O4 in acidic electrolyte that leads to enhanced activity and stability in acidic OER for long-term PEMWE operation. In-depth material characterization combined with electrochemical analysis and theoretical calculations reveal that activating Ir-doped CoMn2O4 induces controlled restructuring of Ir single atoms to IrOx nanoclusters, resulting in an optimized Ir configuration with outstanding mass activity of 3562 A gIr-1 at 1.53 V (vs RHE) and enhanced OER stability. The PEMWE using activated Ir-doped CoMn2O4 exhibited a stable operation for >1000 h at 250 mA cm-2 with a low degradation rate of 0.013 mV h-1, demonstrating its practical applicability. Furthermore, it remained stable for more than 400 h at a high current density of 1000 mA cm-2, demonstrating long-term durability under practical operation conditions.

Unraveling Serial Degradation Pathways of Supported Catalysts through Reliable Electrochemical Liquid-Cell TEM Analysis.

Electrochemical liquid-cell transmission electron microscopy (e-LCTEM) offers great potential for investigating the structural dynamics of nanomaterials during electrochemical reactions. However, challenges arise from the difficulty in achieving the optimal electrolyte thickness, leading to inconsistent electrochemical responses and limited spatial resolution. In this study, we present advanced e-LCTEM techniques tailored for tracking Pt/C degradation under electrochemical polarization at short intervals with high spatial resolution. Our innovative approach combines microfabrication-based sample preparation with in situ control of electrolyte thickness, ensuring reliable electrochemical signal acquisition and direct observation of sequential catalyst degradation. Quantitative imaging analyses conducted at both global areas and single-particle levels unveil a distinctive degradation mechanism primarily driven by nanoparticle migrations. Smaller nanoparticles exhibit a higher susceptibility to migration, leading to coalescence and final detachment in series. This migration-gated degradation mechanism provides a new perspective on the size-dependent durability of supported nanoparticles, complementing the prevailing explanation centered on the size-dependent dissolution kinetics of nanoparticles.

Exploiting the Electrostatic Binding of Ruthenium Hexamine Molecular Redox Nanowires onto DNA/OGCN Biohybrid Electrodes toward the Electrochemical Detection of COVID-19.

The Coronavirus Disease 2019 (COVID-19) recently emerged as a life-threatening global pandemic that has ravaged millions of lives. The affected patients are known to frequently register numerous comorbidities induced by COVID-19 such as diabetes, asthma, cardiac arrest, hypertension, and neurodegenerative diseases, to name a few. The expensiveness and probability of false negative results of conventional screening tests often delay timely diagnosis and treatment. In such cases, the deployment of a suitable biosensing platform can readily expedite the rapid diagnosis process for enhanced patient outcomes. We report the development of an electrochemical genosensor based on DNA/OGCN (DNA/oxygenated graphitic carbon nitride) nanohybrids for the quantification of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) DNA─the key biomarker for COVID-19. This is achieved by exploiting the molecular nanowire-formation capability of the [Ru(NH3)6]2+/3+ redox probe onto the DNA phosphate backbone via electrostatic interactions. The microstructural characterization of OGCN was performed using scanning electron microscopy (SEM) coupled with an energy-dispersive X-ray (EDX) module, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy. The electrochemical analyses were performed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), while the analytical performance of the sensor was evaluated using square wave voltammetry (SWV). The developed sensor exhibited a wide linear detection range within 10 fM-10 μM, with a limit of detection (LoD) of ∼7.23 fM with a high degree of selectivity toward SARS-CoV-2 target DNA, thereby indicating its potential to be employed in a point-of-care scenario toward providing affordable healthcare to the global populace.

Synergistic effect in liquid metal heartbeat with high‐efficiency energy conversion

AbstractThe phenomenon of liquid metal “heartbeat” oscillation presents intriguing applications in microfluidic devices, drug delivery, and miniature robotics. However, achieving high vibrational kinetic energy outputs in these systems remains challenging. In this study, we developed a graphite ring electrode with V‐shaped inner wall that enables wide‐ranging control over the oscillation performance based on droplet size and the height of the V‐shape. The mechanism driving the heartbeat is defined as a dynamic process involving the transformation of the oxide layer. Through electrochemical analysis, we confirmed three distinct states of the heartbeat and introduced a novel model to elucidate the role of the V‐shaped structure in initiating and halting the oscillations. A comprehensive series of experiments explored how various factors, such as droplet volume, voltage, tilt angle, and V‐shape height, affect heartbeat performance, achieving a significant conversion from surface energy to vibrational kinetic energy as high as 4732 J m−2 s−1. The increase in energy output is attributed to the synergistic effect of the V‐shape height and droplet size on the oscillations. These results not only advance our understanding of liquid metal droplet manipulation but also pave the way for designing high‐speed microfluidic pumping systems.

Development of nitrogen and phosphorus dual-doped reduced graphene oxide from waste plastic for supercapacitor applications: Comparative electrochemical performance in different electrolytes

The persistent non-biodegradable nature of plastic highlights the urgent need for effective waste management and resource conservation, underscoring the crucial importance of recycling and upcycling within a cradle-to-cradle framework. This research introduces an eco-friendly and straightforward upcycling process for plastic waste, which produces significant quantities of reduced graphene oxide through a carefully designed 2-stage pyrolysis method. To enhance the electrochemical properties of the reduced graphene oxide, they were doped with heteroatoms (i.e. nitrogen and phosphorus) via a hydrothermal route. Also, as the nature of the electrolyte plays a significant role in electrochemical analysis, a comparative evaluation of the supercapacitive performance of the heteroatom-doped reduced graphene oxide was conducted across various aqueous electrolytes, including 1 M H2SO4, 6 M KOH, and 2 M KCl, as well as hydrogel polymer electrolytes such as 1 M H2SO4/1 M PVA, 2 M KCl/1 M PVA, and 6 M KOH/1 M PVA. Our results demonstrate that synthesized material from waste plastic exhibits excellent performance, particularly when combined with a 1 M H2SO4 electrolyte, achieving the highest specific capacitance of 407.6 F/g. In conclusion, this study presents a cost-effective and sustainable approach to promoting a circular economy by repurposing waste plastic for energy storage applications.

Concentration-dependent kinetic study of graphene oxide (GO) reduction using biophenol and electrochemical analysis

Renewable biophenol gallic acid (GA) is a safer, non-toxic, and efficient alternative to hydrazine for producing reduced graphene oxide (rGO), which exhibits excellent electrochemical properties and supports sustainable energy applications.

The deep investigation of structural and electrochemical analysis on the anti-corrosion behavior of MgCo2O4 and ZnCo2O4 spinel nanoparticles in acid medium

The deep investigation of structural and electrochemical analysis on the anti-corrosion behavior of MgCo2O4 and ZnCo2O4 spinel nanoparticles in acid medium

Electrodeposition of Cu nanowires with ultrahigh-density twin boundaries: an electrochemical perspective on nanotwinning.

Many spectacular nanotwinned Cu (nt-Cu) properties depend on the spacing of adjacent twin boundaries (TBs) inside crystal grains. The average TB spacing is typically 10-100 nm in electrodeposited nt-Cu films. This study employed template-assisted electrodeposition to grow nt-Cu nanowires with high-density TBs (average TB spacing <5 nm). The effects of Cu seed annealing and template pore size on TB spacing were systematically investigated through microstructural characterization and electrochemical analysis. A model based on the stress accumulation level and electrochemical parameters was proposed to assess the twinning criteria during the electrodeposition of nt-Cu nanowires. This research provides mechanistic insights into the nanotwinning process and highlights the potential for the control of twin structures in nanomaterials.

EFEITO DAS DOSES DE DEJETO LÍQUIDO DE SUÍNOS NOS ATRIBUTOS FÍSICOS, QUÍMICOS E ELETROQUÍMICOS EM UM LATOSSOLO DO CERRADO

EFFECT OF LIQUID SWINE WASTEWATER DOSES ON PHYSICAL, CHEMICAL AND ELECTROCHEMICAL ATTRIBUTES IN A CERRADO OXISOL. The addition of organic residues enhances soil and plant organic matter and nutrient content. To gauge the impact of varying liquid swine waste (LSW) levels on soil, we studied changes in a clayey Oxisol’s physical, chemical, and electrochemical traits from the Cerrado. LSW doses (0, 50, 150, 450, 600 m3 ha-1) were applied to the 0-0.20 m layer in a randomized design with three replicates. Post a 30-day incubation at 60% field capacity, the soil underwent mineralogical, physical (clay dispersed in water - CDW), chemical (sodium adsorption ratio - SAR, cation exchange capacity - CEC, base saturation - V%), and electrochemical (pH in H2O and KCl, ∆pH, point of zero charge - PZC, point of zero salt effect - PZSE, surface electric potential - ψo, and electrical conductivity - EC) analyses. The levels of exchangeable Ca, K, Mg, Na, and available P increased with increasing LSW doses. Increasing LSW doses in the soil led to an increase in EC, but soil salinization was not observed at the highest dose. With the application of LSW doses, there was a decrease in pH, ∆pH, PZSE, and an increase in CEC, PZC and ψo. Despite the increase in ψo, low clay dispersibility was observed.

Unraveling the corrosion inhibition mechanisms of Algerian Dryopteris filix mas leaf extract on A210C carbon steel in 1 M HCl: Comprehensive insights from electrochemical, morphological, XPS, and theoretical analyses

Unraveling the corrosion inhibition mechanisms of Algerian Dryopteris filix mas leaf extract on A210C carbon steel in 1 M HCl: Comprehensive insights from electrochemical, morphological, XPS, and theoretical analyses

Exploring Mg-Sn Alloys as Electrocatalysts for CO2 Electroreduction

Tin is one of the most selective electrocatalysts for CO2 reduction (CO2RR), mostly thanks to its poor activity towards the hydrogen evolution reaction (HER). Still, Sn electrodes are limited by their very high overpotential. We decided to investigate the electrochemical CO2RR catalytic activity of tin-magnesium alloys that can be easily obtained by thermal annealing from the elemental metallic powders. We found that the alloys exhibit a slightly improved activity in activity and selectivity towards CO2RR with formate as dominant product according to electrochemical and chemical analysis. Post-mortem characterization confirmed that this effect is not due to the alloys performance, but to Sn re-structuration. Most of the Mg is leached from the alloy into the electrolyte during CO2RR, leaving a highly porous Sn structure. These changes in morphology and surface area as triggered by Mg leaching, appear to be at the origin of the enhanced electrocatalytic performance.

BODIPYs as Fluorogenic Probes for Live-cell Imaging of Lipid Droplets: Photophysical and Computational Studies

Introduction: Lipid droplets (LDs) serve as primary storage sites for neutral lipids within cells and are crucial for lipid metabolism. Disorders affecting LDs can contribute to the pathogenesis of common metabolic diseases such as obesity and cancer, highlighting the importance of comprehend-ing LD biology in health and disease contexts. Background: Fluorescence assays are commonly used for the detection and quantification of lipids in bio-logical samples or lipid-rich environments. In this study, BODIPYs were synthesized and analyzed for structural confirmation. These compounds were subsequently evaluated for photophysical, electro-chemical (cyclic voltammetry) and theoretical analysis, followed by live-cell imaging studies to con-firm their affinity for intracellular lipid droplets. Results: BODIPYs have been identified as fluorogenic probes for live-cell imaging studies and found to serve as efficient and selective fluorescent substances for intracellular lipid droplets. Conclusion: These BODIPYs, especially 2b, are valuable addition to the expanding toolkit for intra-cellular diagnostics, offering versatility and reliability across various cellular imaging applications.

Bioelectronic and photogenerated electron synergistic catalyzed removal of chlorhexidine: Degradation and mechanism.

The extensive use of the antimicrobial compound chlorhexidine (CHD) has emerged as a significant threat to both the ecological environment and human health. To address this concern, a photo-electrochemical cell-microbial fuel cell (PMFC) system was studied for CHD removal by incorporating, for the first time, the photocatalysts black phosphorus/carbon nitride (BPCN) and Cu2O into the bioanode and air cathode of an MFC, respectively. By combining electrochemical, macro-genomic, and intermediate product analyses, the underlying mechanisms of bioelectronic and photoelectronic synergies were elucidated. Specifically, the bioanode and the energy band difference between BPCN and Cu2O accelerated the bioelectronic and photoelectronic transfer, reduced the reaction barrier, and enhanced the cathodic dechlorination pathway. Consequently, the PMFC showed a 31.4-fold and 8.0-fold increase in CHD removal rate compared to the MFC and PEC, respectively. The photogenerated electrons, on the other hand, acted as key cofactors, replacing cytochrome c and facilitating electron transfer at the microbial-electrode interface, which improved the system's energy yield by 53.9 %. Additionally, illumination selectively enhanced the abundance of anode functional species, carbon metabolism, and interspecific cooperation, resulting in a 4.03-fold increase in the removal of CHD and its intermediates. These findings offer new perspectives on biochemically sustainable environmental remediation for recalcitrant pollutants.

Corrosion Behaviour of Cu-Plate Current Collector under Ex-situ Cyclic Stability Testing for Energy Storage Application

This study compares the corrosion behaviour of a copper plate current collector subjected to an ex-situ cyclic stability test in a 6M KOH and a 6M Na2SO4 electrolyte solution for an electrochemical supercapacitor cell. Through experimental analysis, the change in microstructures resulting from the corrosion behaviour of the copper plate current collector samples are examined by employing various analytical techniques, including microscopy, spectroscopy, and surface roughness analyzer. The corrosion behaviour was studied by employing potentiodynamic polarization and electrochemical impedance spectroscopy analyses. The copper plate current collector samples analysed in 6M KOH and 6M Na2SO4 electrolyte solution showed uniform and localized corrosion product formation, respectively. The CU-72HRS sample recorded a corrosion potential of -608.6mV, -628.87mV, and -89.5mV, -87.588mV using both Tafel and resistance polarization data fitting analysis, respectively, for both 6M KOH and 6M Na2SO4 electrolyte solution using a scan rate of 5mV/s at a voltage window of -1 to 1V. Comparing the microstructural changes under various cyclic conditions provides valuable insights into the durability and reliability of copper plates as current collectors in energy storage systems. The results of this study help improve our understanding of the supercapacitor cell performance in ex-situ cyclic stability tests, assisting in the development of more efficient and durable energy storage technologies.