H2SO4 Solution Research Articles

Experimental and Computational Insights into the Effects of -NH2 and -Cl Functional Groups on the Copper Corrosion Inhibition by Benzotriazole

Abstract The influences of -NH2 and -Cl groups on the copper corrosion inhibition in 0.5 M H2SO4 solution by benzotriazole were studied using experimental methods and density functional theory calculations. Mass loss tests, potentiodynamic polarization, and surface morphology analyses revealed notable differences: while unmodified benzotriazole showed an inhibition efficiency of 76.6 %, the -Cl derivative increased this to 87.6 %, whereas the -NH2 derivative dropped it to 61.0 % at the concentration of 5×10-4 M. Density functional theory calculations indicated these differences are not due to electronic properties or inhibitor-copper interaction energies but rather to the inhibitor’s influence on the oxygen reduction reaction, especially O2 and H2O adsorption. The -NH2 group formed strong hydrogen bonds with O2 and H2O, reducing oxygen reduction inhibition, while the -Cl group repelled O2, resulting in enhanced inhibition. Free energy analysis of the oxygen reduction reaction supported these findings. These new insights into benzotriazole derivatives’ copper corrosion inhibition mechanisms offer valuable guidance for developing next-generation corrosion inhibitors.

Appraising the corrosion inhibitory efficacy and adsorption mechanism of leaf extract of Datura discolor on low-carbon steel in low pH media via gravimetric experiments and AFM analysis

BackgroundThe study investigated the inhibitory action of Datura discolor leaf extract against the corrosion of low-carbon steel in 0.5 M solutions of three acids. The purpose was to ascertain the effect of extract concentration, immersion time and temperature variation on corrosion inhibitory efficiency, and to relate to existing reports which show that organic molecules in most plant extracts inhibit corrosion. Extraction of the leaves was done by maceration using methanol, and solvent was removed by evaporation to dryness. Classical gravimetric (mass loss) experiments were used, and experimental data were fitted to adsorption isotherm models to ascertain the best approximation. Surface examination of the low-carbon steel substrates was carried out using the atomic force microscope.ResultsInhibitory protective efficiency of extract was found to appreciate with increasing Datura discolor leaf extract concentration at a fixed temperature, with values ranging 77.6–88.8%, 91.35–98.08% and 19.64–44.64% in H2SO4, HCl and HNO3 solutions respectively at 27 °C. Elevation of temperature was found to depreciate the inhibitor efficiency at constant inhibitor concentration. Best isotherm model fitting was obtained with Langmuir model both at 27 °C and 60 °C and in all the hostile media, while Temkin model gave good approximation only at 60 °C and in H2SO4 and HCl solutions only. The negative values of free energy of adsorption (ΔGads0)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\Delta G_{{{\ ext{ads}}}}^{0} )$$\\end{document} suggested that the adsorptive interaction of the inhibitor with the substrate surface was very spontaneous. Values of ΔGads0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta G_{{{\ ext{ads}}}}^{0}$$\\end{document} were all consistent, fluctuating between − 16.35 and − 17.63 kJ mol−1 in both H2SO4 and HCl solutions, and between − 9.76 and − 10.25 kJ mol−1 in HNO3 solution, and this suggests that adsorption of the inhibitor molecules occurred via physisorption. Values of the activation energy of the corrosion reaction (Eact)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(E_{{{\ ext{act}}}} )$$\\end{document} are all < 40 kJ mol−1, suggesting that the inhibition occurred by a physical adsorption mechanism.ConclusionsThe study concludes that Datura discolor crude leaf extract suppressed the corrosion reactions, and the inhibition was found to arise from the physisorptive interaction of the organic molecules with the substrate/solution interface, forming a stabilize inhibitor film on the substrate surface as revealed by the atomic force micrographs.

Corrosion inhibition performance of protein derived carbon quantum dots as corrosion inhibitors on low carbon steel in sulfuric acid solution

Protein derived carbon quantum dots (PCQDs) were successfully fabricated via a hydrothermal method with shrimp meat as the precursor. Subsequently, their corrosion-inhibiting performance on mild steel (L-steel) in a 0.5 mol/L H2SO4 solution was evaluated. Electrochemical impedance spectroscopy (EIS) tests demonstrated that at a concentration of 250 mg/L, the corrosion inhibition efficiency of PCQDs exceeded 90 %. Potentiodynamic polarization (PDP) tests indicated that when the concentration of PCQDs reached 500 mg/L, the corrosion inhibition efficiency was as high as 97.45 %. Comprehensive characterizations of the PCQDs, including X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and ultraviolet–visible spectroscopy (UV–Vis), verified the existence of functional groups such as carboxyl, hydroxyl, and aromatic rings within the PCQDs. These groups are conducive to forming a strong adsorption force on the surface of L-steel and creating a protective layer. Surface morphology analyses carried out by scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed that the surface of L-steel treated with PCQDs was significantly smoother in comparison to untreated samples exposed to acidic conditions. Adsorption studies disclosed a mixed physical and chemical adsorption behavior, and theoretical calculations showed that the N and S atoms in PCQDs preferentially adsorb in a parallel direction. The addition of PCQDs led to a reduction in the diffusion coefficient, indicating that the diffusion of corrosive ions was effectively hindered. The distribution function of PCQDs was 3.48 Å, which suggested that the chemisorption mechanism played a dominant role in the inhibition process.

A Comparison Study on the Recovery of REEs from Red Mud by Sulfation Roasting–Water Leaching and Citric Acid Leaching

In this study, the recovery of rare earth elements (REEs) from red mud (bauxite residue) was explored through a combination of citric acid leaching and sulfation roasting–water leaching processes, introducing an innovative approach to the field. The research uniquely investigates the influence of citric acid on the leaching behavior of REEs and impurities in both untreated red mud and red mud subjected to sulfation roasting, providing a direct comparison of these methodologies. A novel aspect of this study is the evaluation of solvent extraction efficiency using DEHPA, highlighting the selective recovery of REEs over impurities from both citric acid and water-leaching solutions. Furthermore, a comprehensive phase analysis using X-ray diffraction (XRD) was conducted to track the transformations of minerals during the sulfation roasting process, an original contribution to the literature. The findings revealed that over 85% of REEs and major elements such as Fe, Al, Ca, and Ti dissolved in water after sulfation at 105 °C, while iron and titanium dissolution significantly decreased following roasting at 725 °C. Importantly, terbium, neodymium, and gadolinium extraction efficiencies were notably affected by roasting temperature. Citric acid leaching results demonstrated that the direct leaching of red mud leads to higher leaching efficiency than leaching it after the roasting process. Solvent extraction demonstrated lower terbium and neodymium recovery from citric acid solutions compared to water leaching solution. Finally, stripping experiments illustrated that 6M H2SO4 solution is capable of stripping more than 80% of rare earth elements, except terbium.

Nitrogen-doped carbon nanosheet confined PtNi alloy for efficient acidic electrocatalytic hydrogen evolution reaction

Low intrinsic electrocatalytic activity and inferior conductivity limit the application of Ni/NC in acidic electrocatalytic hydrogen evolution reaction (HER). Herein, we prepared nitrogen-doped carbon nanosheet confined PtNi alloy electrocatalysts (PtNi/NC-10) using PtCl62− electrostatic adsorption coupling melamine pyrolysis nitriding strategy. PtNi alloying was confirmed by the crystallinity decrease and lattice expansion of Ni/NC. The alloying and confinement effect of Metal-Organic Frameworks (MOFs) suppresses the oxidation and agglomeration of metal nanoparticles during pyrolysis, thus significantly reducing particle size, increasing specific surface area, and promoting the exposure of active sites. The strong electronic interaction between Pt and Ni optimizeds the surface charge distribution, enhancing the adsorption of H species on electron-rich Pt sites, thereby improving reaction kinetics. In addition, PtNi alloying improves the conductivity of the material, accelerating charge transfer and proton transport. Consequently, the prepared PtNi/NC-10 exhibits superior HER performance than Ni/NC in 0.5 M H2SO4 solution, even comparable to commercial 20 wt% Pt/C, with the overpotentials of 35 mV at 0.01 A cm−2. Furthermore, the electrocatalysts assembled PtNi/NC-10-CP‖RuO2-TFF proton exchange membrane (PEM) electrolyzer only requires 2.32 V cell voltage to achieve 1 A cm−2, presenting practical application prospects. Our work provides a novel idea for designing efficient and stable MOFs confined to alloy-based HER electrocatalysts.

Highly efficient bimetallic counter cations-based tungsten bronzes electrocatalysts developed for sustainable oxygen evolution in acidic solution

This study involves the designing of monophosphate tungsten bronzes (MPTBs) with a combination of earth-abundant Al and Ni counter cations synthesized via the solution combustion as robust, highly efficient electrocatalysts for oxygen evolution reaction (OER) in 1.0 M H2SO4 solution. A series of mixed Al and Ni counter cations-based MPTBs was prepared at different temperatures and characterized with various sophisticated techniques concerning their compositions, morphologies, microstates, and electronic states. The catalyst with Al/Ni ratio of 1:3 of tetragonal cube-shaped MPTB calcined at 700 °C ((Al1/3,Ni)-MPTB7) exhibited an extraordinary OER performance with a larger electrochemically active surface area, almost zero onset overpotential (η), and a lower solar cell-equivalent η (i.e., at 10 mA cm−2) of 199 mV that is lower than that obtained with the state-of-the-art RuO2 catalyst. A progressive enhancement of the performance of the catalysts was noticed for a 12 h OER run, ensuring the robustness of the materials developed for a long-term application. The mixed valency states of tungsten (W), i.e., W5+/W6+ states, along with higher oxygen vacancies of (Al1/3,Ni)-MPTB7 are evaluated to tender suitably oriented active sites for effective adsorption of H2O during the OER. A substantial increase in oxygen vacancies and W5+ state, particularly the W5+4f7/2 state in the catalysts, resulted from a spin-exchange phenomenon during a long-term OER is associated with OER catalytic enhancement. The thus-developed acid-stable, robust MPTBs with mixed Al and Ni counter cations would be an alternative to the pricy noble metal counterparts used in clean energy water splitting technology.

Construction of structurally stable block electrodes with RuO2 distribution for supercapacitor based on TEMPO-treated wood loaded with Ru-TA complex

Block carbon is convenient for energy applications, however constructing composites for electronic energy storage by loading metal oxides on the surface of wood derived carbon is fraught with complications. The mild TEMPO method was employed to treat wood to expand carboxyl groups, followed by introducing tannic acid (TA) to produce Ru-TA complex (underdeveloped provider of RuO2) on wood. These composites were impregnated with H2SO4 and carbonized, transitioning into block electrodes with a clear-stable carbon skeleton and comprising uniformly diffused RuO2. The block electrodes exhibit an impressive specific surface area, with TPWTSC-7 among them completing 812.1406 m2/g. Electrochemical characteristics were investigated using KOH and H2SO4 solutions in three-electrode. Evaluation indicates that RuO2 and electrolyte have a comprehensive effect on performance, with a representative TPWTSC-4 demonstrating the Ct of 189.09 F/g (0.1 A g-1) in KOH solution, while achieving 289.99 F/g (0.1 A g-1) in H2SO4 solution, which is 8.82 times that of TPWSC. The storage mechanism of TPWTSC-0.83, TPWTSC-4 and TPWTSC-7 in H2SO4 solution are affected by diffusion control and capacitance, and TPWTSC-4 emerges a pseudo-capacitive contribution of 63.82 % (5 mV/s). For two-electrode, the easily operable TPWTSC-4//TPWTSC-4 achieves a CT of 34.17 F/g (0.05 A g-1), which also exhibits impressive power density.

Unveiling the effect of strain path-dependent microstructural evolution on the electrochemical behavior of cold-rolled [FeNi]69Cr15Mn10Nb6 high-entropy alloy

In the present work, [FeNi]69Cr15Mn10Nb6 high-entropy alloys (HEAs) were subjected to a heavy cold-rolling process at ambient temperature through two distinct routes, namely unidirectional cold-rolling (UCR) and multistep cross cold-rolling (MSCCR). This was done to investigate the effect of strain path-dependent microstructural evolution on the electrochemical behavior of the alloys in a 0.5 M H2SO4 solution. The as-homogenized specimen displayed a two-phase microstructure with [FeNiNb]-rich dendrites distributed in a nearly homogenous face-centered cubic (FCC) high-entropy alloy matrix. It was found that the [FeNiNb]-rich dendrites elongated, broke down, and elongated along the rolling direction in both processing routes. In the MSCCR-processed specimen, the dendrites exhibited a smaller average size with a more uniform distribution compared to the UCR sample, which was mainly ascribed to the elongation mechanisms in the normal and transverse directions during the MSCCR route. Electrochemical studies demonstrated a decrease in corrosion current density due to high imposed strains in the UCR. Meanwhile, a more positive trend was observed in MSCCR processing. Consequently, achieving uniformly distributed small dendrites and uniform grain refinement through the MSCCR route provided ideal conditions for forming passive layer with superior protection properties.

PEDOT:PSS Films With Very High Thermoelectric Properties Through Water‐Swollen Assisted Reduction With a Tetrakis(dimethylamino)ethylene Solution

AbstractThermoelectric (TE) materials have attracted significant attention because they can be used to directly harvest waste heat into electricity. Organic TE materials like poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) have advantages including high mechanical flexibility, low cost, and low intrinsic thermal conductivity. However, their TE properties are notably inferior to their inorganic counterparts. Here, PEDOT:PSS films with very high thermoelectric properties through the sequential treatments with H2SO4, water, and ethanol solution of tetrakis(dimethylamino)ethylene (TDAE) are reported for the first time. The PEDOT:PSS films can exhibit a Seebeck coefficient of 58.2 µV K−1 and electrical conductivity of 1552 S cm−1, and the corresponding power factor is 526 µW m−1 K−2. The water treatment prior to the TDAE solution treatment is crucial for the high TE properties of PEDOT:PSS films. Without the water treatment, the control PEDOT:PSS films exhibit a Seebeck coefficient of only 32.4 µV K−1 and electrical conductivity of 1124 S cm−1, and the corresponding power factor is only 118 µW m−1 K−2. The effect of the water treatment on the Seebeck coefficient is attributed to the swelling of PEDOT:PSS films, which facilitates the penetration of TDAE from solution into the polymer films and thus the reduction of PEDOT:PSS.

Corrosion behavior of TiZrNbC coatings on TA1 substrates in simulated PEM water electrolysis

A TiZrNbC coating was deposited on the TA1 substrate by magnetron sputtering technology, and the corrosion behaviors of the TiZrNbC coating in a simulated proton exchange membrane water electrolysis (PEMWE) environment under fluctuating potentials were investigated. The microstructures and elemental distributions of the coating were characterized by SEM and EDS. The PEMWE environment was simulated using a dilute H2SO4 solution with pH = 3 and a 5 ppm of fluoride (F-) ions addition, and polarization tests were conducted under the potentials with constant, square and triangular waveforms. The corrosion resistances of the TiZrNbC-coated and bare TA1 substrates were characterized by potentiodynamic polarization, electrochemical impedance spectroscopy and interfacial contact resistance tests. Compared to the bare TA1 substrates, the TiZrNbC-coated TA1 substrates exhibited lower corrosion current densities, higher polarization resistances and lower contact resistances, demonstrating a superior corrosion resistance.

Preparation and Characterization of Waste Fish Bone-Derived Gelatin/Chitosan Plastic Film Incorporated with Green Tea Extract

Fish-derived gelatin has recently been spotlighted as an alternative source following the negative issues of mammalian gelatin, but unfortunately it has poor mechanical properties that limit its application. Herein, an environmental-friendly film was prepared from milkfish (Chanos chanos) bone waste-derived gelatin and modified by adding chitosan, glycerol and sorbitol plasticizers as well as green tea extract to improve its mechanical properties. Gelatin was processed from milkfish bone waste using various concentrations of H2SO4 solution (2%, 3%, and 5%) (v/v) and soaking times of 18 h and 36 h for each of the solutions. The measurement test of pH, ash content, and moisture content were conducted on the gelatin product, and the characteristic functional groups were investigated using Fourier- Transform Infrared Spectroscopy (FTIR). The effect of green tea addition was also evaluated on the thickness, tensile strength, and elongation of the resulting films. The results showed that treatment using H2SO4 concentration of 3% with 36 hours of immersion time produced the best gelatin quality with a pH value of 5.9. Water content and ash content were 14.286% and 3.09%, respectively. The plastic film from this study has mechanical properties similar to polypropylene plastic so that it is expected to be a potential material for food packaging applications.

Development and assessment of eco- and user-friendly geopolymeric stabilizers for sustainable soil improvement

This paper presents an innovative approach to address inherent limitations in traditional geopolymerization methods by focusing on producing eco and user-friendly mechano-chemically activated geopolymeric (M-GP) stabilizers for soil stabilization applications. A comparative analysis is conducted to benchmark the effectiveness of these stabilizers against conventionally activated geopolymer (C-GP) stabilizers. The study also investigates the influence of ground granulated blast furnace slag (GGBFS) amount on the mechanical and durability characteristics of stabilized soil specimens. Furthermore, the effect of activation techniques on the efficacy and strength of soil after sulfuric acid (H2SO4) exposure was investigated. The durability performance was evaluated by submerging the samples in a 1 % H2SO4 solution for a period of 60 and 120 days. The evaluation addresses various aspects such as visual appearance, mass changes, unconfined compressive strength (UCS), ultrasonic pulse velocity (UPV) and the Fourier transform infrared spectroscopy (FTIR) of geopolymer-stabilized soil samples. Results indicate that the UCS of M-GP samples surpassed C-GP-stabilized soil by 12–45 %. Moreover, the geopolymer-stabilized soil exhibited a significant increase in strength, with improvements of 114 %, 247 %, and 361 % observed at GGBFS content levels of 50 %, 75 %, and 100 % by weight, respectively. After exposure to the H2SO4 solution, M-GP-stabilized soil demonstrated superior resistance to sulfuric acid compared to C-GP-stabilized soil. The residual ultimate compressive strength (UCS) for M-GP and C-GP specimens was 80 % and 76 % respectively after being subjected to the H2SO4 solution for 60 days. However, these values further declined to 53 % and 48 % after 120 days of exposure. In addition, the result showed that geopolymer-stabilized soil containing 75 % slag exhibited superior resistance to H2SO4 compared to other stabilized soil samples.

Supercapacitor electrodes derived from ultra-high surface area activated carbon spheres synthesized by fluidized activation

This study thoroughly investigated the effects of activation conditions on pore structure development using response surface methodology with a central composite design. The activated carbon sphere (ACS) derived from phenolic formaldehyde resins by carbonization and fluidized activation was examined and characterized. The pore size distribution of ACS samples was all in the microporous and mesoporous scales. ACS with an ultra-high specific surface area of 3142 m2 g−1 and total pore volume of 1.513 cm3 g−1 was successfully obtained at 900 °C for 4 h. Electric double-layer capacitor (EDLC) electrodes derived from ACS with different activation conditions were examined by using cyclic voltammetry and galvanostatic charge/discharge to comprehend the influence of surface area, pore volumes, and the amount of binder on the electrochemical performance. The optimal EDLC electrode was obtained using ACS with the largest specific surface area and pore volume with 5 wt% of binder addition. The specific capacitance was 143.7 F g−1 in a 1 M H2SO4 solution. The cyclical stability of the carbon electrode was also examined under 5000 cycles, and the charge/discharge efficiency remained nearly 100 % without deterioration. This study provides insights into fabricating ultra-high surface area ACS and their potential application as supercapacitors.

Bimetallic MOF derived Cu3P/Co2P grown on coal-based carbon fibers as self-supporting electrocatalyst for enhanced hydrogen evolution

Transition metal phosphides (TMPs) are often considered as a cost-effective replacement for precious metal catalysts in hydrogen evolution reaction (HER). Herein, the fibers are produced by combining coal with electrospinning technology, and then undergoing a pre-oxidation process for transforming into pre-oxidized coal-based fibers. Subsequently, CuCo-metal organic framework (CuCo-MOF) is grown on the pre-oxidized coal-based fibers using solvothermal method, and the Cu3P/Co2P/coal-based carbon fibers (Cu3P/Co2P/C-CFs) composite catalyst is successfully fabricated by phosphating at low temperature and carbonizing at high temperature. The uniformly grown nanoparticles (NPs) on the surface of C-CFs enhance the electrochemically active area, while the electron transfer between Cu3P and Co2P effectively modulates the electronic structure, increasing the catalytic activity of the catalyst for HER. In addition, the flexible C-CFs not only serve as self-supporting electrode but also effectively inhibit the agglomeration of Cu3P/Co2P NPs. Remarkably, the overpotential of Cu3P/Co2P/C-CFs is 83 mV at 10 mA cm−2 current density for HER in 0.5 mol L−1 H2SO4 solution. This study presents promising strategies for the high value-added utilization of coal and the synthesis of highly effective non-precious metal catalysts.

I Single-Atom Doped P-Rich CoPn Nanocluster@CoP with Enhanced HER.

Constructing I single-atom (ISA) doped CoP electrocatalyst for HER is extremely challenging and has not been reported to date. Herein, an ISA doping-phosphatization strategy is proposed to prepare a novel I single-atom doped P-rich CoPn nanocluster@CoP electrocatalyst (ISA-CoPn/CoP) with enhanced HER performance first. ISA-CoPn/CoP shows a low overpotential of only 44 and 81mV in 0.5m H2SO4 solution, to drive a current density of 10 and 100mAcm-2. ISA and P-rich CoPn nanocluster show unique synergies, which can optimize the H adsorption energy and accelerate the kinetics of HER in the CoP system. The intermediate I─H bond vibration peak is directly observed through in situ Raman testing, demonstrating that ISA doping helps accelerate the HER process. Additionally, the ΔGH of ISA-CoPn/CoP is only 0.05eV by density functional theory (DFT) calculation, which is conducive to H2 evolution.

Enhancing copper corrosion resistance in highly caustic environments: Evaluation of environmentally friendly inorganic inhibitors and mechanistic insights

During this study, two inorganic glasses materials with chemical compositions of (1−x) (2Bi2 O3 ⋅B2 O3)–x BaO (with x=0.2 (BiB-Ba0.2) and x=0.6 and (BiB-Ba0.6)) were synthetized characterized and investigated as viable, ecofriendly, and sustainable inhibitors to mitigate copper corrosion in a highly caustic solution containing 0.5 M H2SO4 solution. To evaluate inhibition processes, several techniques were employed, including potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and atomic force microscopy (AFM). Furthermore, the results show that the two inhibitors studied, BiB-Ba0.2 and BiB-Ba0.6, have higher corrosion inhibition efficiencies at the optimum concentration (10−3 M), reaching 91.2 % and 90.8 %, respectively. Moreover, these findings suggest that the two inorganic compounds elaborated possess inhibitors of mixed types. Copper oxide (Cu2O) production is markedly delayed when the two inhibitors are added to the acid medium, according to the findings of the XRD, FTIR, SEM/EDS, and AFM investigations. This outcome is explained by the development of a shield that lessens surface damage to copper metal, producing a smoother surface morphology.

Designing Mo-based transition metal dichalcogenides for sustainable hydrogen production: Anionic substitution and DFT insight

Anionic substitution is an effective approach to optimize the catalytic activity of Mo based transition metal dichalcogenide (TMD)- MoS2 towards hydrogen evolution reaction (HER). By optimizing the S-to-Se ratio, materials with the ideal Gibbs free energy of hydrogen adsorption (ΔGH) values are synthesized (MoS2, MoS1.4Se0.6, MoS1.2Se0.8, MoSSe, MoSe2) and their HER performance is examined in 0.5 M H2SO4 solution. Density functional theory calculations of hydrogen adsorption energy on the surface of the electrocatalysts show that Se substitution facilitates electron transfer between the catalyst surface and the hydrogen donor, thereby lowering the additional potential required for water splitting, making MoS1.2Se0.8 the most favorable HER electrocatalyst with the lowest value of adsorption energy. Further enhancement in the electrocatalytic activity of mixed anion TMDs has been achieved by the incorporation of carbon nanotubes (CNTs). MoS1.2Se0.8-CNT nanocomposite exhibits superior HER performance with an overpotential of 118 mV and a Tafel slope of 63 mV/decade as compared to MoS1.2Se0.8 sample owing to the synergetic effect from CNTs and MoS1.2Se0.8.

Extract of Silybum marianum (L.) Gaertn Leaves as a Novel Green Corrosion Inhibitor for Carbon Steel in Acidic Solution

In this work, leaves of Silybum marianum (L.) Gaertn were extracted by a one-step extraction method using ethanol as a solvent, and the Silybum marianum (L.) Gaertn extract (SMGE) was firstly employed as a green corrosion inhibitor for carbon steel in 0.5 mol/L H2SO4. The corrosion inhibition performance was studied using weight loss and electrochemical methods, and the anti-corrosion mechanism of SMGE is further analyzed through some surface characterizations and theoretical calculations. The results indicate that SMGE can act as a mixed-type corrosion inhibitor and possess superior corrosion inhibition performance for carbon steel in H2SO4 solution, and the optimum corrosion inhibition efficiency reached 93.06% at 800 ppm SMGE combined with 60 ppm KI. The corrosion inhibition efficiency increased with the rising inhibitor concentration. Surface characterizations illustrated that the inhibitor could physico-chemically adsorb on a metal surface, forming a hydrophobic, protective film.

An experimental and theoretical study of two pyridinium salt derivatives as API 5L Grade B steel corrosion inhibitors in H2SO4 solution

An experimental and theoretical study of two pyridinium salt derivatives as API 5L Grade B steel corrosion inhibitors in H2SO4 solution

Reduced graphene oxide supported meso-pyridyl BODIPY-Cobaloxime complexes for electrocatalytic hydrogen evolution reaction

Creating innovative catalysts utilizing nonprecious metals for the electrocatalytic hydrogen evolution reaction (HER) poses a significant difficulty. We present a cobaloxime (Cox) complex having pyridine (2-Cox) and tetrafluorophenyl-thio-pyridine (4-Cox) functional groups, which contains a 4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) moiety. This combination serves as a catalyst for proton reduction and is immobilized onto reduced graphene oxide (rGO) by π–π stacking between the cobaloxime complex and rGO. Moreover, the unique complex's structures were determined through the application of ultraviolet–visible spectroscopy (UV–Vis), Fourier Transform Infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), and scanning electron microscopy (SEM). The electrocatalytic activity of the two rGO/2-Cox and rGO/4-Cox electrodes towards hydrogen (H2) were examined under both alkaline and acidic conditions. The cobaloxime-modified rGO electrodes demonstrate superior electrocatalytic performance for the HER under acidic conditions compared to alkaline conditions. The overpotential at a current density of 10 mA cm−2 for rGO/2-Cox in 0.5 M H2SO4 is −0.342 V, which is notably lower than the overpotential of rGO/4-Cox (−0.496 V). The Tafel slope for the rGO/2-Cox electrode in a 0.5 M H2SO4 solution is 111 mV.dec−1, but for the rGO/4-Cox electrode it is 156 mVdec−1. This discrepancy suggests that the rGO/2-Cox electrode demonstrates better performance in the HER compared to the rGO/4-Cox electrode.