Rct Value Research Articles

Development and Optimization of a Cost-Effective Electrochemical Immunosensor for Rapid COVID-19 Diagnosis

The coronavirus disease (COVID-19) pandemic has created an urgent need for rapid, accurate, and cost-effective diagnostic tools. In this study, an economical electrochemical immunosensor for the rapid diagnosis of COVID-19 was developed and optimized based on charge transfer resistance (Rct) values obtained by electrochemical impedance spectroscopy (EIS) from the interaction between antibodies (anti-SARS-CoV-2) immobilized as a bioreceptor and the virus (SARS-CoV-2). The sensor uses modified pencil graphite electrodes (PGE) coated with poly(4-hydroxybenzoic acid), anti-SARS-CoV-2, and silver nanoparticles. The immobilization of anti-SARS-CoV-2 antibodies was optimized at a concentration of 1:250 for 30 min, followed by blocking the surface with 0.01% bovine serum albumin for 10 min. The optimal conditions for virus detection in clinical samples were a 1:10 dilution with a response time of 20 min. The immunosensor responded linearly in the range of 0.2–2.5 × 106 particles/μL. From the relationship between the obtained signal and the concentration of the analyzed sample, the limit of detection (LOD) and limit of quantification (LOQ) obtained were 1.21 × 106 and 4.04 × 106 particles/μL, respectively. The device did not cross-react with other viruses, including Influenza A and B, HIV, and Vaccinia virus. The relative standard deviation (RSD) of the six immunosensors prepared using the shared-pool sample was 3.87. Decreases of 22.3% and 12.4% were observed in the response values of the ten immunosensors stored at 25 °C and 4.0 °C, respectively. The sensor provides timely and accurate results with high sensitivity and specificity, offering a cost-effective alternative to the existing diagnostic methods.

A comparative study on the structural, chemical, morphological and electrochemical properties of α-MnO2, β-MnO2 and δ-MnO2 as cathode materials in aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) are considered to be highly promising electrochemical energy storage device due to their affordability, inherent safety, large zinc resources, and optimal specific capacity. Among various cathode materials, manganese dioxide (MnO2) stands out for its high voltage, environmental benignity, and theoretical specific capacity. This study systematically investigates the phase formation and structural parameters of α-MnO2, β-MnO2, and δ-MnO2 synthesized via hydrothermal method, employing Rietveld refinement. FTIR and Raman spectroscopy confirms Mn-O and O-H bond formation. BET analysis reveals surface areas, and pore size distribution is calculated with BJH method. High-resolution XPS spectra exhibit a spin energy split of ~ 11.9 eV for Mn 2p confirming the presence of MnO2. Electrochemical studies shows an initial discharge capacities of 230.5, 188.74 and 263.30 mAh g− 1 at 0.1 A g− 1 for α-MnO2, β-MnO2 and δ-MnO2. The EIS spectra revealed the capacitive behaviour and electrode reaction kinetics where a RcT value of 484.14, 327.6, 162.5 Ω for α-MnO2, β-MnO2 and δ-MnO2. These study give insights into relation of various properties of MnO2 with electrochemical performance and its viability in grid storage applications.Graphical

Mixed metal conductive MOFs constructed from Trypan blue linked metal nodes: characteristic features and electrochemical performance

Scheme shows the incorporation of Trypan blue (Try) as an organic linker in designing bimetallic organic frameworks. Rct values indicate 3d–3d MOFs can achieve a more conductive network compared to 3d–4f MOFs.

Sulfonated reduced graphene oxide encapsulated perovskite-type ErCoFe oxide nanoparticles for efficient electrochemical water oxidation.

Perovskite oxides play a vital role as electrocatalysts in water oxidation due to their flexible and unique electronic structures. In this work, Er-based perovskites ErCo1-xFexO3-δ (x = 0.0, 0.1, 0.3, 0.5, 0.7, and 1.0) denoted as EC, ECF-0.9, ECF-0.7, ECF-0.5, ECF-0.3, and EF, respectively, are synthesized by the sol-gel method. Then, ECF-0.9 is supported on sulfonated reduced graphene oxide (S-rGO) by a hydrothermal method, with weight ratios of 1 : 1 and 3 : 1 of ECF/0.9 to S-rGO (shown as ECF-0.9/S-rGO(50%) and ECF-0.9/S-rGO(75%), respectively). The structural properties and the morphology of the synthesized materials are studied using a series of different techniques. The prepared perovskites are then used as electrode materials for electrochemical water oxidation. ECF-0.9 reveals better activity than pure EF, EC, and other perovskite oxides in terms of overpotential, Tafel slope, electrochemically active surface area (ECSA), and charge transfer resistance (Rct) values. Interestingly, when the optimized perovskite oxide catalyst ECF-0.9 is decorated on S-rGO sheets, the water oxidation activity is significantly improved. ECF-0.9/S-rGO(75%) exhibits superior activity for water oxidation with an overpotential of 290 mV@10 mA cm-2 and a Tafel slope of 41 mV dec-1. Finally, overall water splitting with ECF-0.9/S-rGO(75%) as the anode electrode shows a low electrolysis voltage of 1.60 V, alongside excellent stability for 20 h.

Development of micro-nanostructured film with antibacterial, anticorrosive and thermal conductivity properties on copper surface.

A micro-nano sharkskin like film (Cu-MNS-FA) was synthesized on copper surface through chemical etching followed by formate passivation, and its anticorrosive, antibacterial and thermal conductivity properties were investigated. Results show that after 7 d of exposure to nature, Pseudomonas aeruginosa and Desulfovibrio vulgaris seawater, the charge transfer resistance of Cu-MNS-FA is more than three times higher than that of unmodified copper. In particular, in D. vulgaris seawater, the Rct value of modified copper is 7 times higher than that of unmodified copper after the same exposure duration. The counts of sessile cells, specifically P. aeruginosa and D. vulgaris, on the surface of modified copper are reduced by > 88% after 3days of immersion. Furthermore, thermal conductivity remains 10% higher than that of untreated copper after 7 d of immersion. This film improves the performance characteristics of copper in seawater heat exchange systems.

Effective Nitrate Electroconversion to Ammonia Using an Entangled Co3O4/Graphene Nanoribbon Catalyst.

There has been huge interest among chemical scientists in the electrochemical reduction of nitrate (NO3-) to ammonia (NH4+) due to the useful application of NH4+ in nitrogen fertilizers and fuel. To conduct such a complex reduction reaction, which involves eight electrons and eight protons, one needs to develop high-performance (and stable) electrocatalysts that favor the formation of reaction intermediates that are selective toward ammonia production. In the present study, we developed and applied Co3O4/graphene nanoribbon (GNR) electrocatalysts with excellent properties for the effective reduction of NO3- to NH4+, where NH4+ yield rate of 42.11 mg h-1 mgcat-1, FE of 98.7%, NO3- conversion efficiency of 14.71%, and NH4+ selectivity of 100% were obtained, with the application of only 37.5 μg cm-2 of the catalysts (for the best catalyst ─Co3O4(Cowt %55)GNR, only 20.6 μg cm-2 of Co was applied), confirmed by loadings ranging from 19-150 μg cm-2. The highly satisfactory results obtained from the application of the proposed catalysts were favored by high average values of electrochemically active surface area (ECSA) and low Rct values, along with the presence of several planes in Co3O4 entangled with GNR and the occurrence of a kind of "(Co3(Co(CN)6)2(H2O)12)1.333 complex" structure on the catalyst surface, in addition to the effective migration of NO3- from the cell cathodic branch to the anodic branch, which was confirmed by the experiment conducted using a H-cell separated by a Nafion 117 membrane. The in situ FTIR and Raman spectroscopy results helped identify the adsorbed intermediates, namely, NO3-, NO2-, NO, and NH2OH, and the final product NH4+, which are compatible with the proposed NO3- electroreduction mechanism. The Density Functional Theory (DFT) calculations helped confirm that the Co3O4(Cowt %55)GNR catalyst exhibited a better performance in terms of nitrate electroreduction in comparison with Co3O4(Cowt %75), considering the intermediates identified by the in situ FTIR and Raman spectroscopy results and the rate-determining step (RDS) observed for the transition of *NO to *NHO (0.43 eV).

One-pot synthesis of 2D-Ni-MOF from waste PET plastic in aqueous medium for selective electrooxidation of glycerol, ethanol, and methanol

This study investigates the electrochemical performance and selectivity of a nickel-based metal-organic framework (Ni-MOF) catalyst synthesized from waste PET plastic using a one-pot approach in aqueous media. The Ni-MOF electrode was evaluated for glycerol electrooxidation reaction (GEOR), ethanol electrooxidation reaction (EEOR), and methanol electrooxidation reaction (MEOR). Linear sweep voltammetry (LSV) revealed current densities of 30mA/cm² at 0.5639V for GEOR, 50.07mA/cm² at 0.35V for EEOR, and 45.73mA/cm² at 0.39V for MEOR, indicating superior catalytic activity. Nyquist plots showed lower charge transfer resistance (Rct) values of 11.0 Ω for GEOR, 2.79 Ω for EEOR, and 2.69 Ω for MEOR, confirming efficient electron transfer. Bode impedance plots demonstrated lower impedance for alcohol electrooxidation compared to oxygen evolution reaction (OER). Chronoamperometry (CA) tests indicated excellent stability with 75.72% glycerol conversion for GEOR and selectivities of 94% for glyceric acid, 65.59% for acetic acid in EEOR, and 70.54% for formic acid in MEOR. These results highlight the potential of Ni-MOF derived from recycled PET plastic for sustainable and efficient electrooxidation of C1-C3 alcohols.

Covalent triazine frameworks as particle electrode for three-dimensional photoelectrocatalytic degradation of oxytetracycline: Synergy effects, pathway, and mechanism.

Photoelectrocatalysis has been widely employed for degrading antibiotics due to its high efficiency. However, the application is significantly impeded by the rapid recombination of photogenerated charge carriers and the limited surface areas of photoelectrodes. In the study, high crystallinity covalent triazine frameworks were fabricated at low temperature of 150°C and firstly used as particle photoelectrode in the three-dimensional photoelectrochemical reactor to degrade oxytetracycline (OTC). SEM, TEM, XRD, XPS, and FT-IR confirmed the successful synthesis of high crystallinity covalent triazine frameworks. Compared to CTF-120 (71.2%) and CTF-180 (46.9%), CTF-150 exhibited excellent OTC removal. Electrochemical impedance, UV-vis absorption spectra, and Mott-Schottky tests showed that CTF-150 demonstrated more wide light absorption range of 501nm and narrow bandgap of 2.52eV, and smaller Rct value under illumination, in comparing to CTF-120 and CTF-180. When the initial concentration of OTC was 50mgL-1, the 86.2% of OTC removal and 62.7% of mineralization were obtained under light irradiation (λ>420nm), current of 10mA, pH of 6.4, electrolyte of 0.1M Na2SO4. The synergy effect between photocatalytic and electrocatalytic processes of CTF-150 not only enhanced by 38.5% current efficiency but also reduced energy consumption to 1.90 kWh m-3. CTF-150 had a wide range of acid-base application and displayed resistance on coexisting ions. Electron spin resonance detection, quenching experiments, and probe experiments illustrated that h+, •O2-, 1O2, and •OH contributed to the degradation of OTC and the generation pathways of •O2-, 1O2, and •OH were verified. Moreover, •O2-, 1O2, and h+ were the main reactive species responsible for OTC removal, while 1O2 was for OTC mineralization. Based on high-performance liquid chromatography-tandem mass spectrometry detection, OTC with benzene ring was decomposed to opening ring products. The acute toxicity, developmental toxicity, bioaccumulation factor and mutagenicity of OTC and its intermediates using T.E.S.T. showed the toxicity of 82.35% degradation products decreased.

Synergistic electrochemical performance of textile sludge based activated carbon with reduced graphene oxide as electrode for supercapacitor application

The procedure for disposing of textile waste sludge requires sustainable solutions due to numerous environmental issues associated with its disposal. The majority of textile manufacturers incinerate the waste sludge to meet their heating demands, which is harmful to the environment. It can also be used in soil amendment, biodegradable products, construction material and water treatment process as absorbent to remove the heavy metals etc. In this study we use the heavy metal containing textile waste sludge as a precursor for the fabrication of functional electrode material for supercapacitor applications. In this process the organic content within the textile sludge waste is treated at 900 °C and transformed into activated carbon, a vital component of supercapacitors electrodes. Through a series of pyrolysis and activation processes, it is further converted into porous activated carbon (AC) with a wide surface area and appropriate electrochemical properties. To enhance the overall conductivity of the electrode material for supercapacitor applications, the carbon content of the material is increased by loading of reduced graphene oxide (rGO) up to 4 wt%. It resulted in a significant increase in the surface area up to 128.68 m2/g. The effective conversion and relevance of the obtained material for supercapacitor applications is further reinforced by the excellent electrochemical performance of rGO@AC-900 °C which generated a specific capacitance of 362F/g with 4 wt% loading which is higher than the specific capacity achieved with lower rGO loading i.e., 83.2 F/g and 182.5 F/g for AC-900 °C and 2 wt% rGO@AC-900 °C, respectively. The 4 wt% rGO@AC900°C also represented improved stability with up to 82 % charge retention after 5000 charge–discharge cycles. The excellent EDLC behavior of 4 wt% rGO@AC900°C is also evident from the impedance data. The electrode material with 4 wt% rGO loading showed lower value of RCT i.e., 4.16 Ω as compared to 12.08 Ω with 2 wt% rGO loading. This novel approach offers a sustainable alternative for the handling of hazardous textile waste sludge through conversion into a potential electrode material for environmentally friendly energy storage devices.

In-depth investigation of corrosion inhibition mechanism: Computational, electrochemical, and theoretical studies of vanillin meldrum’s acid on mild steel surface in 1 M HCl

Vanillin Meldrum’s acid (VanMA) was successfully synthesized and thoroughly examined using techniques like elemental analysis, FTIR, NMR, UV–Vis spectroscopies, and single crystal X-ray diffraction. It crystallizes in a triclinic crystal system under the P-1 space group. A quantitative analysis of the intermolecular interactions in the crystal structures was performed using Hirshfeld surface analysis, which reveals that H···H contacts are the most significant contributing 43.2 % and the O···H/H···O contacts contributing 36.2 % of the total Hirshfeld surfaces. VanMA proved effective as a corrosion inhibitor in 1 M HCl, demonstrating a 62.19 % inhibition efficiency at an optimal concentration of 0.1 mM. It creates a protective layer on mild steel surfaces, adhering to the Freundlich adsorption isotherm (R2 = 0.9983) and displaying a physical adsorption mechanism (−12.72 kJ/mol). The corrosion inhibition efficacy of VanMA (0.1 mM) decreases in 1 M HCl as the temperature increases from 303 to 383 K. A shift towards physisorption is indicated by the increase in activation energy (Ea) from 12.37 to 16.42 kJ/mol. VanMA’s adsorption efficacy reduces at higher temperatures, increasing surface exposure and corrosion rates, but increasing activation enthalpy (ΔH° = 31.32 kJ/mol) and ΔS° = −113.63 J mol−1 K−1). The diameter of the semicircle rose as the concentration of VanMA increased, indicating that VanMA adsorption is responsible for the mild steel surface’s greater resistance to corrosion with increasing Rct values from 224 to 641 Ω cm2 and decreasing capacitance double layer (Cdl) values from 4.480 × 10−5 to 1.560 × 10−5 μFcm2, confirming VanMA’s efficacy as a corrosion inhibitor at 65.05 %. The SEM-EDX and AFM images show the smoother mild steel surface at 0.1 mM VanMA. VanMA was verified as a mixed-type inhibitor by showing shifts of less than 85 mV with respect to the blank PDP. The inhibition efficiency (IE%) increased up to 77.89 % while the icorr values decreased to 1.1850 × 10−5 A/cm2 as the VanMA concentration rose. In XPS, the presence of VanMA was identified by the presence of FeO (713.60 eV) and CO (287.93 eV), which signifies the adsorption of VanMA onto mild steel by the O atom and the negatively charged O ion via a mixed adsorption. DFT and Mulliken population analysis deduced that the VanMA interacted with the mild steel through mixed adsorption. VanMA adsorbs almost parallel to the Fe (1 1 0) surface, forming a barrier that protects from corrosion, according to the MD modeling. While the significant negative adsorption energy (−309.490 kcal/mol) verifies the stability and spontaneity of the adsorption process.

Synthesis and surface engineering of carbon-modified cobalt ferrite for advanced supercapacitor electrode materials

The precise design and surface modification of electrode materials are crucial challenges for advancing the supercapacitor technology. In this study, we report a straightforward two-step process for the synthesis of a cobalt ferrite (CoFe2O4)/carbon hetero nanostructure. The CoFe2O4 nanoparticles were first synthesized using a simple chemical oxidation method, followed by carbon modification using glucose. The modified samples were calcined at 400 and 600 °C for 4 h in N2 atmosphere to optimize the structural and electrochemical properties. The increase in the grain size of carbon modified cobalt ferrite magnetic nanoparticles (MNPs) was observed from 22 to 28 nm with post annealing temperature. The presence of carbon was confirmed by the FTIR spectroscopy, FESEM and TEM analyses. The carbon decoration on the cobalt ferrite partially showed a core–shell like morphology. The saturation magnetization of bare cobalt ferrite was observed to be 76 emu/g and the same was decreased by the surface modification with carbon. A high specific capacitance of 323 F/g was observed for the carbon-modified cobalt ferrite MNPs annealed at 600 °C. The electrochemical impedance spectroscopy (EIS) analysis demonstrated that the charge-transfer resistance (Rct) decreased significantly in the carbon-modified CoFe2O4 MNPs, particularly for the sample annealed at 600 °C, with an Rct value of 17 Ω. The carbon layer effectively enhanced conductivity and reduced the electrode/electrolyte interface, led to the improved electrochemical performance, as reflected in the enhanced specific capacitance. An improved capacitance retention of 84 % was achieved in the case of carbon-modified cobalt ferrite MNPs based electrode even after 4000 cycles. The study suggested that the prepared carbon-modified cobalt ferrite MNPs stand in the limelight as a better candidate electrode material for the electrochemical applications.

Enhanced HER activity through FeAlO3 perovskite oxide incorporated with conducting polymer PANI

The advancement of reliable and economical catalysts for hydrogen evolution reaction (HER) is beneficial for progress of H2 production technology. In the current work, conducting polyaniline (PANI) polymerwas coated on the FeAlO3 via hydrothermal approach to improve its catalytic behavior. The generated electrocatalyst (FeAlO3/PANI) have been examined via different physicochemical characterization analysis, including X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical analysis, to determine their crystalline phase uniformity,morphology and electrochemical performance for HER. It is reported that FeAlO3/PANI composite exhibits higher HER behavior in 1.0 M KOH. Furthermore, as-produced composite material achieved smaller overpotential (−165 mV), with Tafel value of 62 mV/decto achieve a −10 mA/cm2current density. The HER on FeAlO3/PANI composite obeyed Volmer–Heyrovsky mechanism. The FeAlO3/PANI composite illustrates an enhanced surface area of 933.75 cm2 and smaller Rct value of 0.08Ω cm2. Chronopotentiometry shows no significant decline in current density over 35 h in an alkaline electrolyte. The findings of this work reveal an innovative, durable and efficient electrocatalyst with potential applications in development of electrocatalytic systems for H2 gas generation. This innovative electrocatalyst can help to substitute noble metal-based electrocatalysts for practical usage in energy conversion/storage technologies.

Sol–Gel Fabrication of Sm‐Doped MnTiO3 Perovskite Electrode for Enhanced Oxygen Evaluation Reaction

ABSTRACTExcessive usage of fossil fuels has led to significant depletion, creating an energy crisis and environmental concerns. This has prompted the creation of sustainable energy conversion systems. This study explores sol–gel incorporation of Sm‐doped MnTiO3 nanostructure, which exhibits OER activity. Different analytical techniques were used to assess the material's morphology, structure, and textural properties. BET analysis confirmed increased surface area (34 m2 g−1) of Sm‐doped MnTiO3 nanostructure, which enhanced OER performance. The electrochemical results showed that the fabricated doped nanostructure had a lower overpotential of 201 mV, resulting in a current density of roughly 10 mA cm−2 and a Tafel slope of 40 mV dec−1. In EIS analysis, a low Rct value of Sm‐doped MnTiO3 (0.20 Ω) compared with pure MnTiO3 (0.23 Ω) indicates highly efficient charge transfer and a faster faradaic reaction. Chronoamperometry and cyclic stability analyses of Sm‐doped MnTiO3 nanostructure demonstrate stability over 35 h. The fabricated nanostructure has remarkable electrochemical characteristics, making it a promising material for future applications in electrical and other areas.

3D printer fabrication of boron doped Cu-MWCNT/PLA electrodes: Investigation of its efficiency in electrocatalytic hydrogen production

In this study, three-dimensional (3D) electrodes based on MWCNT-Cu/PLA with high electrocatalytic efficiency, large surface area and different amounts of nano‑boron doped MWCNT-Cu/PLA were fabricated using Fused Granular Fabrication (FGF) method with a 3D printer. When FE-SEM images are examined, MWCNT fibers and copper particles are seen more clearly on the surface due to the formation of more dense conductive networks between the conductive carbon fibers trapped in the PLA structure due to the increasing amount of boron. When XRD results are examined, it is observed that the characteristic peaks belonging to the face-centered cubic structure of Cu are dominant and the crystal size increases as MWCNT addition and boron doping increase. When Raman spectra were analyzed to investigate the internal structural changes of MWCNTs, three characteristic bands corresponding to the D band (defect), G band (graphite band) and G' band (D overtone) of MWCNTs were determined and it was observed that the ID/IG ratio decreased with increasing boron doping compared to MWCNT-Cu/PLA electrode. The B1s spectrum of the 3D 0.8B@MWCNT-Cu/PLA electrode confirmed the presence of boron with the peak corresponding to B@C bonds at 191.2 eV. The obtained 3D electrocatalysts were used as cathodes in an electrolysis cell in aqueous solution containing 1 M KOH and their catalytic efficiency in hydrogen evolution reaction (HER) was tested. In order to increase the activity of the 3D electrodes, unlike the literature, they were activated by electrochemical activation process without using organic solvent and HER measurements of the activated electrodes were performed. Before activation, the charge transfer resistance (Rct) value of the Cu/PLA electrode, which was 6219.00 Ω cm−2, decreased to 681.90 Ω cm−2 after 5 % MWCNT doping. It is seen that with boron doping, a greater decrease in Rct value is realized, reaching values of 66.50–74.56 Ω cm−2. The cathodic Tafel slopes show that the Volmer reaction is the rate-determining step for HER and the rate-determining step is the electrochemical adsorption of hydrogen on the metal surface. In addition, energy efficiency tests of the 3D electrodes in HER were also performed and electrochemically active surface areas were determined. Thus, this study has taken an important step toward using 3D electrocatalysts, which are produced with more cost and more flexible designs, unlike previous production techniques, for hydrogen energy production.

Voltammetric determination of uric acid using a miniaturized platform based on screen-printed electrodes modified with platinum nanoparticles

Disposable and sensitive screen-printed carbon electrodes (SPCE) modified with multi-walled carbon nanotubes (MWCNT) and platinum nanoparticles (PtNPs) were constructed to analyse uric acid (UA) in biological samples using a miniaturized smartphone potentiostat system. Combining the nanomaterials with Nafion™ yielded a stable dispersion that could be successfully used as an electroactive layer. Transmission electron microscopy (TEM) and energy dispersive scanning (EDS) were used to characterize the morphology of PtNPs. These revealed approximately spherical shapes with emission lines characteristics of platinum. Furthermore, PtNPs/MWCNT/SPCE film was characterized by scanning electron microscopy (SEM), which demonstrated the tubular characteristic of MWCNT distributed and covered by carbon black (CB) spheres present in the screen-printed ink. An enhanced current response was observed for UA voltammetric analysis, especially due to the synergism effect of PtNPs and MWCNT, which reduced the Rct value. The values of Dapp (1.6 × 10−6 cm2/s) and kcat (2.76 × 103 mol−1 L/s) were determined for UA using the proposed sensor. The sensor displayed linear response for UA in the range from 5.0 × 10−6 mol/L to 6.9 × 10−4 mol/L, with a detection limit of 4.9 × 10−7 mol/L. Along with detectability, excellent performances were verified in terms of repeatability, anti-interference features, and analysis of UA in the biological samples.

New Brønsted–Lowry acid Co(II) complexes: Synthesis, characterization, and investigation of electrochemical application for sensing of salbutamol

In recent years, the employment of transition metal complexes for working electrode surface modification for sensor fabrication has become an area of research direction. Based on this, in this study, three Co(II) complexes: Co(phen)Cl2 (CoC12H8N2Cl2) (C1), and Brønsted–Lowry acids Co(phen)(HTA)Cl (CoC16H13N2O6Cl)(C2), and Co(phen)(HTA)2 (CoC20H18N2O12)(C3) were synthesized and characterized using various techniques such as UV–Vis, FT-IR, ICP OES, TGA, DTA, pXRD as well as electrolytic conductivity, and acid-base property analysis. C and C3 were found polycrystalline whose size falls within the nano range of 50 and 51 nm, respectively. The synthesis was intended to get materials for voltammetrically modifying glassy carbon electrodes for the determination of salbutamol. Salbutamolis a short-acting β2adrenergic receptor agonist that is applied for opening the medium and large airways in the lungs and eventually treats asthma among other problems. The electrochemical application of the synthesized materials was studied by fabricating through electropolymerization of C1, C2, and C3 on glassy carbon electrodes. The poly(C1)/GCE, poly(C2)/GCE, and poly(C3)/GCE) revealed effective surface area is 0.174 cm2, 0.183 cm2, and 0.281 cm2, respectively, and electrochemical catalysis of the materials increased with the number of the tartrate. The Rct values are 5686, 242, 216, and 185 Ω cm2, while the Cdl values are 9.93 × 10−8, 5.35 × 10−6, 1.25 × 10−5, and 2.72 × 10−5, for bare GCE, poly(C1)/GCE, poly(C2)/GCE and poly(C3)/GCE, respectively. Similarly, the rate of charge transfer (k°) increased significantly on the modified electrode compared to the bare GCE. Salbutamol demonstrated a single well-shaped irreversible oxidative peak at the modified electrodes in the ascending order of poly(C1)/GCE, poly(C2)/GCE, and poly(C3)/GCE when compared to a bare GCE.

Fluorinated reduced graphene oxide nanosheets for symmetric supercapacitor device performance

This study explores the potential of using spent lithium-ion battery anodes (graphite) for fabricating symmetric energy devices through a simple regeneration process. Specifically, the use of fluorine-doped reduced graphene oxide (RGO) nanosheets derived from waste batteries as the basis for a symmetric supercapacitor (SC) device is investigated. To enhance the electrochemical energy storage capabilities, a facile hydrothermal technique is employed to synthesize fluorinated graphene. Fluorination of the graphene sheets is successfully realized, as confirmed by the presence of boron with a 2.94 at.% fluorine-doped level, according to the Energy dispersive spectroscopy (EDS) spectrum analysis. Electrochemical analysis of the F-RGO electrode performance consistent with electric double-layer capacitance. Moreover, with a three-electrode system, the F-RGO electrode achieves a maximum specific capacitance of 207F/g under a current density of 1 A/g. A two-electrode symmetric device employing F-RGO exhibits a specific capacitance of 54F/g at 1 A/g. Furthermore, electrochemical impedance measurements demonstrate low charge transfer resistance (Rct) values, specifically 8.63 Ω for F-RGO, signifying improved electrochemical performance. Thus, fluorine atomic doping in RGO nanosheets contributes to the improvements of the specific capacitance and overall superior electrochemical performance of F-RGO, and F-RGO is a highly electrochemical active material for high-performance energy storage electrodes for SCs.

Step-by-Step Tuning of Tribological and Anticorrosion Performance of Zinc Phosphate Conversion Coatings through Effective Integration of Spherical P-Doped MoS2 Nanoparticles.

Surface coatings with enhanced mechanical stability, improved tribological performance, and superior anticorrosion performance find immense application in various industrial sectors. Herein, we report the development of multifunctional composite zinc phosphate coatings by the effective integration of a structurally and morphologically tuned P-doped MoS2 nanoparticle additive (3P-MoS2) into the zinc phosphate matrix to offer attractive characteristics suitable for industrial applications. The integration of spherical nanoparticles as additive leads to the formation of homogeneous and compact coatings with a densely packed crystalline microstructure having enhanced microhardness, distinctive leaf-like morphology, and comparatively smooth topographical features. The attractive lubricity of the additive (3P-MoS2), coupled with its spherical morphology, facilitates a transition from sliding to rolling friction and contributes significantly toward the performance enhancement of the tuned composition of the composite zinc phosphate coating (0.3-PMS). Thus, the tuned 0.3-PMS coating delivers the lowest specific wear rate (1.334 × 10-5 mm3/Nm) and coefficient of friction (0.114) that significantly outperform bare-zinc phosphate coating. Further, the electrochemical corrosion study results indicate the improvement in corrosion resistance behavior of the composite zinc phosphate coatings with reduced corrosion current density (icorr) and charge transfer resistance (Rct) values, as compared to the bare-zinc phosphate coating. The effect of passivation in conjunction with the barrier protection characteristics of the composite coatings induced by the optimal composition of the integrated additive nanoparticles (3P-MoS2) can efficiently prevent the infiltration of corrosive ions and thereby significantly reduce the rate of corrosion.

Ni–Cu Bimetallic Oxides with Tailored Morphology for High‐Performance Alkaline Water Oxidation

AbstractWater oxidation, a crucial step in electrochemical water splitting, is often hindered by its complex kinetics. In our pursuit of designing efficient electrocatalysts, we have found that morphological modifications during synthesis are powerful tools. By manipulating various parameters, such as reaction time and temperature, we have tuned the morphology of the catalysts, leading to a significant enhancement in the oxygen evolution reaction (OER) rate. Our thorough research involves using a simple hydrothermal method for synthesizing bimetallic Ni–Cu oxides, resulting in the emergence of different morphologies by varying reaction times from 4 to 24 h. The OER performance in an alkaline medium, using a 1 M KOH solution, has been meticulously investigated, and our results have unveiled the highest activity for Ni–Cu fabricated with a growth time of 24 h. Ni–Cu oxide 24 exhibits a remarkably low onset potential for OER at 222 mV with a Tafel slope of 373 mV/dec. The catalyst boasts the lowest Rct value of 2.788 ohm, ensuring faster charge transfer rates and stability up to 1000 cyclic voltammetry (CV) cycles, thereby supporting its electrochemical applications for water splitting.

Spinel-type calcium manganese oxide adorned on g-CN composite: A highly proficient electrocatalyst for oxygen evolution reaction (OER)

A comprehensive study was performed on water electrolysis to address environmental challenges and energy issues. Eco-friendly and renewable energy systems are required to produce cost-effective electro-catalysts with long-term durability and higher electrocatalytic efficiency to enhance OER. Spinel oxide has recently been used as a promising substitute for transition metal catalysts. They can function as very effective electrocatalysts in water oxidation processes. In current study, the CaMn2O4/g-CN composite was prepared using the hydrothermal technique in 1.0 M KOH in primary media. Distinctive physical and electrochemical analyses evaluated the prepared material's morphology, structure and electrocatalytic components. The composite material showed enhanced electrocatalytic efficacy for OER having a reduced overpotential (η) of 220 mV than pure CaMn2O4 278 mV and possesses a minimal Tafel value (35 mV/dec) contrasted with pristine CaMn2O4 (57 mV/dec). In case of overpotential, the composite material revealed good performance than its pure material while the Tafel slope of CaMn2O4/g-CN exhibited lower value than its individual material (CaMn2O4). Additionally, cyclic stability and chronoamperometric studies measured the electrodes' durability over 30 h. Electrochemical impedance spectroscopy (EIS) investigations indicated that charge transformation at an electrode-electrolyte surface might be feasible with minimal Rct value (0.19 Ω) and it showed excellent improved performance (63 %) better than its pure material, leading it to boost OER properties, attributed to its remarkable electrical conductivity, greater surface area and outstanding stability. These outstanding electrochemical features of the CaMn2O4/g-CN differentiate as an attractive choice for future OER utilization.