Linear Sweep Voltammetry Research Articles

Electrodeposited NiB Films as Bifunctional Electrocatalysts in Alkaline Water Electrolizer

Abstract Sustainable electrochemical energy generation requires cost-effective, noble-metal-free electrocatalysts for hydrogen and oxygen production in electrolyzers. This study used electrodeposition to create crystalline NiB films with different boron (B) contents—Ni-B(1.17 wt.%), Ni-B(1.06 wt.%), Ni-B(0.94 wt.%), and Ni-B(0.89 wt.%)—on FTO substrates. These films were tested as bifunctional electrocatalyst electrodes for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in alkaline media. The NiB films' composition and morphology were analyzed using SEM, AFM, XRD, GD-OES, and XPS. Linear sweep voltammetry assessed their electrocatalytic performance. Higher B content in the films promoted the formation of electroactive NiOOH, enhancing the OER. The Ni-B(1.17 wt.%) electrode required an overpotential of 380 mV to reach 10 mA cm⁻² for OER, while the Ni-B(1.06 wt.%) electrode required 146 mV for the same current density for HER. An alkaline water electrolyzer using Ni-B(1.17 wt.%) as the anode and Ni-B(1.06 wt.%) as the cathode achieved a current density of 10 mA cm⁻² at 1.71 V for overall water splitting. The system showed stability over 12 hours of testing. The results indicate that NiB films on FTO substrates are promising, low-cost bifunctional electrocatalysts for alkaline water electrolysis, offering an alternative to noble-metal-based electrocatalysts.

Fabrication of heterostructure multilayer devices through the optimization of Bi-metal sulfides for high-performance quantum dot-sensitized solar cells.

In this work, a titanium dioxide and lead sulfide (TiO2/PbS) nano-size heterostructure with tin sulfide was fabricated and coated via a two-step direct deposition process. Its microstructure, morphology, elemental composition, optical absorption, and photochemical activity were investigated. Linear sweep voltammetry and cyclic voltammetry curves substantiated its catalytic activity, indicating quantum dot effects of a well-developed space charge domain on the surface of the hybrid structure. These give rise to electron-hole recombination suppression and a high charge mobility rate. Moreover, direct stabilization was identified in current density, corresponding to the hybrid structures limiting the diffusion current process. Higher J SC values observed were substantiated by the role of quantum dot-size effects and enhanced crystalline structures, leading to a reduction in series resistance and an improved conversion efficiency of 10.05%. Overall, theoretical analyses and empirical findings indicated that the seamless migration of photoexcited electrons across the interfaces of SnS and PbS is linked to quantum dot effect synergy. This is facilitated by the space charge region, which serves as a conduit for efficient electron transfer between the respective materials.

Poly(o-anisidine) and poly(o-anisidine-co-aniline) polymers synthesized on the ZnFeNi alloy coated steel surface

Abstract ZnFeNi alloy was synthesized on the carbon steel surface in a sulfate bath using the galvanostatic method at a constant current of 1.5 mA for 300 seconds. Poly(o-anisidine) homopolymer and poly(o-anisidine-co-aniline) copolymer were synthesized on the ZnFeNi coated electrode surface. Poly(o-anisidine) homopolymer was synthesized in 0.05 M o-anisidine+0.2 M sodium oxalate medium, and poly(o-anisidine-co-aniline) copolymer was synthesized in 0.05 M o-anisidine+0.05 M aniline+0.2 M sodium oxalate medium. Electrochemical synthesis was carried out by cyclic voltammetry technique. The synthesized materials were characterized by electrochemical impedance spectroscopy, linear sweep voltammetry, open circuit potential-time and anodic polarization curves. Open circuit potential-time curves showed that polymer coatings had higher open circuit potential. By linear sweep voltammetry measurements, it was determined that ZnFeNi alloys were present at the base of the polymer layers after polymer synthesis. It was understood from the anodic polarization curves that the polymer coated electrodes had lower current values ​​than the uncoated ZnFeNi coated electrode, and the poly(o-anisidine) coated electrode had lower current values ​​than the poly(o-anisidine-co-aniline) coated electrode. From electrochemical impedance spectroscopy measurements, it was determined that the polarization resistance of polymer-coated electrodes was higher than the polymer-free electrode during long periods of waiting in 3.5% corrosive solution. Among the polymer-coated electrodes, it was understood that the homopolymer poly(o-anisidine) showed better corrosion performance than the poly(o-anisidine-co-aniline) copolymer.

Hydrogen Evolution Reaction of Electrodeposited Ni-W Films in Acidic Medium and Performance Optimization Using Machine Learning.

Ni-W alloy films were electrodeposited from a gluconate aqueous bath at pH = 5.0, at varying current densities and temperatures. While there is little to no difference in composition, i.e., all films possess ~12 at.% W, their activity at hydrogen evolution reaction (HER) in acidic medium is greatly influenced by differences in surface morphology. The kinetics of HER in 0.5 M H2SO4 indicates that the best performing film was obtained at a current density of -4.8 mA/cm2 and 50 ºC. The Tafel slopes (b) and the overpotentials at a geometric current density of -10 mA/cm2 (η10) obtained for 200 cycles of linear sweep voltammetry (LSV) from a set of films deposited using different parameters were fed into a machine learning algorithm to predict optimum deposition conditions to minimize b, η10, and the degradation of samples over time. The optimum deposition conditions predicted by the machine learning model led to the electrodeposition of Ni-W films with superior performance, exhibiting b of 33-45 mV/dec and and η10 of 0.09-0.10 V vs. RHE after 200 LSVs.

Photoelectrochemical and Structural Insights of Electrodeposited CeO2 Photoanodes

Cerium dioxide (CeO2) is a promising material for photoelectrochemical applications, requiring a thorough understanding of the interplay between its properties and structure for optimal performance. This study investigated the photoelectrochemical performance of CeO2 photoanodes immobilized by electrodeposition on glass substrates, focusing on the correlation between the annealing temperature and structural, optical, and electrical changes. CeO2 coatings were obtained via chronoamperometry in an aqueous solution of 25 mM CeCl3 and 50 mM NaNO₃. The photoelectrochemical characterization included the evaluation of photoactivity, current density, stability, and recombination using linear sweep voltammetry (LSV) and chronoamperometry (CA). Charge transfer resistance, flat-band potential, and capacitance were assessed through impedance spectroscopy. The optimal annealing temperature for this material was found to be 600 °C as it resulted in the lowest charge transfer resistance and increased photocurrent, which was attributed to enhanced crystallinity and variations in the Ce3+/Ce4+ ratio.

Non-enzymatic electrochemical detection of sarcosine in serum of prostate cancer patients by CoNiWBO/rGO nanocomposite

Selective and sensitive sarcosine detection is crucial due to its recent endorsement as a prostate cancer (PCa) biomarker in clinical diagnosis. The reduced graphene oxide-cobalt nickel tungsten boron oxides (CoNiWBO/rGO) nanocomposite is developed as a non-enzymatic electrochemical sensor for sarcosine detection in PCa patients’ serum. CoNiWBO/rGO is synthesized by the chemical reduction method via a one-pot reduction method followed by calcination at 500 °C under a nitrogen environment for 2 h and characterized by UV-Vis, XRD, TGA, and SEM. CoNiWBO/rGO is then deposited on a glassy carbon electrode, and sarcosine sensing parameters are optimized, including concentration and pH. This non-enzymatic sensor is employed to directly determine sarcosine in serum samples. Differential pulse voltammetry (DPV) and linear sweep voltammetry (LSV) are employed to monitor the electrochemical behavior where sarcosine binding leads to oxidation. Chronoamperometric studies show the stability of the developed sensor. The results demonstrate a wide linear range from 0.1 to 50 µM and low limits of detection, i.e., 0.04 µM and 0.07 µM using DPV and LSV respectivel. Moreover, the calculated recovery of sarcosine in human serum of prostate cancer patients is 78–96%. The developed electrochemical sensor for sarcosine detection can have potential applications in clinical diagnosis.

Semiconducting minerals participated extracellular electron transfer in red soil of Ningxia Plain, China

In recent years, exploring interactions between sunlight, semiconducting minerals and microorganisms in nature has attracted great attention. However, relatively little research has been conducted on the interaction between minerals and microorganisms in the plain areas of the Yellow River Basin under sunlight. In this study, the mineral composition and microbial community of red soil from the Ningxia Plain, China were analyzed. X–ray diffraction (XRD) results showed that red soil contained semiconducting minerals such as birnessite, hematite and goethite. 16S rRNA analysis found that electroactive microorganisms such as Proteobacteria, Firmicutes and Actinobacteriota were enriched in in–situ microbial community of red soil. Afterwards, electrochemical tests such as linear sweep voltammetry (LSV) and I–t curves, indicated that red soil exhibited good semiconducting properties under light irradiation. Finally, a dual chamber system and electrochemical techniques were used to explore the electron transfer relationship between red soil and microorganisms. The open circuit voltage (350 mV) and maximum power density (1242.72 mW/m2) of red soil cathode system were significantly improved compared to blank graphite electrode, indicating that red soil could serve as electron acceptors for microbial extracellular respiration. Red soil electrode in live bacteria exhibited the highest photocurrent density (0.29 μA/cm2) and the lowest charge transfer resistance (Rct) (223 Ω) under light conditions, indicating that red soil accelerated the rapid transfer of electrons, reduced polarization loss, and enhanced extracellular electron transfer (EET) process under light conditions. This study demonstrated that the participation of semiconducting minerals in microbial EET processes under sunlight in the Ningxia Plain, China.

Facile synthesis of nitrogen-containing multiwalled carbon nanotubes as a worth metal-free electrocatalyst for hydrogen evolution reaction and semicarbazide oxidation

Studies of metal-free carbon nanostructures prove effective in energy and environmental applications due to their molecular tunability and vast chemical space. Herein, we synthesize nitrogen-containing multi-walled carbon nanotubes (N-MWCNTs) via. acid-catalysed incorporation of 3, 4-diaminopyridine into multi-walled carbon nanotubes (MWCNTs), and demonstrating their efficacy in electrocatalytic hydrogen evolution reaction (HER) and semicarbazide (SCB) oxidation for energy and environmental waste management, respectively. Successful synthesis is further confirmed by analysis techniques, i.e. Fourier transform infrared (FTIR) spectral analysis shows the diminishing OH frequency around 3250 cm−1 in MWCNTs after functionalization and the formation of an OC–NH bond in N-MWCNTs at 1710 cm−1. X-ray diffraction (XRD) confirms the incorporation of N-species, while Raman spectroscopic analysis indicates an increase in the ID/IG ratio MWCNTs (∼1) to N-MWCNTs (∼1.25), suggesting more defective sites in the N-MWCNTs nanocomposite. X-ray photoelectron spectroscopy (XPS) reveals peaks at 399.38, 400.49, and 402.05 eV, attributed to pyridinic-N, aromatic amide-N, and protonated amine groups, respectively. N₂ adsorption-desorption studies shows a high Brunauer-Emmett-Teller (BET) surface area for N-MWCNTs (119.22 m2/g) compared to MWCNTs (74.94 m2/g). Linear sweep voltammetry (LSV) profiles demonstrate enhanced activity of N-MWCNTs for both HER and SCB oxidation at an ultralow potential of E = −0.55 V vs RHE at 10 mA/cm2, with a lower Tafel slope of 108 mV.dec−1. Moreover, the electrochemical sensing studies indicates on N-MWCNTs were demonstrating an efficient electron transfer to SCB with the lower detection limit of 0.004 μmol. This work provides carbon-based metal-free electrocatalysts for energy harvesting and environmental management.

Promoting Surface Reconstruction in Spinel Oxides via Tetrahedral-Octahedral Phase Boundary Construction for Efficient Oxygen Evolution.

Understanding the origin of surface reconstruction is crucial for developing highly efficient lattice oxygen oxidation mechanism (LOM) based spinel oxides. Traditionally, the reconstruction has been achieved through electrochemical procedures, such as cyclic voltammetry (CV), linear sweep voltammetry (LSV). In this work, we found that the surface reconstruction in LOM-based CoFe0.25Al1.75O4 catalyst was an irreversible oxygen redox chemical reaction. And a lower oxygen vacancy formation energy (EO-V) could benefit the combination of the activated lattice oxygen atoms with adsorbed water molecular. Motivated by this finding, a strategy of phase boundary construction from Co tetrahedral to octahedral was employed to decrease EO-V in CoFe0.25Al1.75O4. The results showed that as the Co octahedral occupancy ratio rose to 64 %, a 3.5 nm-thick reconstructed layer formed on the catalyst surface with a 158 mV decrease in overpotential. Further experiments indicated that the coexistence of tetrahedral-octahedral (O-T) phase would result in lattice mismatch, promoting non-bonding oxygen states and lowering EO-V. Then more active lattice oxygen combined with H2O molecules to generate hydroxide ions (OH-), followed by soluble cation leaching, which enhanced the reconstruction process. This work provided new insights into the relationship between the intrinsic structure of pre-catalysts and surface reconstruction in LOM-based spinel electrocatalysts.

Enhanced photoelectrochemical CO2 reduction activity towards selective generation of alcohols over CuxO/SrTiO3 heterojunction photocathodes

Photoelectrochemical reduction (PECR) of CO2 to value-added chemicals and fuels will reduce the dependency on fossil fuels, also it will solve environmental issues that arise due to greenhouse gases. A heterojunction of CuxO/SrTiO3 with varying post-annealing temperature ranges from 300 to 600 °C (CS300-600) was synthesized by overlying the spin-coated SrTiO3 on electrodeposited Cu2O over the FTO glass substrate. The synthesized photoelectrode's crystallinity and phase formation significantly varied by varying the post-annealing temperature, which was characterized via XRD and Raman spectroscopy. Optical, morphological, type of heterojunction formation and elemental surface oxidation states of photoelectrodes were studied through UV–visible DRS spectrum, FE-SEM, and XPS analysis respectively. Electrocatalytic analysis such as Linear Sweep Voltammetry (LSV), and Electrochemical Impedance Spectrometry (EIS) was employed, thus it conforms to the highest photocurrent density (−1.38 mA/cm2 at −0.6V vs. Ag/AgCl), and low charge transfer resistance (RCT=0.412 kΩ) at the electrode-electrolyte interfaces for CS500 photoelectrode as compared to others photoelectrodes. PECR of CO2 to liquid product formation was evaluated by applying different potential ranges (0 to −0.6 V vs. Ag/AgCl). Highest methanol formation of 48.69 μmol.cm−2hr−1, which is approximately 9 times enhanced as compared to the pure Cu2O (5.62 μmol.cm−2hr−1) photoelectrode at 0 V vs Ag/AgCl for CS500 heterojunction. Optimization of overlaying SrTiO3 synthesis temperature for crystallization formation on Cu2O and applied photoelectrode potential findings could pave the way for designing other new heterojunction types for selective liquid alcohol production.

Electrochemical Behavior of Tantalum Nitride Protective Layers for PEMFC Application

Proton Exchange Membrane Fuel Cells (PEMFCs) are promising technology to convert chemical energy from dihydrogen in electrical energy. HT-PEMFCs are working at high temperatures (above 120 °C) and with doped orthophosphoric acid H3PO4 PBI membranes. In such devices, bipolar metallic plates are used to provide reactive gas inside the fuel cell and collect the electrical current. The metallic elements used as bipolar plates, end plates, and interconnectors in acid electrolyte and gaseous fuel cells are severely damaged by a combination of oxidation (due in particular to the use of oxygen, whether pure or contained in the air) and corrosion (due in particular to acid effluents from the electrolyte). This degradation rapidly leads to the loss of the electrical conductivity of the metallic elements and today requires the use of very specific alloys, possibly coated with pure gold. The solution investigated in the present study is the use of a protective coating based on single-phase nitrides obtained by reactive magnetron sputtering or reactive HiPIMS (High-Power Impulse Magnetron Sputtering). The influence of the microstructure on the physical–chemical properties was studied. The electrochemical properties were quantified following two approaches. First, the corrosion current of the developed coatings was measured at room temperature and at higher temperatures using the Linear Sweep Voltammetry (LSV) technique. Then, Electrochemical Impedance Spectroscopy (EIS) measurements were performed to better identify and evaluate their corrosion-resistance performances.

Photoelectrochemical response of tin iodide phosphide (SnIP) composites with MoSe2, MoS2, and h‐BN

For a future world fuelled by green energy it is invaluable to develop, test and maximise the catalytic efficiency of new effective water‐splitting materials. In this paper, we further explore the catalytic activity of double‐helical tin iodide phosphide (SnIP), as it features bandgaps in the ideal region for this process. We found that its photoelectrochemical response can be multiplied by forming composites of SnIP with selected 2D materials, focusing on hexagonal boron nitride and the transition metal dichalcogenides (TMDs) MoSe2 and MoS2. These nanocomposites were analysed with Powder‐X‐ray diffraction (P‐XRD), Raman, and UV/VIS bandgap determination. Their photo activity was assessed under simulated solar light through chrono amperometry and linear sweep voltammetry (CA, LSV). The high anisotropy of the involved materials enables efficient charge separation at the 1D/2D interfaces, increasing photoelectrochemical response four‐fold.

Cellulose acetate-based polymer electrolyte for energy storage application with the influence of BaTiO3 nanofillers on the electrochemical properties: A progression in biopolymer-EDLC technology

The bio-based solid polymer electrolyte serves as a promising choice for the next generation of energy storage devices to meet the requirement of green chemistry. In the current research, a green plasticized magnesium ion-conducting biopolymer electrolyte was developed using simple solution casting method for Electric Double Layer Capacitors (EDLC) applications. The biopolymer Cellulose Acetate (CA) as the host polymer, with varying concentrations of BaTiO3 as the nanofiller, Mg(CF3SO3)2 as the ionic dopant, and PEG as the plasticizer. A 2 wt% addition of BaTiO3 to the biopolymer electrolyte exhibits maximum conductivity measuring 2.4 × 10−3 S/cm. Linear Sweep Voltammetry (LSV) analysis demonstrates maximum stability voltage of 3.51 V. The ionic transference number (tion) and (tMg2+) were determined to be 0.99 and 0.41 respectively. The fabricated EDLC device with the same electrolyte showed polarisation curve without any noticeable peaks in the Cyclic Voltammetry (CV) plot, indicating no redox reactions occurring at the electrode-electrolyte interface. Galvanostatic Charge Discharge (GCD) results showed excellent coulombic efficiency, stability and Energy Density and Power Density performance over 2000 cycles. The incorporation of BaTiO3 into biopolymer membranes presents a viable approach towards sustainable energy storage solutions by enhancing the energy storage capacity of EDLC devices.

Vertically growth of MoS2 nanosheets on g-C3N4 towards enhanced electrocatalytic performance

MoS2 nanosheets were vertically grown in S-doped graphitic carbon nitride (g-C3N4) nanosheets to enhance electrochemical performance. Dicyandiamide was used as a precursor while sodium molybdate and thioacetamide were as additives, and sulfur was introduced into the carbon lattice of thin-layered g-C3N4 by a two-step thermal polymerization. S-g-C3N4/MoS2 (SCN/MoS2) heterojunctions were then created by a solvothermal synthesis. Subsequently, the electrochemical performance of the heterojunctions was explored. The result suggested that the surface of S-g-C3N4 nanosheets load on uniformly arranged layered MoS2 possession revealed the smallest Tafel slope of 77.2 mV dec−1. After 1000 cycles, no significant change was observed for the linear sweep voltammetry curves. The SCN/MoS2 heterojunction revealed a specific capacity of 588 F g−1 after being assembled into an asymmetric supercapacitor. Superior thin g-C3N4 nanosheets and constituting a composite with strong interfacial electronic coupling with MoS2, doping with heteroatomic elements, and changing the surface structure of g-C3N4 enhanced the charge transfer kinetics and improved the electrochemical performance.

Bioinspired synthesis of ZrO2‐Zr3Er4O12‐based mixed nanomaterial; characterization and analyzing its potential as an electrode material in energy‐based devices and its electrocatalytic property

AbstractThe sustainable and ecofriendly synthesis of transition metal oxide‐based nanomaterials has always been a matter of concern. In this study, a bioinspired synthesis route was adopted to synthesize ZrO2‐Zr3Er4O12‐based mixed nanomaterial using leaf extract of medicinal plant Amaranthus viridis as reducing and stabilizing agent in replacement of the obnoxious chemicals which are a great threat to the sustainable environment. The synthesized material revealed the spherical shaped morphology through scanning electron microscopy, whereas crystal size of 15.7 nm was observed through Xray‐diffraction, and band gap value of 2.7 eV was acquired using Tauc plot. Newly synthesized ZrO2‐Zr3Er4O12 nanocomposite was then investigated for its role as electrocatalyst in a generation of energy through the hydrogen evolution reaction and oxygen evolution reaction. The ZrO2‐Zr3Er4O12‐based electrocatalyst showed better potential for hydrogen evolution reaction measurements with the overpotential value of 242 mV. Furthermore, the notable capacitance value of 495.6 F/g was obtained through cyclic voltammetry for energy storage studies. The cyclic stability was also analyzed using linear sweep voltammetry and results showed promising stability for 2000 cycles. Consequently, the green and economical synthesis route as well as promising electrochemical behavior of ZrO2‐Zr3Er4O12‐based electrode make it feasible choice for large scale application.

Low-Cost, Safe, and Anion-Flexible Method for the Electrosynthesis of Diaryliodonium Salts.

An electrochemical approach toward the synthesis of diaryliodonium salts based on anodic C-I coupling between aryl iodides and arenes is presented. In contrast to previous protocols, our method requires no chemical oxidants, strong acids, or fluorinated solvents. A further advantage is that by use of the appropriate supporting electrolyte, the counterion of choice can be introduced, which is time- and cost-saving as compared to postsynthesis ion exchange. This "anion-flexibility" is particularly interesting when considering the pronounced effect of the counterion on the reactivity of diaryliodonium species in aryl transfer reactions. The scope of our method comprises 24 examples with isolated yields of up to 99%. Scalability was demonstrated by the synthesis on a gram scale. Furthermore, it was shown that the diaryliodonium-containing post-electrolysis solution can be used without further workup as a reactive medium for O-arylation reactions. Finally, a series of para-substituted diaryliodonium compounds was studied using linear sweep voltammetry on a microelectrode and analyzed with respect to the influence of the electronic structure on the redox behavior.

Revealing the intricacies of natural convection: A key factor in aqueous zinc battery design

Aqueous zinc-based batteries offer high safety, abundant resources, low cost, and environmental friendliness, making them a promising alternative to lithium-ion batteries for large-scale energy storage markets. However, the natural convection in the electrolyte during operation, which can greatly affect the battery performance, is overlooked for a long time. Through particle tracing experiments, this study demonstrates that in the vertical placement of the battery, natural convection occurs due to the variation of electrolyte density, whereas it does not happen when the cathode is on top. Besides, there is a significant difference in electrochemical performance between these two configurations, with a voltage difference of up to 0.25 V at 10 mA cm⁻² and a peak current difference of up to 3.4 mA in linear sweep voltammetry. Simulation results show that convective mass transfer can be up to 100 times greater than diffusive mass transfer in a bulk solution. This highlights the importance of considering natural convection to improve model accuracy. Further, to increase energy density, batteries are scaled up in practical applications to reduce the weight of the casing. This work simulates mass transfer conditions under various scenarios, illustrating the trade-off between current density and battery size, and offering new guidance for the design of aqueous zinc-based batteries.

Biochar rich in amino ligand for copper selective recollection in wastewater

The coexistence with other similar valence counterparts greatly hinders the selective recovery of metals, resulting in serious resource waste and environmental pollution. Herein, biochar with numerous surface –NO2 and –COOH groups was prepared, and in-situ ammonization reaction was catalyzed by electricity to transform those attached –NO2 into –NH2. The as-obtained biochar with stable ligand of –NH2 (BC-NH2) exhibited an excellent selective adsorption efficiency for copper. Among six bi-valence ions of copper, lead, cadmium, zinc, magnesium and calcium, the above adsorbent could selective recollect 88.76 % and 73.61 % of copper from aqueous and soil respectively. More importantly, the other existent bi-valence ions can be effectively substituted by Cu(II) with a high efficiency up to 91.92 %, even they were saturated on the BC-NH2. The Linear sweep voltammetry curves (LSV) and density functional theory (DFT) demonstrate the strongest affinity between Cu(II) and BC-NH2 than that of other heavy metals, indicating the keynote of the selective mechanism should be the formation of ultra-stable complex between –NH2 and copper ions. Besides, –COOH group participate the pathway for the transformation from –NO2 to –NH2. This study provides a new concept, and an ideal material as well as novel preparing stratagem, for selective recollecting copper through chelating.

Water oxidation through electrocatalytic process using cobalt and nickel complexes of thiazole Schiff-base ligands

Ni(OAc)2.4H2O and CoCl2.6H2O reacted with thiazole ligands, HL and HL' (where HL= (E)-2-(((4-phenylthiazol-2-yl)imino)methyl)phenol and HL'= (Z)-2-(2-benzylidenehydrazinyl)-4-phenylthiazole, in ethanol to create new mononuclear Co(II) and Ni(II) complexes, CoL2, NiL2, CoL'2, and NiL'2 (1-4). X-ray diffraction analysis, spectroscopic, and electrochemical methods were used to study the complexes. A carbon paste electrode that had been modified by complexes 1-4 was used as the working electrode in a three-electrode setup to test the complexes' ability in water oxidation reaction at pH 13. The linear sweep voltammetry (LSV) curves showed that complexes 3 and 2 have much greater activity and only require the overpotential of 570 and 690 mV ʋs. RHE at a current density of 10 mA/cm2 with Tafel slopes of 86.92 and 94.19 mVdec−1 respectively in an alkaline solution. In addition, the amperometry tests exhibited brilliant stability for water oxidation by CPE-complex 3 and CPE-complex 2 under electrochemical conditions at pH 13. Although X-ray diffraction patterns did not display a crystalline structure, the scanning electron microscopy images displayed that cobalt oxide and nickel oxide in an alkaline condition are proper catalysts for water oxidation reaction on the surface of the modified electrode.

Bio-derived gel polymer electrolytes from zein and honey blends integrated with ammonium nitrate for electrical double layer capacitors

Although electrical double layer capacitors (EDLCs) are known to exhibit impressive power density, rapid charging/discharging, and long cycle life, their energy density remains a hurdle for broader use. Gel polymer electrolytes (GPEs) offer an interesting approach to improve the energy density of EDLCs while maintaining their other desirable characteristics. This study investigates the development of novel GPEs based on zein, honey, and ammonium nitrate (NH4NO3) for EDLC applications. The GPEs are prepared by incorporating zein, honey, and NH4NO3 in a dimethyl sulfoxide (DMSO) solvent system through a solution casting method. The degree of crystallinity of zein successfully reduced from 33.0 % to 15.71 % with the addition of 20 wt% NH4NO3. The interaction between zein, honey and NH4NO3 is confirmed by observing the shifting of the hydroxyl band. The ambient ionic conductivity of zein-honey increases from (4.86 ± 0.36) × 10−4 S cm−1 to (4.19 ± 0.40) × 10−3 S cm−1 with the incorporation of 20 wt% NH4NO3 (ZH20), exhibiting the significantly lowest Tg value (77.53 °C). Linear sweep voltammetry (LSV) demonstrates high electrochemical stability up to 2.6 V of ZH20. Additionally, the transference number (tion) of 0.989 indicates a dominant role of ionic charge carriers in this work. Finally, the ZH20-based GPE is used as both an electrolyte and separator to fabricate EDLC. Its electrochemical behavior has demonstrated stable results in terms of specific capacitance, energy, and power density, with fast rate performance observed through cyclic voltammetry and galvanostatic charge-discharge techniques.