Corrosion inhibition of carbon steel immersed in a 1 M HCl solution using benzothiazole derivatives

Corrosion inhibition effect of 2-mercaptobenzothiazole (MBT) and 2-aminobenzothiazole (ABT) compounds on ST-37 carbon steel in 1 M hydrochloric acid solution was investigated by electrochemical impedance spectroscopy (EIS), and it was observed that both of these compounds have corrosion inhibition effect on carbon steel. Evaluation of electrochemical behavior in test solutions showed that by increasing the immersion time from 15 to 300 min, corrosion resistance of samples is increased and at the same immersion time MBT has a better corrosion inhibition in comparison to ABT. AFM technique was performed for MBT and ABT. The results of calculations showed superior inhibition efficiency of MBT in comparison to ABT. This can cause easier protonation and consequently adsorption on the metal surface occurs.     

Electrochemical fabrication of novel fluorescent polymeric film: Poly(pyrrole–pyrene)

We describe herein the electrochemical characterization and polymerization of 4-pyren-1-yl-butyric acid 11-pyrrol-1-yl-decyl ester (pyrrole–pyrene) in CH₃CN. The electrochemical oxidation of the pyrrole group at 0.77 V vs Ag/Ag + 10 mM in CH₃CN led to the first example of a fluorescent polypyrrole film. The mechanism of deposition on platinum electrode was studied by voltammetry and chronoamperometry. The optical properties of the polymeric films electrogenerated on ITO electrodes were examined by UV–visible spectroscopy and fluorescence microscopy indicating an increase in fluorescence properties by increased polymer thickness. The electrochemical oxidation of pyrenyl group linked to the polypyrrole backbone was carried out at 1.2 V. This additional polymerization was demonstrated by UV–visible spectroscopy and induced the loss of the fluorescence properties of the resulting polymeric film.     

Corrosion behaviour of an Mg–Y–RE alloy used in biomedical applications studied by electrochemical techniques

Magnesium, due to its biocompatibility, a necessity in metabolic processes, and better mechanical properties than polymer, is an ideal candidate for biodegradable implants. The main actual limitation for the use of magnesium alloys is its too fast degradation rate in the physiological environment. The corrosion behaviour of an Mg–Y–RE magnesium alloy in two different physiological solutions (artificial plasma (AP) and simulated body fluid (SBF)) was investigated, using electrochemical impedance spectroscopy (EIS).The investigation showed that SBF is significantly more aggressive than AP with regard to the polished surface. A large difference in the corrosion rate and mechanisms (uniform or localized corrosion) is observed as a function of the buffer capacity of the media, but also of the carbonate and chloride content. For temporary surface protection, the formation of an approximately 350–400 nm dense hydroxide layer is obtained by electrochemical anodising. An increase of the corrosion resistance of the treated alloy for both physiological solutions is obtained, and this is especially noticeable for a long immersion time in AP.     

A Raman spectroscopy study of cerium oxide in a cerium–5 wt.% lanthanum alloy

This paper describes a study of a cerium–5 wt.% lanthanum (Ce–5 wt.% La) alloy using Raman spectroscopy and X-ray diffraction (XRD). Examination of the alloy microstructure by optical microscopy and Raman spectroscopy revealed the presence of inclusions which were identified as cerium oxide (CeO₂). The study also highlighted the need to avoid excessive laser power during acquisition of the Raman spectra as this appeared to cause the oxidation of the region being analysed where previously no cerium oxide peak had been detected. The propensity of cerium to oxidise in air results in the formation of a CeO₂ layer on the surface of the alloy. Raman spectroscopy of the oxide layer formed on the alloy after exposure to air for 21 days found that the Raman peak denoting cerium oxide was seen at between 5 and 7 cm⁻¹ lower than the value for CeO₂ (465 cm⁻¹). This is attributed to a combination of a sub-stoichiometric oxide layer and the presence of La in the alloy.     

Polyvinyl alcohol–sulphanilic acid water soluble composite as corrosion inhibitor for mild steel in hydrochloric acid medium

The inhibitive action of synthesised polyvinyl alcohol–sulphanilic acid (PVASA) composite on the corrosion of commercial mild steel in 1 M HCl medium has been investigated by weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopic (EIS) methods. Characterization of PVASA composite has been carried out using Fourier transform infrared spectroscopy (FTIR). Experimental results reveal that PVASA composite acts as an inhibitor in the acid environment. The inhibition efficiency increases with an increase in the concentration of the inhibitor. Maximum inhibition efficiency of PVASA composite was found to be 84% at 6000 ppm. Thermodynamic and kinetic parameters have been obtained from temperature studies. Electrochemical measurement reveals that PVASA composite acts as a mixed inhibitor and the adsorption follows Langmuir adsorption isotherm.     

Electrodeposition of highly alloyed quaternary PtPdRuOs catalyst with highly ordered nanostructure

Introducing palladium to traditional platinum-based alloy electrocatalysts offers a novel approach to develop highly efficient anode electrocatalysts for direct methanol fuel cells. In this communication, we report the preparation of thin-wall mesoporous quaternary PtPdRuOs alloy catalyst via electrochemical co-reduction of their chloride precursors all dissolved in aqueous domains of the liquid crystalline phases of an oligoethylene oxide surfactant. Scanning electron micrographs (SEM) reveal that the deposit is composed of uniform nanospheres with an average diameter of around 120 nm and the average mole composition of the metal elements is Pt₃₇Pd₃₃Ru₂₂Os₁₀. Transmission electron micrographs (TEM) disclose that the nanospheres have an ordered nanostructure which is characterized by periodic pores of 3.6 ± 0.4 nm in diameter separated by walls of 2.4 ± 0.4 nm in thickness. X-ray diffraction studies signal a highly alloying degree for the four metal components in the deposit. The specific electrochemical surface area of the nanostructured powder assessed using underpotential deposited Cu stripping technique is as high as 105 m² g^–1, much higher than that of unsupported precious metal catalysts prepared using standard techniques. These characters suggest that the quaternary PtPdRuOs alloy materials with high surface area and thin-wall mesoporous structure would be a novel class of promising electrocatalysts for direct methanol fuel cells.     

On the corrosion inhibition of iron in hydrochloric acid solutions,Part I: Electrochemical DC and AC studies

The inhibitive action of 4-methyl pyrazole (4MP) against the corrosion of iron (99.9999%) in solutions of hydrochloric acid has been studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). At inhibitor concentration range (10^?3–10^?2 M) in 1.0 M acid, the results showed that 4MP suppressed mainly the anodic processes of iron corrosion in 1.0 M HCl by adsorption on the iron surface according to Temkin adsorption isotherm. Both potentiodynamic and EIS measurements reveal that 4MP inhibits the iron corrosion in 1.0 M HCl and that the efficiency increases with increasing inhibitor concentration. Data obtained from EIS were analyzed to model the corrosion inhibition process through an equivalent circuit.     

Electrochemical and FTIR spectroscopic study of CO2 reduction at a nanostructured Cu/reduced graphene oxide thin film

Here we report a facile approach to synthesize a novel nanostructured thin film comprising Cu nanoparticles (NPs) and reduced graphene oxide (rGO) on a glassy carbon electrode (GCE) via the direct electrochemical reduction of a mixture of cupper and graphene oxide (GO) precursors. The effect of the applied potential on the electrochemical reduction of CO₂ was investigated using linear sweep voltammetric (LSV) and chronoamperometric (CA) techniques. Carbon monoxide and formate were found as the main products based on our GC and HPLC analysis. The electrochemical reduction of CO₂ at the Cu/rGO thin film was further studied using in situ ATR-FTIR spectroscopy to identify the liquid product formed at different applied cathodic potentials. Our experimental measurements have shown that the nanostructured Cu/rGO thin film exhibits an excellent stability and superb catalytic activity for the electrochemical reduction of CO₂ in an aqueous solution with a high current efficiency of 69.4% at − 0.6 V vs. RHE, promising for the efficient electrochemical conversion of CO₂ to valuable products.     

A study on solution deposited CuSCN thin films: Structural,electrochemical, optical properties

A cost-effective successive ionic layer adsorption and reaction (SILAR) method was used to deposit copper (I) thiocyanate (CuSCN) thin films on glass and steel substrates for this study. The deposited thin films were characterized for their structural, morphological, optical and electrochemical properties using X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible spectroscopy and VersaSTAT potentiostat. A direct band gap of 3.88 eV and 3.6 eV with film thickness of 0.7 μm and 0.9 μm was obtained at 20 and 30 deposition cycles respectively. The band gap, microstrain, dislocation density and crystal size were observed to be thickness dependent. The specific capacitance of the CuSCN thin film electrode at 20 mV/s was 760 F g⁻¹ for deposition 20 cycles and 729 F g⁻¹ for deposition 30 cycles.     

Corrosion resistance of electroless Cu–P and Cu–P–SiC composite coatings in 3.5% NaCl

The Cu–P and Cu–P–SiC composite coatings on carbon steel substrates were deposited via electroless plating. The anti-corrosion properties of Cu–P and Cu–P–SiC coatings were studied in 3.5% NaCl solution. The anti-corrosion properties of Cu–P and Cu–P–SiC coatings were investigated in 3.5% NaCl solution by the weight loss, potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) techniques. It has been found that the shift in the corrosion potential (E_corr) towards the noble direction, decrease in the corrosion current density (I_corr), increase in the charge transfer resistance (R_ct) and decrease in the double layer capacitance (C_dl) values indicated an improvement in corrosion resistance with the incorporation of SiC particles in the Cu–P matrix. The effects of varying the SiC concentration on the corrosion resistance of carbon steel were investigated and it was found that the best anti-corrosion property of Cu–P–SiC is at 5 g L^?1 SiC in the bath formulation.     

A high performance nano-structure conductive coating on a Crofer22APU alloy fabricated by a novel spinel powder reduction coating technique

A nano-structure conductive coating was fabricated on a Crofer22APU alloy interconnect by an original coating strategy using Mn_0.9Y_0.1Co₂O₄ (MYC) novel spinel nanocrystalline powder. A unique treatment method by which the spinel powder was reduced was used to prepare the green coating. The resulting coating was about 12 μm in thickness, and was composed of MYC nanocrystalline with an average particle size of about 100 nm. The coating was well adhered with the substrate alloy. Less than 4 mΩ cm² of the area specific resistance (ASR) was obtained, and no obvious degradation was observed for a coated alloy (whose coating thickness was about 30 μm) after operated at 800 °C for 538 h under seven thermal cyclings. The coated alloy exhibited excellently electrical performance and long-term stability compared with the uncoated one. The exploration of the novel spinel powder reduction coating technique for alloy interconnect to obtain cheap coatings with excellent microstructure and performance showed a promising prospect for the practical application of solid oxide fuel cells (SOFCs).     

Electrochemical and XPS studies of a Nb-containing Ti-based glass-forming alloy system in H2SO4 solution

The corrosion behaviors of Ti₄₀Zr₂₅Ni_12 -xNb_xCu₃Be₂₀ (x = 0, 4, 8, and 12 at.%) alloys in 0.5 mol/L H₂SO₄ solution were studied, aiming to establish the relationship between Nb content and corrosion resistance. The addition of Nb element gives rise to a clear microstructural evolution, from a completely amorphous structure for the alloys without Nb and with 4% Nb alloys to an amorphous/crystalline composite structure for the alloys with 8% and 12% Nb. The alloy with higher Nb content exhibits better corrosion resistance, which can be attributed to the formation of Ti^4 +-, Zr^4 +-, and Nb^5 +-enriched highly protective surface film in corrosive solutions.     

Active protective Al–Ce alloy coating electrodeposited from ionic liquid

The electrochemical co-deposition of Al–Ce metallic protective coating with active inhibiting effect was performed for the first time using an ionic liquid as an electrolyte. Cerium was successfully co-deposited with aluminium on surface of Pt and AA2024 aluminium alloy forming uniform films with globular micro-structure and thickness up to 75 μm.Cerium was introduced into the aluminium coating as a potential corrosion inhibitor which can be liberated during sacrificial dissolution of the galvanic layer deposited on the alloy surface. The released inhibitor provides an additional active corrosion protection slowing down the corrosion processes in the defects.     

Li/LiFePO4 batteries with room temperature ionic liquid as electrolyte

Room temperature ionic liquid (RTIL) was prepared on basis of N-methyl-N-butylpiperidinium bis(trifluoromethanesulfonyl)imide (PP₁₄TFSI), which showed a wide electrochemical window (?0.1–5.2 V vs. Li⁺/Li) and is theoretically feasible as an electrolyte for batteries with metallic Li as anodes. The addition of vinylene carbonate (VC) improved the compatibility of PP₁₄TFSI-based electrolyte towards lithium anodes and enhanced the formation of solid electrolyte interphase film to protect lithium anodes from corrosion. Accordingly, Li/LiFePO₄ cells initially delivered a discharge capacity of about 127 mAh g^?1 at a current density of 17 mA g^?1 in the ionic liquid with the addition of VC and showed better cyclability than in the neat ionic liquid. Electrochemical impedance spectroscopy disclosed that the addition of VC enhanced Li-ion diffusion and depressed interfacial resistance significantly.     

Surface plasmon resonance and electrochemistry for detection of small molecules using catalyzed deposition of metal ions on gold substrate

Small molecules are difficult to detect by conventional surface plasmon resonance (SPR) spectroscopy due to the fact that the changes in the refractive index resulted from the binding process of small biomolecules are quite small. Here, we report a simple and effective method to detect small biomolecule using SPR spectroscopy and electrochemistry by catalyzed deposition of metal ions on SPR gold film. As an example, the ascorbic acid-mediated deposition of Ag on gold film was monitored by in situ SPR spectrum. The deposition of Ag atom on gold film resulted in an obvious decrease of depth in SPR angular scan curves of reflectance intensity and minimum reflectivity angle. The depth change of the SPR reflectance intensity and minimum reflectivity angle curves mainly relied on the amount of Ag atom deposited on gold film that can be controlled by the concentration of ascorbic acid. By monitoring the deposition of Ag atom on gold film, ascorbic acid was detected in the concentration range of 2 × 10⁻⁵ M to 1 ×  10⁻³ M. After each of detections, the SPR sensor surface was completely regenerated by a potential step that stripped off the Ag atom. Furthermore, the regeneration process of the sensor surface provides the feasibility for detecting the concentration of ascorbic acid by electrochemical method.     

Electrodeposition of aluminum on magnesium alloy in aluminum chloride (AlCl3)–1-ethyl-3-methylimidazolium chloride (EMIC) ionic liquid and its corrosion behavior

A dense and adhesive Al layer was successfully electrodeposited on a Mg alloy in aluminum chloride–1-ethyl-3-methylimidazolium chloride ionic liquid. The corrosion resistance of the uncoated and Al-coated samples was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization measurements in 3.5 wt% NaCl solution. It was confirmed that the protective Al layer significantly reduces the corrosion rate of the Mg alloy. However, the deposition potential was a crucial factor that governed the structure and therefore the protection capability of the Al layer.     

A combined computational & electrochemical exploration of the Ammi visnaga L. extract as a green corrosion inhibitor for carbon steel in HCl solution

Natural-based corrosion inhibitors have gained great research interest thanks to their low cost and higher performance. In this work, the chemical composition of the methanolic extract of Ammi visnaga umbels (AVU) was evaluated by gas chromatography (GC) coupled with mass spectrometry (MS) and applied for corrosion inhibition of carbon steel (CS) in 1.0 mol/L HCl using chemical and electrochemical techniques along with scanning electron microscope (SEM) and theoretical calculations. A total of 46 compounds were identified, representing 89.89% of the overall chemical composition of AVU extract, including Edulisin III (72.88%), Binapacryl (4.32%), Khellin (1.97%), and Visnagin (1.65%). Chemical (Weight loss) and electrochemical (potentiodynamic polarization curves (PPC), and electrochemical impedance spectroscopy (EIS)) techniques revealed that investigated extract can be used as an effective corrosion inhibitor for carbon steel in 1.0 mol/L HCl solution. At a low dose of 700 ppm, the inhibitory action of AVU extract reached an inhibition efficiency of 84 percent. According to polarization tests, the investigated extract worked as a mixed inhibitor, protecting cathodic and anodic corrosion reactions. The EIS test showed that upon the addition of AVU extract to HCl solution, the polarization resistance increased while the double layer decreased. SEM images showed a protected CS surface in the inhibited solution. Quantum chemical calculations by Density Functional Theory (DFT) for the main components confirmed the major role of heteroatoms and aromatic rings as adsorption sites. Molecular dynamics (MD) simulation was used to study the adsorption configuration of the main components on the Fe(1 1 0) surface. Outcomes from this study further confirmed the significant advantage of using plant-based corrosion inhibitors for protecting metals and alloys.     

DNA surface nanopatterning by selective reductive desorption from polycrystalline gold electrode

Selective electrochemical desorption was employed to pattern polycrystalline gold electrodes with thiolated DNA. The sacrificial thiol 3-mercaptopropionic acid (3-MPA) was selectively desorbed from the crystallographic plane Au(1 1 1) to revealed bare gold domains, surrounded by SAMs of 3-MPA present on the adjacent low index planes Au(1 1 0) and Au(1 0 0). Thiolated DNA sequences were further immobilised on the revealed Au(1 1 1) and the hybridisation efficiency towards complementary and non-complementary sequences evaluated. All derivatisation steps were followed by cyclic voltammetry and faradaic electrochemical impedance spectroscopy. Successful hybridisation resulted in large drops in resistance to charge transfer, attributed to the extension of the DNA surface duplex into solution resulting in an increased diffusion of electrochemical probes to the electrode surface. The results demonstrated the feasibility of the method to generate a DNA sensor able to efficiently discriminate between complementary and non-complementary sequences with good reproducibility.     

Impact of reforming catalyst on the anodic polarisation resistance in single-chamber SOFC fed by methane

This paper emphasises the electrochemical and catalytic properties of a Ni–10% GDC (10% gadolinium-doped ceria) cermet anode of a single-chamber solid oxide fuel cell (SC-SOFC). Innovative coupling of electrochemical impedance spectroscopy with gas chromatography measurements was carried out to characterise the anode material using an operando approach. The experiments were conducted in a symmetric anode/electrolyte/anode cell prepared by slurry coating resulting in 100 μm-thick anode layers. The electrochemical performance was assessed using a two-electrode arrangement between 400 °C and 650 °C, in a methane-rich atmosphere containing CH₄, O₂ and H₂O in a 14:2:6 volumetric ratio. The insertion of a Pt–CeO₂ based catalyst with high specific surface area inside the cermet layer was found to promote hydrogen production from the Water Gas Shift reaction and consequently to improve the electrochemical performances. Indeed, a promising polarisation resistance value of 12 Ω cm² was achieved at 600 °C with a catalytic loading of only 15 wt.%.     

Hierarchically ordered porous nickel oxide array film with enhanced electrochemical properties for lithium ion batteries

Hierarchically ordered porous nickel oxide array film was prepared by electrodeposition through monolayer polystyrene spheres template. The as-prepared film had a highly porous structure of interconnected macrobowls array possessing nanopores. As anode material for lithium ion batteries, the porous array NiO film exhibited weaker polarization, higher coulombic efficiency and better cycling performance in comparison with the dense NiO film. After 50 cycles, the discharge capacity of porous array NiO film was 518 mAh g^? 1 at 1 C rate, higher than that of the dense NiO film (287 mAh g^? 1). The enhancement of the electrochemical properties was due to the unique hierarchical porous architecture, which provided fast ion/electron transfer and alleviated the structure degradation during the cycling process.