Electrochemical Methods Research Articles

Primer exchange reaction assisted CRISPR/Cas9 cleavage for detection of dual microRNAs with electrochemistry method.

Anelectrochemical sensor assisted by primer exchange reaction (PER) and CRISPR/Cas9 system (PER-CRISPR/Cas9-E) was established for the sensitive detection of dual microRNAs (miRNAs). Two PER hairpin (HP) were designed to produce a lot of extended PER products, which could hybridize with two kinds of hairpin probes modified on the electrode and initiate the cleavage of two CRISPR/Cas9 systems guided by single guide RNAs (sgRNAs) with different recognition sequences. The decrease of the two electrochemical redox signals indicated the presence of dual-target miRNAs. With the robustness and high specificity of PER amplification and CRISPR/Cas9 cleavage system, simultaneous detection of two targets was achieved and the detection limits for miRNA-21 and miRNA-155 were 0.43 fM and 0.12 fM, respectively. The developed biosensor has the advantages of low cost, easy operation, and in-situ detection, providing a promising platform for point-of-care detection of multiple miRNAs.

Electrochemical Label-free Methods for Ultrasensitive Multiplex Protein Profiling of Infectious Diseases.

Electrochemical detection methods are the more appropriate detection methods when it comes to the sensitive and specific determination of biomarkers. Biomarkers are the biological targets for disease diagnosis and monitoring. This review focuses on recent advances in label-free detection of biomarkers for infectious disease diagnosis. The current state of the art for rapid detection of infectious diseases and their clinical applications and challenges were discussed. Label-free electroanalytical methods are probably the most promising means to achieve this. We are currently in the early stages of the emerging technology of using label-free electrochemistry of proteins to develop biosensors. To date, antibody-based biosensors have been intensively developed, although many improvements in reproducibility and sensitivity are still needed. Moreover, there is no doubt that a growing number of aptamers and hopefully label-free biosensors based on nanomaterials will soon be used for disease diagnosis and therapy monitoring. And also here in this review article, we have discussed recent developments in the diagnosis of bacterial and viral infections, as well as the current status of the use of label-free electrochemical methods for monitoring inflammatory diseases.

Electrochemical remediation of methyl orange over reusable biochar ferrite coated photocatalytic plates

Biochar (BC) obtained from biomass pyrolysis holds immense potential for environmental remediation. The efficiency of BC can further be enhanced by incorporating metal nanoparticles (NPs) in the porous carbon matrix. In the present work nanocomposites (NCs) were prepared by the addition of ferrite nanoparticles (FNPs) into an oxidized BC matrix to create BC /Fe3O4 (BCF). This process improves BC stability, electron transfer, conductivity, and photocatalytic ability for dye degradation. Microstructure and functional group analysis of BCF was performed by SEM, XRD, and FTIR showing intercalation of FNPs with surface functionalities of oxidized BC matrix. The B-H curve of FNPs and BCF reveals super paramagnetic behavior with saturation magnetization (Ms, emu/g) of 67.36 and 20.01 respectively. BET surface area analysis shows surface area (m2/gm) 45.81 and 44.19 for oxidized BC and BCF respectively, that attributed to partial blocking of porous carbon matrix by FNPs. UV-DRS supports the semiconducting behavior of BCF with a significantly reduced band gap (eV) of 2.95 over pristine BC (4.76). BCF-coated photocatalytic plates (PCPs) were developed and utilized for the remediation of methyl orange (MeO) in water samples. Degradation of MeO was investigated over time by electrochemical methods. The square wave voltammetric method showed the limit of detection and quantification of 0.09 ppm and 0.28 ppm respectively for MeO over a glassy carbon electrode in 0.1 M acetate buffer. BCF-derived PCPs rendered ∼99 % degradation efficiency against MeO (50 mgL−1) under UV radiation over 240 min. Developed PCPs demonstrate reusability up to 5 cycles without any further purification step and offer efficient degradation of MeO making them suitable for the treatment of water polluted with dyes.

Hydrothermal Synthesis of Rare-earth Ferrate for Electrochemical Detection of 4-Aminophenol in Food Samples and Products

4-Aminophenol (4-APL/4-AP) is one of the toxic chemicals in the water sources. The electrochemical oxidation of 4-APL reaction was studied by electrochemical method with SPCE modified with perovskite rare-Earth ferrate (PrFeO3). The nanomaterials were characterize using various morphological analysis by TEM, XRD, FTIR, Raman, XPS. PrFeO3 needles modified SPCE demonstrated excellent electrocatalytic performance towards the electrooxidation of 4-APL under pH 7.0, having anodic peak current significantly higher than those of the bare SPCE. Using CV and amperometry method to analyse the sensor performance toward 4-APL detection. In CV, the synthetic sensor plays wide 4-APL detection range from 100–500 μM. In amperometry method, the sensor plays wide range of 4-APL detection from 0.03 to 1859 μM and the limit of detection is 0.014 μM. Mainly the proposed sensor material of PrFeO3/SPCE exhibit an excellent 4-APL detection carrying out in various food samples. Furthermore, regarding 4-APL analysis, PrFeO3/SPCE demonstrate outstanding selectivity, low limit of detection, repeatability, reproducibility, and operational stability.

Aptasensor based on gold nanostructure-decorated 2D Cu metal-organic framework nanosheets for highly sensitive and specific electrochemical lipopolysaccharide detection.

Detecting lipopolysaccharide (LPS) using electrochemical methods is significant because of theirexceptional sensitivity, simplicity, and user-friendliness. Two-dimensional metal-organic framework (2D-MOF) that merges the benefits of MOF and 2D nanostructure has exhibited remarkable performance in constructing electrochemical sensors, notably surpassing traditional 3D-MOFs. In this study, Cu[tetrakis(4-carboxylphenyl)porphyrin] (Cu-TCPP) and Cu(tetrahydroxyquinone) (Cu-THQ) 2D nanosheets were synthesized and applied on a glassy carbon electrode (GCE). The 2D-MOF nanosheets, which serve as supporting layers, exhibit improved electron transfer and electronic conductivity characteristics. Subsequently, the modified electrode was subjected to electrodeposition with Au nanostructures, resulting in the formation of Au/Cu-TCPP/GCE and Au/Cu-THQ/GCE. Notably, the Au/Cu-THQ/GCE demonstrated superior electrochemical activity because of the 2D morphology, redox ligand, dense Cu sites, and improved deposition of flower-like Au nanostructure based on Cu-THQ. The electron transfer specific surface area was increased by the improved deposition of Au nanostructures, which facilitates enriched binding of LPS aptamer and significantly improved thedetection performance of Apt/Au/Cu-THQ/GCE electrochemical aptasensor. The limit of detection for LPS reached 0.15fg/mL with a linear range of 1fg/mL - 100pg/mL. Theproposed aptasensor demonstrated the ability to detect LPS in serum samples with satisfactory accuracy, indicating significant potential for clinical diagnosis.

New triglycidyl ether triazine as a protective agent for metal: Comprehensive analysis

This study presents the synthesis and characterization of triglycidyl ether triazine (TGET), a novel epoxy resin, designed as a defensive agent for mild steel (C38) in a 1 M HCl environment. The corrosion inhibitory effectiveness of TGET was evaluated by various electrochemical methods and corroborated by surface analysis using surface and theoretical methods. The key findings demonstrate that the protection behavior of TGET rises with its concentration, achieving a maximum of 94.77% at 10-3 mol/L, indicating a highly effective reduction in iron dissolution. Surface analysis confirmed the establishment of a defensive cover on the metal surface. The theoretical studies supported the experimental data, suggesting a strong adsorption of TGET molecules on the steel surface through chemical interaction, primarily via electron donation from the N and O atoms of the TGET to the metal surface. These results establish TGET as a highly effective corrosion inhibitor with potential applications in protecting steel structures in industrial environments characterized by acidic conditions.

Theoretical and practical aspects of the mathematical description electrochemical purification of oil-contaminated soil

Abstract The electrochemical method is one of the most promising solutions for oil-contaminated soil remediation by passing small constant electric currents. The creation of installations for the electrochemical treatment of oil-contaminated soils requires an understanding of the ongoing processes, which can be achieved by developing a mathematical model. In this paper, we consider obtaining a mathematical description of the change of the oil pollution concentration from the time of direct current treatment and the distance to the electrodes, followed by experimental verification of the adequacy of the models to real electrochemical processes in oil-contaminated soils. The article shows the main approaches and stages of obtaining mathematical models for assessing the cleaning effectiveness. Mathematical models of pollutant concentration changes of the depending on the time and distance to the electrodes were obtained. A correlation between the most important design parameters of the installation and the parameters of the electrochemical process has been established. The resulting models can be used to design installations for electrochemical treatment of oil-contaminated soils.

Magnetic field-assisted electrochemical additive manufacturing of nickel structure: Growth mechanism and microstructural evolution

The microstructure and crystal texture of magnetically assisted electrochemical additive manufacturing parts play crucial roles in their mechanical properties and applications. This paper elucidates the electrocrystallization process of electrochemical additive manufacturing by constructing a magnetically assisted setup and exploring both nucleation mechanisms and growth kinetics. The electrochemical behavior of the system was analyzed using electrochemical methods under different magnetic field strengths. Nickel structures with aspect ratios of 7.0 and 8.2 were fabricated using the experimental setup, and their morphology, crystal texture, and microstructure were characterized. The results showed that without applying a magnetic field, the nucleation mechanism followed three-dimensional instantaneous nucleation under diffusion control. Under magnetic field conditions, forced convection, double layer charging, and hydrogen evolution reactions were combined to modify the S-H nucleation model, demonstrating that the magnetic field can significantly enhance the nucleation rate and number of nuclei. The initial growth of the microstructure did not exhibit preferential solid orientation, primarily forming refined equiaxed grains. Subsequently, a characteristic pentagonal structure developed, followed by spiral dislocation growth, with a significant transformation of equiaxed grains into columnar crystals. The crystal orientation eventually evolved to <110>, with many twin boundaries, among which Σ3 grain boundaries accounted for more than 55 %. Applying a magnetic field improved processing efficiency, altered the morphology and texture of the material, refined the grains, and increased the types of twins. These results provide theoretical and experimental support for electrochemical additive manufacturing.

Construction of chromium-free passivation film of pomelo peel extract on the surface of lithium-ion battery copper foil and study on anti-corrosion mechanism

Passivation treatment is the last key process to ensure the service life of copper foil for lithium-ion batteries. Although chromic anhydride commonly used in industry has an efficient passivation effect, it can threat human health and the environment. Herein, an environmentally friendly passivator is prepared from pomelo peel by a simple and economical solution extraction method, which makes copper foil have good anti-corrosion properties in air, chlorine-containing solution, and organic electrolyte. Electrochemical methods and X-ray photoelectron spectroscopy (XPS) confirm the potential of pomelo peel extractant (PP) to replace chromic anhydride as a passivating agent for copper foil. The interaction mechanism between PP and copper foil is analyzed by adsorption modeling, and the efficient passivation behavior of PP for copper foil is consistent with the Langmuir model. Density Functional Theory (DFT) calculations of the naringin (main component of PP) is performed to further reveal the protection mechanism of PP on copper foil. In addition, the copper foil treated by PP still has excellent electrochemical performance as lithium-ion battery current collector, indicating that the presence of PP not only protects the copper foil from corrosion, but also does not affect the conductivity of the copper foil. This research provides a new insight into the chrome-free passivation of copper foils, which is in line with the development concept of green production.

Surface State Modulation via Electrochemical Heterogeneous Redox Reactions for Full-Color Emission Carbon Dots.

Carbon dots (CDs) still suffer from unclear surface state fluorescence mechanism for fine modulation. Here, redox reactions for cathode and anode within electrochemical method are firstly employed to construct differentiated strategy for surface-state modulation, so as to obtain CDs with controllable emission in separated electrodes simultaneously. The fluorescence peaks of CDs from blue to red centered at 425 nm (mCDs-), 530 nm (mCDs+), 580 nm (oCDs-) and 665 nm (oCDs+) are mainly originated from the different bombardment effects of the ions and reaction tendencies of modifier during the electrolysis process. The phenylenediamine (as modifier) tends to introduce the amino groups on the surface of CDs- while introduced nitrogen atoms into the carbon nucleus skeleton around the anode, thus leading to much larger size and the formation of the graphite N for CDs+. It is the different surface states formed by phenylenediamine and the absorption redshift triggered by graphite N that ensures the tunable emission. The improved electrochemical method is of great significance for finely spectra modulation and efficient synthesis.

IMPACT: Innovative (nano)Materials and processes for advanced catalytic technologies to degrade PFOA in water

We hereby report the development of a novel electrochemical method to degrade perfluorooctanoic acid (C7F15COOH, PFOA). At the center of the approach are bimetallic Pd–Ru nano-catalyst materials called IMPACT: Innovative (nano)Materials and Processes for Advanced Catalytic Technologies. IMPACT uses flavonoid-sequestered Pd–Ru, allowing the development of specialized electrodes with tunable properties to sequentially degrade PFOA in wastewater samples into a sustainable byproduct via an indirect electrochemical method. Electron transfers at RuOxHy species stabilize the Pd component of the nano-catalysts, enabling the degradation process via PFOA deprotonation, chain shortening, decarboxylation, hydrolysis, fluoride elimination, and CF2 flake-off mechanism. IMPACT enabled the observation of redox peaks at −0.26 V and 0.56 V for the first time, with accompanying reduction peaks at −0.5V and 0.29 V, respectively. These redox peaks, which correlated with the concentrations of PFOA (20, 50, 100, 200, and 400.mg L−1), were verified and confirmed using electrochemical simulations. Control experiments did not show degradation of PFOA in the absence of Pd–Ru nano-catalyst. The degradation in wastewater was obtained within 3 h with an efficiency of 98.5%. The electrochemical degradation products of PFOA were identified using High-resolution desalting paper spray mass spectrometry (DPS-MS) and collision-induced dissociation (CID) analysis. The results yielded C2F5COOH, C3F7COOH, and C6F13OH with dissociation losses of CF2O or CO2. IMPACT introduces a novel nano-catalyst with high efficiency and a reliable capability that defluorinates strong C–F bonds that are components of recalcitrant organics in myriad environmental matrices.

Study of initial corrosion and protection behavior of bronze from the Western Zhou Dynasty assisted by BTA

Electrochemistry methods and surface characteristics were used to investigate the corrosion behaviors in the initial stage and the inhibition efficiency of BTA in simulated soil environments for simulated bronze samples. The results show that the inhibition efficiency can reach 99.96%; A protrusion morphology of corrosion products formed by PbSO4 with a channel formed by Cu compounds that can transport corrosive media was found in the cross-section of the Pb-rich samples. A mechanism for galvanic corrosion was proposed with the assistance of the inhibition effect of BTA, which can explain the different corrosion behaviors of samples with different Pb contents.

Microhardness and energy dispersive X-ray evaluation of dentinal walls following chemical and electrochemical dissolution of fractured nickel-titanium file: An in vitro study

PurposeChemical dissolution of nickel-titanium (NiTi) files involves the application of a fluoride solution in direct contact with a damaged instrument, whereas electrochemical dissolution involves the application of an electrical current to the electrolyte, which accelerates fragment dissolution. This study aimed to determine the hardness and concentration of calcium and phosphorus (Ca and P) ions in dentinal walls following chemical and electrochemical dissolution of fractured ProTaper F2 files with a novel chemical solution.Materials & Methods: Thirty human maxillary first molar palatal roots with fractured ProTaper F2 files in the middle third (length, 2.5 mm were divided into three groups according to the treatment techniques used with a novel solution (NaF 12 g/L + NaCl2 60 g/L + MgCl2 60 g/L + CaCl2 60 g/L) at pH 5: Group 1: distilled water (control group), Group 2: electrochemical dissolution, and Group 3: chemical dissolution using the novel solution. The novel solution was placed for 10 min using an electrochemical technique, and for 30 min in contact with the separated instrument in the chemical group. The Vickers microhardness test was performed in three areas: at 3, 6, and 9 mm from the apex, and an energy-dispersive X-ray test for both Ca and P ions was performed. The analysis of variance (ANOVA) and Tukey's tests were used for statistical analysis. ResultsAccording to the one-way ANOVA analysis, no difference was observed between the tested approaches (P > 0.05) in the three areas evaluated (3, 6, and 9 mm), with no difference in the Ca/P ratio between the tested groups. ConclusionCompared to the control group, the use of chemical and electrochemical dissolution methods with the novel solution did not affect dentin hardness or dentinal structure in terms of the Ca/P ratio, thereby indicating promising results while saving time.

A Highly Sensitive and Rapid Enzyme Biosensor Based on AuNPs/CS@cMWCNTS for Detecting Fusarium Acid

Fusarium acid (FSA) serves as a highly sensitive biomarker for the early warning of bulb rot in Lanzhou lily caused by Fusarium oxysporum infection. Realizing its highly sensitive, accurate, and rapid detection is crucial for the early warning and control of lily bulb rot. Herein, an enzyme biosensor based on the enzyme inhibition principle was developed for the rapid detection of FSA. Firstly, chitosan-functionalized carboxylated multi-walled carbon nanotubes (CS@cMWCNTS) and gold nanoparticles (AuNPs) were modified on a bare electrode by drop coating and electrochemical deposition methods, respectively. Subsequently, dopamine β-hydroxylase (DBH) was firmly immobilized on the electrode surface through the gold-sulfur bond. Because the activity of DBH can be inhibited by FSA, which leads to a noticeable change in the signal response during the conversion of dopamine (DA) to norepinephrine (NA). Under optimized experimental conditions, the sensor exhibits an excellent linear relationship in the concentration range of 1.00 × 10−5 μg ml−1 ∼ 1.00 × 103 μg ml−1 with the correlation coefficient of 0.9856 and the detection limit is 4.60pg ml−1. Additionally, the sensor showed good stability, repeatability (RSD 1.85%), and selectivity. The method was applied to analyze FSA in the extraction from Lanzhou lily with a recovery higher than 97.59% and RSD less than 1.383%. This method enables the highly sensitive and rapid detection of FSA in real samples, and provides scientific basis and technical support for early warning of diseases and accurate implementation of prevention and control strategies in crop planting and production.

Nitrated benzothiadiazole-based D-A electrochromic polymers with tunable spectral properties

Nitrated benzothiadiazole (BT) is the promising acceptor units in constructing D-A-D electrochromic polymers, but its researches in the electrochromic field was very limited so far. In this work, four kinds of nitrated polymer precursors (Th-NO2-BT, EDOT-NO2-BT, Th-2NO2-BT, and EDOT-2NO2-BT) were synthesized by Stille coupling reaction with EDOT and thiophene units as the end groups (electron donor units) and mono-nitrated benzothiadiazole and di-nitrated benzothiadiazole as the core groups (electron acceptor units). The chemical structure and optical properties of the precursor were investigated by means of 1H NMR, UV–vis absorption and fluorescence spectra; the corresponding mono-nitrated polymer films were obtained in CH2Cl2-Bu4NPF6 system by electrochemical deposition method. The optical band gap of di-nitrated polymer precursor is obviously larger than the corresponding mono-nitrated polymer precursor (both ultraviolet and fluorescence spectra are obviously blue-shifted), accompanied with the obvious increased initial oxidation potential. Due to the fluorescence quenching effect of -NO2 group, their absolute quantum yields are all very low (0.0006–0.015). The spectroelectrochemistry and electrochromic kinetics of mono-nitrated polymer films (P(Th-NO2-BT) and P(EDOT-NO2-BT)) were studied. It was found that P(EDOT-NO2-BT) can show better electrochromic performance than P(Th-NO2-BT), with dark green in the neutral state and more obvious electrochromic performance in the near-infrared region (optical contrast: 38.4 %, coloration efficiency: 129.1 cm2/C, and fast response time: 1.4 s). This systematically study about the effects of nitro substitution effect on the properties of D-A electrochromic polymers, which will further expand the selection of the new acceptor units and the application prospect of nitrated electrochromic materials.

Interfacial Electrochemistry of Catalyst-Coordinated Graphene Nanoribbons.

The immobilization of molecular electrocatalysts on conductive electrodes is an appealing strategy for enhancing their overall activity relative to those of analogous molecular compounds. In this study, we report on the interfacial electrochemistry of self-assembled two-dimensional nanosheets of graphene nanoribbons (GNR-2DNS) and analogs containing a Rh-based hydrogen evolution reaction (HER) catalyst (RhGNR-2DNS) immobilized on conductive electrodes. Proton-coupled electron transfer (PCET) taking place at N-centers of the nanoribbons was utilized as an indirect reporter of the interfacial electric fields experienced by the monolayer nanosheet located within the electric double layer. The experimental Pourbaix diagrams were compared with a theoretical model, which derives the experimental Pourbaix slopes as a function of parameter f, a fraction of the interfacial potential drop experienced by the redox-active group. Interestingly, our study revealed that GNR-2DNS was strongly coupled to glassy carbon electrodes (f = 1), while RhGNR-2DNS was not (f = 0.15). We further investigated the HER mechanism by RhGNR-2DNS using electrochemical and X-ray absorption spectroelectrochemical methods and compared it to homogeneous molecular model compounds. RhGNR-2DNS was found to be an active HER electrocatalyst over a broader set of aqueous pH conditions than its molecular analogs. We find that the improved HER performance in the immobilized catalyst arises due to two factors. First, redox-active bipyrimidine-based ligands were shown to dramatically alter the activity of Rh sites by increasing the electron density at the active Rh center and providing RhGNR-2DNS with improved catalysis. Second, catalyst immobilization was found to prevent catalyst aggregation that was found to occur for the molecular analog in the basic pH. Overall, this study provides valuable insights into the mechanism by which catalyst immobilization can affect the overall electrocatalytic performance.

LiFe0.3Mn0.7PO4-on-MXene heterostructures as highly reversible cathode materials for Lithium-ion batteries

Two-dimensional (2D) heterostructure materials, incorporating the collective strengths and synergetic properties of individual building blocks, have attracted great interest as a novel paradigm in electrode materials science. The family of 2D transition metal carbides and nitrides (e.g., MXenes) has become an appealing platform for fabricating functional materials with strong application performance. Herein, a 2D LiFe0.3Mn0.7PO4 (LFMP)–on-MXene heterostructure composite is prepared through an electrostatic self-assembly procedure. The functional groups on the surface of MXenes possess highly electronegative properties that facilitate the incorporation of LFMPs into MXenes to construct heterostructure composites. The special heterostructure of nanosized-LiFe0.3Mn0.7PO4 and MXene provides rapid Li+ and electron transport in the cathodes. This LiFe0.3Mn0.7PO4-3.0 wt% MXene composite can exhibit an excellent rate capability of 98.3 mAh g−1 at 50C and a very stable cycling performance with a capacity retention of 94.3 % at 5C after 1000 cycles. Furthermore, NaFe0.3Mn0.7PO4-3.0 wt% MXene with stable cyclability can be obtained by an electrochemical conversion method with LiFe0.3Mn0.7PO4-3.0 wt% MXene. Ex-situ XRD suggests that LiFe0.3Mn0.7PO4-on-MXene achieves a highly reversible structural evolution with a solid solution phase transformation (LFMP→LixFe0.3Mn0.7PO4 (LxFMP), LxFMP→LFMP) and a two-phase reaction (LxFMP←→Fe0.3Mn0.7PO4 (FMP)). This work provides a new direction for the use of MXenes to fabricate 2D heterostructures for lithium-ion batteries.

Corrosion and corrosion-friction effects induced by cutting fluid on binderless WC matrix composite and cemented carbide

The corrosion behavior of WC-4.3wt.%MgO-2wt.%ZrO2 composite in alkaline solution with 5% oil-based cutting fluid as medium was studied by electrochemical and microstructure analysis methods. The results showed that WM2Z composite has better corrosion resistance than YG3 and YG6 in alkaline environment. A stable passivation film was formed inside the WC phase after dissolution on the surface, which was the key reason for its high corrosion resistance. However, large areas of WC phase fell off in cemented carbide. In the process of corrosion-friction coupling experiment, due to the more excellent corrosion resistance and mechanical properties of WM2Z composites, the corrosion resistance and friction properties of WM2Z composites are better than that of YG3 cemented carbide. The corrosion-friction coupling effect on WM2Z was low, and the degree of damage to the topography after the experiment was relatively light.

Investigation of the Performance and Stability of Self-Powered Polythiophene-Based Photodiodes under UV and Visible Light Illumination

In this study, we fabricated polythiophene (PTh) and silver-decorated polythiophene (Ag@PTh) films on n-type silicon substrates using the electrochemical deposition method to investigate their electrical and photoelectrical properties in metal/interlayer/n-Si heterostructures under various conditions. The physical properties of the films were comprehensively investigated through UV-Vis, Raman, XPS and SEM analysis. The results from these analyses confirmed the successful deposition and formation of the films on the n-Si substrates. Additionally, a comparison of the current-voltage (I-V) characteristics of the PTh/n-Si and Ag@PTh/n-Si devices was conducted under both dark conditions and illumination with visible and UV light. While both devices exhibited typical rectifying diode behavior, the Ag@PTh/n-Si device demonstrated greater rectification with a RR of 2.49⁎105 at ± 2V under dark conditions. In addition, the Ag@PTh/n-Si device, with self-powered property, displayed notably enhanced performance metrics, including a significantly higher on/off ratio, responsivity, and detectivity, particularly evident under UV light illumination when compared to white light. Furthermore, to assess the long-term reliability of these devices, stability tests were conducted by repeating the I-V measurements after 90 days under identical conditions. The Ag@PTh/n-Si device exhibited considerably better stability over time than the PTh/n-Si device, maintaining consistent performance without notable degradation. So, in light of the findings, it can be concluded that the Ag@PTh/n-Si device has substantial potential for advancing optoelectronic technology.

Optimal Design of a Binder-Free Manganese/Cobalt Bilayer Bifunctional Catalyst for Rechargeable Zinc–Air Batteries

We have developed a bilayer film comprising cobalt oxyhydroxide (CoOOH) underlayer and manganese dioxide (MnO2) upper layer, which are active toward oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), respectively. The bilayer bifunctional catalyst is synthesized by electrodepositing cobalt hydroxide (Co(OH)2) on a porous carbon paper (CP) and subsequently immersing the obtained Co(OH)2/CP in a potassium permanganate (KMnO4) solution without binders or conductive additives. Specifically, electron transfer between the already-deposited Co(OH)2 and MnO4 – proceeded in the solution, yielding MnO2, until all the Co ions become trivalent, after which self-terminates. The proposed method only allows for the construction of the minimum required bifunctional catalyst only at the reaction site of the gas-diffusion electrode, i.e., at the so-called three-phase interface, thus remarkably increasing catalyst utilization while improving reactant and product diffusions. The developed catalyst shows stable MnO2/CoOOH cycles at |20| mA cm–2 with a minimal difference (0.764 V) between the OER and ORR potentials, reflecting the structural advantage of the proposed catalyst. This work proposes efficient bifunctional catalysts having spatially separated OER/ORR reactive sites that can be synthesized via the simple and scalable electrochemical method, which does not require the skill and optimization of binder and electron-conducting additives.