Systematic DFT studies of CO-Tolerance and CO oxidation on Cu-doped Ni surfaces

High-performance spinel NiMn2O4 supported carbon felt for effective electrochemical conversion of ethylene glycol and hydrogen evolution applications

One of the most effective electrocatalysts for electrochemical oxidation reactions is NiMn2O4 spinel oxide. Here, a 3-D porous substrate with good conductivity called carbon felt (CF) is utilized. The composite of NiMn2O4-supported carbon felt was prepared using the facile hydrothermal method. The prepared electrode was characterized by various surface and bulk analyses like powder X-ray diffraction, X-ray photon spectroscopy (XPS), Scanning and transmitted electron microscopy, thermal analysis (DTA), energy dispersive X-ray (EDX), and Brunauer-Emmett-Teller (BET). The activity of NiMn2O4 toward the electrochemical conversion of ethylene glycol at a wide range of concentrations was investigated. The electrode showed a current density of 24 mA cm-2 at a potential of 0.5 V (vs. Ag/AgCl). Furthermore, the ability of the electrode toward hydrogen evaluation in an alkaline medium was performed. Thus, the electrode achieved a current density equal 10 mA cm-2 at an overpotential of 210 mV (vs. RHE), and the provided Tafel slope was 98 mV dec-1.

Interfacial engineering of nickel selenide with CeO2 on N-doped carbon nanosheets for efficient methanol and urea electro-oxidation

The design of low cost, high efficiency electrocatalysts for methanol oxidation reactions (MOR) and urea oxidation reactions (UOR) is a pressing need to address the energy crisis and water pollution. In the present work, we developed Cerium dioxide (CeO2) and nickel selenide (Ni0.85Se) nanoparticles integrated into three-dimensional N-doped carbon nanosheets to be used as efficient and stable bifunctional electrocatalysts for MOR and UOR. By optimizing the selenization temperature, the CeO2-modified Ni0.85Se obtained at selenization temperature of 550 °C (CeO2-Ni0.85Se-550-NC) has the best MOR and UOR electrochemical performance. The CeO2-Ni0.85Se-550-NC potential only requires 1.309 V (MOR) and 1.294 V (UOR) to reach 10 mA cm-2, respectively. The DFT study reveals that CeO2-Ni0.85Se-550-NC has the best reaction path with the synergistic effect between CeO2 and Ni0.85Se. The outstanding catalytic performance of CeO2-Ni0.85Se-550-NC may be due to the cointeraction between CeO2 and Ni0.85Se, allowing more defects that function as catalytic sites while promoting fast electron transfer in the N-doped carbon substrate.

Green Synthesis of NiFe2O4 Nano-Spinel Oxide-Decorated Carbon Nanotubes for Efficient Capacitive Performance-Effect of Electrolyte Concentration

Energy storage applications received great attention due to environmental aspects. A green method was used to prepare a composite of nickel-iron-based spinel oxide nanoparticle@CNT. The prepared materials were characterized by different analytical methods like X-ray diffraction, X-ray photon spectroscopy (XPS), scanning electron microscopy (SEM), and transmitted electron microscopy (TEM). The synergistic effect between nickel-iron oxide and carbon nanotubes was characterized using different electrochemical methods like cyclic voltammetry (CV), galvanostatic charging/discharging (GCD), and electrochemical impedance spectroscopy (EIS). The capacitances of the pristine NiFe2O4 and NiFe2O4@CNT were studied in different electrolyte concentrations. The effect of OH- concentrations was studied for modified and non-modified surfaces. Furthermore, the specific capacitance was estimated for pristine and modified NiFe2O4 at a wide current range (5 to 17 A g-1). Thus, the durability of different surfaces after 2000 cycles was studied, and the capacitance retention was estimated as 78.8 and 90.1% for pristine and modified NiFe2O4. On the other hand, the capacitance rate capability was observed as 65.1% (5 to 17 A g-1) and 62.4% (5 to 17 A g-1) for NiFe2O4 and NiFe2O4@CNT electrodes.

Synthesis and characterization of lead-based metal-organic framework nano-needles for effective water splitting application

Metal organic frameworks (MOFs) are a class of porous materials characterized by robust linkages between organic ligands and metal ions. Metal-organic frameworks (MOFs) exhibit significant characteristics such as high porosity, extensive surface area, and exceptional chemical stability, provided the constituent components are meticulously selected. A metal-organic framework (MOF) containing lead and ligands derived from 4-aminobenzoic acid and 2-carboxybenzaldehyde has been synthesized using the sonochemical methodology. The crystals produced were subjected to various analytical techniques such as Fourier-transform infrared spectroscopy (FT-IR), Powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Brunauer-Emmett-Teller (BET), and thermal analysis. The BET analysis yielded results indicating a surface area was found to be 1304.27 m2 g-1. The total pore volume was estimated as 2.13 cm3 g-1 with an average pore size of 4.61 nm., rendering them highly advantageous for a diverse range of practical applications. The activity of the modified Pb-MOF electrode was employed toward water-splitting applications. The electrode reached the current density of 50 mA cm-2 at an overpotential of - 0.6 V (vs. RHE) for hydrogen evolution, and 50 mA cm-2 at an overpotential of 1.7 V (vs. RHE) for oxygen evolution.

Chitosan Supports Boosting NiCo2O4 for Catalyzed Urea Electrochemical Removal Application

Currently, wastewater containing high urea levels poses a significant risk to human health. Else, electrocatalytic methodologies have the potential to transform urea present in urea-rich wastewater into hydrogen, thereby contributing towards environmental conservation and facilitating the production of sustainable energy. The characterization of the NiCo2O4@chitosan catalyst was performed by various analytical techniques, including scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Furthermore, the activity of electrodes toward urea removal was investigated by several electrochemical techniques. As a function of current density, the performance of the modified NiCo2O4@chitosan surface was employed to remove urea using electrochemical oxidation. Consequently, the current density measurement was 43 mA cm-2 in a solution of 1.0 M urea and 1.0 M KOH. Different kinetic characteristics were investigated, including charge transfer coefficient (α), Tafel slope (29 mV dec-1), diffusion coefficient (1.87 × 10-5 cm2 s-1), and surface coverage 4.29 × 10-9 mol cm-2. The electrode showed high stability whereas it lost 10.4% of its initial current after 5 h of urea oxidation.

Nafee S, Alamro FS, Pashameah RA, Ahmed HA, Medany SS. Zinc Nanocomposite Supported Chitosan for Nitrite Sensing and Hydrogen Evolution Applications

Nanoparticles of ZnO-Chitosan (Zn-Chit) composite were prepared using precipitation methods. Several analytical techniques, such as scanning electron microscope (SEM), transmitted electron microscope (TEM), powder X-ray diffraction (XRD), infrared spectroscopy (IR), and thermal analysis, were used to characterize the prepared composite. The activity of the modified composite was investigated for nitrite sensing and hydrogen production applications using various electrochemical techniques. A comparative study was performed for pristine ZnO and ZnO loaded on chitosan. The modified Zn-Chit has a linear range of detection 1–150 µM and a limit of detection (LOD) = 0.402 µM (response time ~3 s). The activity of the modified electrode was investigated in a real sample (milk). Furthermore, the anti-interference capability of the surface was utilized in the presence of several inorganic salts and organic additives. Additionally, Zn-Chit composite was employed as an efficient catalyst for hydrogen production in an acidic medium. Thus, the electrode showed long-term stability toward fuel production and enhanced energy security. The electrode reached a current density of 50 mA cm−2 at an overpotential equal to −0.31 and −0.2 V (vs. RHE) for GC/ZnO and GC/Zn-Chit, respectively. Electrode durability was studied for long-time constant potential chronoamperometry for 5 h. The electrodes lost 8% and 9% of the initial current for GC/ZnO and GC/Zn-Chit, respectively.

Nafee S, Alamro FS, Pashameah RA, Ahmed HA, Medany SS. Zinc Nanocomposite Supported Chitosan for Nitrite Sensing and Hydrogen Evolution Applications

Nanoparticles of ZnO-Chitosan (Zn-Chit) composite were prepared using precipitation methods. Several analytical techniques, such as scanning electron microscope (SEM), transmitted electron microscope (TEM), powder X-ray diffraction (XRD), infrared spectroscopy (IR), and thermal analysis, were used to characterize the prepared composite. The activity of the modified composite was investigated for nitrite sensing and hydrogen production applications using various electrochemical techniques. A comparative study was performed for pristine ZnO and ZnO loaded on chitosan. The modified Zn-Chit has a linear range of detection 1-150 µM and a limit of detection (LOD) = 0.402 µM (response time ~3 s). The activity of the modified electrode was investigated in a real sample (milk). Furthermore, the anti-interference capability of the surface was utilized in the presence of several inorganic salts and organic additives. Additionally, Zn-Chit composite was employed as an efficient catalyst for hydrogen production in an acidic medium. Thus, the electrode showed long-term stability toward fuel production and enhanced energy security. The electrode reached a current density of 50 mA cm-2 at an overpotential equal to -0.31 and -0.2 V (vs. RHE) for GC/ZnO and GC/Zn-Chit, respectively. Electrode durability was studied for long-time constant potential chronoamperometry for 5 h. The electrodes lost 8% and 9% of the initial current for GC/ZnO and GC/Zn-Chit, respectively.

Polyaniline-Supported Nickel Oxide Flower for Efficient Nitrite Electrochemical Detection in Water

A modified electrode with conducting polymer (Polyaniline) and NiO nanoflowers was prepared to detect nitrite ions in drinking water. A simple method was used to prepare the NiO nanoflower (NiOnF). Several techniques characterized the as-prepared NiOnF to determine the chemical structure and surface morphology of the NiO, such as XRD, XPS, FT-IR, and TGA. The activity of the electrode toward nitrite sensing was investigated over a wide range of pH (i.e., 2 to 10). The amperometry method was used to determine the linear detection range and limit. Accordingly, the modified electrode GC/PANI/NiOnf showed a linear range of detection at 0.1-1 µM and 1-500 µM. At the same time, the limit of detection (LOD) was 9.7 and 64 nM for low and high concentrations, respectively. Furthermore, the kinetic characteristics of nitrite, such as diffusion and transport coefficients, were investigated in various media. Moreover, the charge transfer resistance was utilized for nitrite electrooxidation in different pH values by the electrochemical impedance technique (EIS). The anti-interfering criteria of the modified surfaces were utilized in the existence of many interfering cations in water (e.g., K⁺, Na⁺, Cu²⁺, Zn²⁺, Ba²⁺, Ca²⁺, Cr²⁺, Cd²⁺, Pd²⁺). A real sample of the Nile River was spiked with nitrite to study the activity of the electrode in a real case sample (response time ~4 s). The interaction between nitrite ions and NiO{100} surface was studied using DFT calculations as a function of adsorption energy.

Experimental and theoretical studies for corrosion of molybdenum electrode using streptomycin drug in phosphoric acid medium

Corrosion inhibition of molybdenum electrode in H₃PO₄ acid medium of different concentrations (3.0 to 13 M) has been investigated utilizing different electrochemical techniques. It was observed that the most corrosive concentration is 3.0 M orthophosphoric acid concentration. The effect of adding Cl^- to 3.0 M orthophosphoric acid in the concentration range of 0.1 to 1.0 M was also studied. This study showed that the most corrosive medium is 3.0 M containing 1.0 M chloride ion with the greatest rate of hydrogen production. In 3.0 M H₃PO₄ acid with 1.0 M of NaCl, the tested electrode's corrosion and hydrogen production may be successfully suppressed by adding Streptomycin of 10 mM concentration leading to high inhibition efficiency. The outcomes of the studies were confirmed by scanning electron microscopic examination. Additionally, a computational chemistry approach was used to investigate how streptomycin adsorbs and inhibits corrosion at the interface of metal surfaces, and the outcomes of the computational studies are in excellent accord with the experimental findings.

High-performance IN738 superalloy derived from turbine blade waste for efficient ethanol, ethylene glycol, and urea electrooxidation

In this work, IN738 superalloy used previously in gas turbines was recycled and used as a working electrode for the electrooxidation of different fuels, namely ethylene glycol, ethanol, and urea. The electrocatalytic efficiency of the electrode was studied by cyclic voltammetry, chronoamperometry, and electrochemical impedance. Several kinetics parameters like diffusion coefficient, Tafel slope, rate constant, and activation energy were calculated. The modified electrode was characterized as received using XRD, SEM, and EDAX to elucidate the crystal structure and surface morphology before and after electrochemical oxidation. The anodic current densities of electrochemical oxidation of ethanol, ethylene glycol, and urea were 29, 17, and 12 mA.cm−2, respectively, in an alkaline solution at a potential of 0.6 V (vs. Ag/AgCl). The kinetic parameters like diffusion coefficients for ethanol, ethylene glycol, and urea were found to be 1.5 $$\times$$ × 10–6, 1.038 $$\times$$ × 10–6, and 0.64 $$\times$$ × 10–6 cm2 s−1, respectively. The charge transfer resistances were estimated for electrooxidation of different fuels by electrochemical impedance spectroscopy (EIS).

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