Surface Analysis Techniques Research Articles

Influence of Sulfate and Iron Reducing Bacteria on Carbon Steel Corrosion in Marine Environments

The current study highlights the corrosion consequences observed in API 5L X65 carbon steel when exposed to a marine-like environment containing carbon dioxide (CO2), in the presence of sulfate- reducing bacteria consortium (C-SRB), iron-reducing bacteria consortium (C-IRB), and a combination of both (C-SRB+C-IRB). The corrosion behaviour was assessed through the utilisation of weight loss and surface analysis techniques. The biofilms and corrosion products were characterised using field emission scanning electron microscopy (FESEM) and infinite focus microscope (IFM), respectively. The results obtained from the weight loss technique provided confirmation that in the absence of bacteria, uniform corrosion was the prevailing mechanism in the medium. The uniform corrosion rate was found to be 0.95 mm/year, which was higher than the pit penetration rate of 0.28 mm/year. The combined actions of the C-SRB+C-IRB consortium result in a synergistic impact, leading to a significantly higher rate of pit penetration compared to the individual activities of SRB. Specifically, the pit penetration rate value of 2.13 mm/year is observed, which is notably higher than the uniform corrosion rate of 0.59 mm/year. The utilisation of surface analysis techniques has shown evidence of the existence of sulfur on carbon steel samples that were subjected to exposure from the C-SRB+C-IRB consortium in a CO2 environment. This sulphur presence is believed to potentially play a role in the development of the iron sulphide (FeS) layer. FeS presence is a contributing factor to the occurrence of pit corrosion due to the SRB metabolite activities. The activities of these metabolites readily dissolve in the medium, hence altering the chemical interface properties of both the metal and the biofilm. For specimens exposed to C-SRB only, the results obtained were almost identical to exposure to the C- SRB+C-IRB consortium. However, the corrosion rate value measured for the C-SRB+C-IRB consortium was higher due to the synergistic effect of the two bacteria. In conclusion, the presence of C-SRB alone and the consortium of C-SRB+C-IRB in a CO2 environment induces the formation of pitting corrosion. The findings of this study are presumed to contribute a deep understanding of the microbiology-influenced corrosion (MIC) mechanism in CO2 environments troubling the oil and gas industry. With a better understanding of MIC, new and improved corrosion prevention strategies can be put into action.

Thorn apple (Datura stramonium) extract acts as a sustainable corrosion inhibitor for zinc alloy in hydrochloric acid solutions

The inhibition effectiveness of diverse concentrations of Datura Fruit Extract (DFE) on the corrosion of zinc in 0.05–0.1 M HCl solutions was examined by weight loss (WL), Electrochemical Impedance Spectroscopy (EIS), potentiodynamic polarization (PDP), and surface analysis techniques. The mass loss method's results demonstrated that raising the DFE concentration improved the efficiency of the inhibition. The maximum inhibition efficiency was 99.40% at 2.0 g/L of DFE. In the temperature ranging from 303 to 333 K, the effect of temperature on the corrosion behavior while adding DFE was also investigated. A DFE extract had been adsorbed on the surface of the metal by Langmuir adsorption isotherm models. It was established that the DFE's activation parameters and negative Gibb's free energy show that rates of adsorption have been spontaneous. According to polarization analysis, DFE regulates both the cathodic and the anodic response. Images obtained using a SEM (Scanning Electron Microscope) reveal that the DFE reduces surface damage. The adsorption inhibition mechanism is supported by the AFM analysis findings. FT-IR (Fourier transform infrared) spectroscopy has been utilized to ascertain the functional group of the DFE. All of the applicable approaches' experimental findings are in good agreement.

Electrodeposition of Zn-Cr Alloys: A Comparison with Pure Zinc

The electrodeposition of zinc coatings is one of the most common surface treatments for providing corrosion resistance to metallic components. From the thermodynamic point of view, zinc is located in a sweet spot, with its reduction potential being lower than most other common metals, while at the same time being not too susceptible to atmospheric corrosion; overall these features make zinc the ideal candidate for the electroplating of sacrificial coatings for corrosion protection. Owing it to its low cost and scalability, zinc electroplating has cemented itself as a cornerstone process in a variety of industrial sectors in the last decades. [1]While zinc coatings corrosion resistance has proved to be satisfactory in most cases, it could still be improved to operate even in more aggressive environments. For this purpose, electrodeposition of zinc alloys with transition metals from the iron group (Ni, Co, Fe) has proven to be a successful method to enhance zinc coatings corrosion resistance. In particular, zinc-nickel alloys have found the greater success among them, due to improved corrosion resistance and mechanical properties. [2]Zinc-chromium alloys also present a good opportunity to improve coatings performance, thanks to the passivating effect of Cr. In fact, electrodeposited ZnCr alloys with a Cr content up to 10.4% were found to exhibit a corrosion potential shifted by up 150 mV in the anodic direction with respect to the pure zinc counterpart. [3] This shift led to a significant decrease in the coating dissolution rate but was sufficiently small that the layers could still preserve their sacrificial nature towards the underlying steel.In this work, ZnCr coatings are deposited on low carbon steel from an acidic sulfate formulation containing Cr(III) ions at various concentrations. The properties of ZnCr coatings are explored by varying the most common parameters such as current density, composition, and pH. Furthermore, the resulting coatings are characterized through conventional surface analysis techniques such as SEM, EDS, XRD and XRF. Finally, the corrosion resistance performance of the ZnCr coatings is compared to pure Zn coatings to highlight the benefits of the alloy.Bibliography[1] R. Winand, “Electrodeposition of Zinc and Zinc Alloys,” Mod. Electroplat. Fifth Ed., pp. 285–307, Feb. 2011.[2] N. Lotfi, M. Aliofkhazraei, H. Rahmani, and G. B. Darband, “Zinc–Nickel Alloy Electrodeposition: Characterization, Properties, Multilayers and Composites,” Prot. Met. Phys. Chem. Surfaces, vol. 54, no. 6, pp. 1102–1140, Nov. 2018.[3] V. Chakarova, T. Boiadjieva-Scherzer, D. Kovacheva, H. Kronberger, and M. Monev, “Corrosion behaviour of electrodeposited Zn-Cr alloy coatings,” Corros. Sci., vol. 140, pp. 73–78, Aug. 2018.

Precise major compounds in Barringtonia acutangula flower – water extract for mitigating carbon steel corrosion

BackgroundPlant extracts have been recognized as prospective and sustainable alternatives with the advantages of high efficiency, eco-friendliness, abundant sources, and ease of regeneration. Even though specific techniques have been applied to identify the major compounds in plant extracts, their values on corrosion inhibitors are still questionable. MethodsThe major compounds in Barringtonia acutangula flower-water extract (BAFE) were first isolated and quantified via various chromatography techniques such as chromatography column and high-performance liquid chromatography (HPLC) method, respectively. The density functional theory (DFT) was used to confirm the electrochemical properties of these compounds and the molecular dynamics (MD) investigated the BAFE film/substrate interactions. Electrochemical techniques were used to study the steel's anticorrosion ability of the extract in 1 M HCl solution. After being immersed to the investigated solution, the sample surface was examined for morphologies, components, and the elemental distribution using various surface analysis techniques (Scanning electron microscopy with energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy). Significant findingsThis study offered a new method to determine the precise major components in BAFE, including ilexsaponin A1 and gallic acid. In addition, DFT and MD simulations indicated that these compounds performed chemisorption on steel surfaces with good adhesion, thermal stability, and enriched electron density. These properties ensure the formation of a smooth protective layer on the steel surface. Potentiodynamic polarization data indicated BAFE as a mixed-type of corrosion inhibitor with a dominating cathodic process. When BAFE concentrations increased from 0 to 3000 ppm, the inhibition performance increased and reached the highest inhibition efficiency of 95.57 % at 3000 ppm. As the concentration further increased to 4000 ppm, the inhibition performance decreased. This can be attributed to the low vivaciousness of organic species in the solution that hinders the absorption process of the protective film on the steel surface.

Study on the effects of pre-erosion initial structures on the CO2 corrosion behavior of X65 carbon steel

The effects of pre-erosion initial structures on X65 carbon steels exposed to CO2 corrosion were studied by various surface analysis techniques and electrochemical measurement methods. The results show that at a CO2 partial pressure of 2.5 MPa, a FeCO3 layer was formed, while at 0.1 MPa, only the Fe3C layer was present. Higher CO2 partial pressure intensified the corrosion process despite the denser FeCO3 layer. Among the different impact angles (5°, 30°, and 90°), 30° had the greatest impact on the samples, followed by 90°. The synergistic effect of CO2 partial pressure and initial structure significantly promoted CO2 corrosion.

Advances in the Use of Atomic Force Microscopy as a Diagnostic Tool for Solar Cells Characterization: From Material Design to Device Applications

Considerable efforts in search for an effective characterization technique for photovoltaic devices with utmost precision is on the increase. For precise analysis and tailoring of device performance, a reliable technique is vital. Atomic force microscopy is one of the leading surface analysis techniques of choice for probing surface patterns in a variety of materials with atomic precision using a cantilever. It has evolved as a reliable technique for the investigation of subatomic scale properties of materials such as photocurrent heterogeneity, electromechanical response, charge distribution, molecular weight effects, and many other material parameters. The integration of artificial intelligence hybrid algorithms in atomic force microscope for optoelectronic device fabrication and characterization has increasingly emerged to be desirable due to its reliability and effectiveness in achieving high image resolution, automated analysis, actuation, and the coupling of manufactured units with a precision down to atomic units. In this review, an investigation of topical developments in the use of atomic force microscopy as a diagnostic tool for solar cells characterization is presented with special focus on polymer solar cells, perovskite solar cells, quantum dots‐sensitized solar cells, dye‐sensitized solar cells, fullerene‐based solar cells, III‐V‐based solar cells, and silicon‐based solar cells.

High-performance protic ionic liquids as additives in lubricating oils with varying polarity

Although ionic liquids (ILs) have proven to be multifunctional and universal lubricant additives, their solubility in different polar lubricating oils varies greatly. This variability restrains their widespread use as general-purpose lubricating additives. To address this issue, three protic ionic liquids (PILs) with high solubility in lubricating oils with differing polarities were selected as additives, and their tribological performances in polyethylene glycol (PEG) and synthetic pentaerythritol carboxylic ester oil (5750) were systematically investigated. These findings were interesting, as PILs effectively improved the lubrication properties of PEG but impaired those of 5750. Additionally, a variety of surface analysis techniques and MD simulation were employed to further explore the lubrication mechanisms of PILs, and results indicated that they exhibited distinct tribological performance.

Understanding the electrochemical interaction between the hybrid bilayer lipid membranes and amyloid‐β

AbstractBackgroundBiomimetic membrane systems can be deposited onto conductive metal surfaces to study the physical properties of membranes as well as the behaviour of proteins within these membranes using electrochemical and surface analytical techniques [1]. Although there are several types of biomimetic membrane, hybrid bilayer lipid membranes (HBLMs) have attracted wide interest. Traditionally, HBLMs have been developed by electrodepositing alkanethiol self‐assembled monolayers onto gold surfaces, which can then be further modified by depositing a secondary phospholipid layer to form the HBLM. Although HBLMs have been widely regarded due to them being robust, relatively straightforward to make, as well as being easy to modify according to the users needs, several concerns surround HBLMs including their reduced fluidity compared to true cell membranes. This is due to the alkanethiol layer being crystalline in nature and more densely packed, resulting in difficulty to reconstitute transmembrane proteins within them.MethodScreen‐printed carbon electrodes are modified with diazonium based phenyl alkyl groups using different protocols to evaluate the biomimetic differences of these novel HBLMs. 2,2‐diphenyl‐1‐picrylhydrazyl is used to prevent the formation of polyaryl layers on the surface of the electrode, hence limiting the electrodeposition to a monolayer. The HBLMs are formed by depositing the second layer in the form of dihexadecyl phosphate, which are analyzed using differential pulse voltammetry, ellipsometry, and X‐ray photoelectron spectroscopy.ResultThe different HBLMs presented are embedded with amyloid‐β1‐42 (Aβ42), the hallmark protein implicated in Alzheimer’s Disease, to assess the protein‐membrane interactions using HBLMs. Aβ42 is known to aggregate to form dimers, oligomers, fibrils, and plaques. Hence using electrochemical techniques, we are able to monitor the aggregation of Aβ42 in the HBLMs. The aggregation process was accelerated by the presence of the bilayer membrane.ConclusionThe electrochemical platform presented here enables us to understand how the interaction of amyloid‐β with the bilayer membrane can alter the aggregation pathways and also affect the formation of toxic oligomer species.

A poly(2,6-diaminopyridine) functionalized magnetic porous carbon nanomaterial for extraction and determination of phenol, nitrophenols, and chlorophenols in water samples

Herein, for the first time, a new method for the simultaneous extraction of phenol (Ph), nitrophenols (NPs), and chlorophenols (CPs) as the priority pollutants was proposed using a magnetic porous carbon coated with poly(2,6-diaminopyridine). The analytes were separated/determined by an HPLC device coupled to a diode array detector. Magnetic porous carbon was obtained by the pyrolysis of MIL-53(Fe) as a precursor and then functionalized with a layer of poly(2,6-diaminopyridine). Next, the synthesized adsorbent was identified by various methods, including FT-IR, XRD, SEM, VSM, surface analysis, and TEM techniques. After that, the design of the experiment strategy was used to identify and optimize the extraction variables. The LODs and linear range were obtained in the range of 0.04–0.15 µg/L and 0.1–500 µg/L, respectively. The one-day RSDs and day-to-day RSDs were gained in the range of 4.2–9.5 % and 5.0–12.5 %, respectively. The enrichment factors and extraction recoveries were obtained in the range of 208–378 and 41.6–75.6 %, respectively. Eventually, the outlined method was employed to analyze diverse water/wastewater samples satisfactorily.

Fabrication of conductive Ag/AgCl/Ag nanorods ink on Laser-induced graphene electrodes on flexible substrates for non-enzymatic glucose detection

An unusual strategy was designed to fabricate conductive patterns for flexible surfaces, which were utilized for non-enzymatic amperometric glucose sensors. The Ag/AgCl/Ag quasi-reference ink formulation utilized two reducing agents, NaBH_{4} and ethylene glycol. The parameters of the ink, such as sintering time and temperature, NaBH_{4} concentration, and layer number of coatings on flexible laser-induced graphene (LIG) electrodes were investigated. The conductive Ag/AgCl/Ag ink was characterized using electrochemical and surface analysis techniques. The electrocatalytic activity of Ag/AgCl/Ag NRs can be attributed to their high surface area, which offer numerous active sites for catalytic reactions. The selectivity and sensitivity of the electrodes for glucose detection were investigated. The XRD analysis showed (200) oriented AgCl on covered Ag NRs, and with the addition of NaBH_{4}, the intensity of the peaks of the Ag NRs increased. The wide linear range of non-enzymatic sensors was attained from 0.003 to 0.18 mM and 0.37 to 5.0 mM, with a low limit of detection of 10 upmuM and 20 upmuM, respectively.The linear range of enzymatic sensor in real sample was determined from 0.040 to 0.097 mM with a detection limit of 50 upmuM. Furthermore, results of the interference studies demonstrated excellent selectivity of the Ag/AgCl/Ag NRs/LIG electrode. The Ag/AgCl/Ag NRs on the flexible LIG electrode exhibited excellent sensitivity,long-time stablity,and reproducibility. The efficient electroactivity were deemed suitable for various electrochemical applications and biosensors.

Materials characterization: Can artificial intelligence be used to address reproducibility challenges?

Material characterization techniques are widely used to characterize the physical and chemical properties of materials at the nanoscale and, thus, play central roles in material scientific discoveries. However, the large and complex datasets generated by these techniques often require significant human effort to interpret and extract meaningful physicochemical insights. Artificial intelligence (AI) techniques such as machine learning (ML) have the potential to improve the efficiency and accuracy of surface analysis by automating data analysis and interpretation. In this perspective paper, we review the current role of AI in surface analysis and discuss its future potential to accelerate discoveries in surface science, materials science, and interface science. We highlight several applications where AI has already been used to analyze surface analysis data, including the identification of crystal structures from XRD data, analysis of XPS spectra for surface composition, and the interpretation of TEM and SEM images for particle morphology and size. We also discuss the challenges and opportunities associated with the integration of AI into surface analysis workflows. These include the need for large and diverse datasets for training ML models, the importance of feature selection and representation, and the potential for ML to enable new insights and discoveries by identifying patterns and relationships in complex datasets. Most importantly, AI analyzed data must not just find the best mathematical description of the data, but it must find the most physical and chemically meaningful results. In addition, the need for reproducibility in scientific research has become increasingly important in recent years. The advancement of AI, including both conventional and the increasing popular deep learning, is showing promise in addressing those challenges by enabling the execution and verification of scientific progress. By training models on large experimental datasets and providing automated analysis and data interpretation, AI can help to ensure that scientific results are reproducible and reliable. Although integration of knowledge and AI models must be considered for the transparency and interpretability of models, the incorporation of AI into the data collection and processing workflow will significantly enhance the efficiency and accuracy of various surface analysis techniques and deepen our understanding at an accelerated pace.

Ketoprofen-loaded PLGA-based bioactive coating prepared by supercritical foaming on a TiAl6V4 substrate for local drug delivery in orthopedic applications

In this study, a novel biodegradable poly(lactic-co-glycolic) acid coating containing a model anti-inflammatory drug (ketoprofen) was prepared on TiAl6V4 substrate for use in orthopedic medicine by a two-step process combining drop casting and supercritical CO2-assisted foaming. The prepared coating was first investigated by surface analysis techniques using time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy. The combined results confirmed the loading of ketoprofen and its homogeneous spatial distribution in the coating. 3D profilometry revealed increased surface roughness of the coating compared to the bare TiAl6V4 substrate, which is favorable for cell adhesion. Furthermore, the electrochemical measurements (i.e., electrochemical impedance spectroscopy and potentiodynamic curve measurements) demonstrated that the coating application significantly mitigated corrosion compared to the bare TiAl6V4 substrate. In vitro drug release tests revealed extended drug release in simulated body fluids with zero-order release kinetics. Finally, the promising cell testing results using adipose-derived mesenchymal stem cells and osteoblasts confirmed the applicability of the coating for implants. Overall, the results of this study highlight the significant potential of the developed bioactive coating for future orthopedic applications.

Determination of key factors affecting biofilm formation on the aged Poly(ethylene terephthalate) during anaerobic digestion

Biofilm formation on plastic surface is a growing concern because it can alter the plastic surface properties and exacerbate the ecological risk. Identifying key factors that affecting biofilm formation is critical for effective pollution control. In this study, the poly (ethylene terephthalate) (PET) was aged in water and air conditions with UV irradiation, then incubated in the digestate of food waste anaerobic digestion to allow biofilm formation. Surface analysis techniques, including scanning electron microscopy (SEM), atomic force microscopy (AFM), and Fourier-transform infrared spectroscopy with attenuated total reflection (FTIR-ATR), were utilized to investigated the changes in the topography, roughness, hydrophily, and functional groups change of the PET surface during the aging process. Confocal laser scanning microscopy (CLSM) was used to determine the distribution of microorganisms on the PET surface after incubation in the digestate. This study focused on understanding the interactions between the PET surface and biofilm to identify critical surface factors that affect biofilm formation. Results showed that the four months aging process decreased the contact angle of the PET surface from 96.92° to 76.08° and 68.97° in water and air conditions, respectively, corresponding to an increase of 44% and 70% in the surface energy. Additionally, aging in air conditions led to a rougher surface compared to water conditions. The arithmetic roughness average (Ra) of the PET-Water was 11.0 nm, comparable to that of the pristine PET, while the value of PET-Air was much higher (43.9 nm). The results further indicated that biofilm formation during anaerobic digestion was more sensitive to roughness than hydrophily. The PET surface aged in air conditions provided a more suitable environment for microbial reproduction, leading to the aggradation of living cells.

Inhibition of the initial stages of corrosion by 2-mercaptobenzothiazole adsorption and the effects of interfacial oxides on copper in neutral chloride conditions

Advanced surface analytical techniques were used to study 2-mercaptobenzothiazole (2-MBT) adsorption and interfacial oxide effects on copper, and cyclic voltammetry was used to characterize corrosion inhibition in NaCl solution. 2-MBT adsorbs on metallic copper by its sulphur atoms along with a small fraction of nitrogen atoms. The 2-MBT film formed is thicker when the interfacial oxide is less. Upon anodic polarisation, a direct correlation between the thickness of 2-MBT layer and protection against corrosion initiation is observed. The metal-organic complexes, formed by an interaction between 2-MBT and Cu(I) ions, do not offer additional protection to the substrate.

Biosynthesis of novel Hypercium sabrum extract mediated functionalized Ag@Fe3O4@SiO2 NCs for the efficient removal of poisonous pollutants: Greener journey and bioactivity

The full phytochemical profile and elemental analysis of the Hypercium sabrum plant extract as natural reducing media was investigated. The plant then was employed for green fabrication of recyclable 1-(3-(Trimethoxysilyl)propoxy)-1-hydroxy-2-methylallyl format (TMSPHMAF) and 5-Chloro-1-phenyl tetrazole (CPT) functionalized Ag@Fe3O4@SiO2 nanocomposites (NCs) and their formation mechanism. The structure of green fabricated NCs was elucidated using spectrophotometric, spectroscopic and surface analysis techniques. Also, for better catalytic performance of NCs in reduction of toxic nitro compounds and organic dyes and evaluation of potential removal efficiency (RE) of catalysts, the zero-point charge pH (pHZPC) of their surface was studied. Furthermore, the antimicrobial activities and scolicidal effect of NCs were studied against current pathogenic bacteria and hydatid cysts protoscolices.

Elucidating the corrosion characteristics of brine heater and evaporator condenser alloys during acid cleaning of MSF plants and its mitigation

Inorganic scaling is a serious operational challenge in MSF technology which is managed through acid cleaning. The corrosion of MSF tubing materials during acid cleaning is a serious threat to the integrity of MSF evaporators, therefore the use of suitable corrosion inhibitors is a necessity. In the present work, a new corrosion inhibitor, poly(N1,N1-diallyl-N6,N6,N6-tripropylhexane-1,6-diaminium chloride) (PDTDC) is proposed and assessed in terms of performance in typical acid-cleaning conditions. The corrosion of CuNi30 and CuNi10 alloys and their protection mechanisms have been studied using weight loss, electrochemical, and surface analysis techniques. The results reveal that alloys corroded actively but also showed some degree of passivation. The CuNi30 exhibits higher corrosion resistance than CuNi10. PDTDC reasonably inhibited the alloys' corrosion and remained stable for 72 h. The addition of 100 mg/L PDTDC to the corrodent reduces the corrosion rate of CuNi30 and CuNi10 from 1.60 ± 0.08 mm/y and 18.96 ± 0.95 mm/y to 0.37 ± 0.02 mm/y and 8.85 ± 0.44 mm/y resulting in surface protection of 77 % and 53 %, respectively after 72 h at 30 °C under static conditions. Inhibition efficiency of 73 % and 79 % is afforded by PDTDC (100 mg/L) for CuNi10 and CuNi30, respectively after 72 h immersion at 40 °C under hydrodynamic conditions. PDTDC is a highly promising starting material for inhibitor formulation for acid-cleaning applications.

Novel Porous Organic Polymer Catalyst with Phosphate and Sulfonic Acid Sites for Facile Esterification of Levulinic Acid.

Biomass-derived value-added materials such as levulinic acid (LA) are favorable natural resources for producing ester-based biolubricants owing to their biodegradability, nontoxicity, and excellent metal-adhering properties. However, highly active catalysts must be developed to carry out efficient esterification of LA with aliphatic alcohols, especially long-chain aliphatic alcohols. In this study, we developed a novel porous covalent organic polymer catalyst (BPOP-SO3H) with dual acid sites, phosphate and sulfonic acid sites, for the esterification of LA. The prepared BPOP-SO3H catalyst was verified using various surface analysis techniques. BPOP-SO3H exhibited 98% LA conversion with n-butanol and 99% selectivity for butyl levulinate ester within 30 min, which is superior to that of most reported catalysts. BPOP-SO3H also showed high LA conversion and ester selectivity when other aliphatic alcohols were used. Moreover, BPOP-SO3H showed good recyclability for five consecutive cycles. We believe that incorporating a high density of acid sites into a porous polymer with a large surface area and hierarchical pores is a promising approach for developing heterogeneous acid catalysts for the production of alkyl levulinate esters from LA.

Corrosion behavior of 7B04 aluminum alloy under the synergistic effect of Lacticaseibacillus paracasei and Acinetobacter lwoffi

Microbially influenced corrosion (MIC) is a multifaceted phenomenon that is influenced by the synergistic activity of various bacterial species that thrive within biofilms. The present study aims to investigate the impact of interspecies relationships on the corrosion behavior of aluminum alloy (Al alloy). To achieve this, cultures of Lacticaseibacillus paracasei (L. paracasei) and Acinetobacter lwoffi (A. lwoffi) were mixed and analyzed. The electrochemical experimental findings indicated that the 7B04 Al alloy exhibited the lowest Rct value and the highest corrosion current density when immersed in the mixed system. The utilization of surface analysis techniques, such as scanning electron microscopy and stereomicroscope, had led to the discovery of a significant number of corrosion pits in the mixed system. This finding suggested that the corrosion phenomenon was more severe than previously anticipated. The growth curve analysis revealed a synergistic interaction among the mixed bacterial species. The co-cultivation of A. lwoffi and L. paracasei resulted in increased growth activity of L. paracasei in comparison to its growth in a single system. The occurrence of dominant colonies and the development of biofilms were identified as the primary factors contributing to localized corrosion. Furthermore, the combined action of the two bacterial strains exhibited a synergistic effect that exacerbated the corrosion process.

Advancing sustainable solutions: Harnessing polyaniline/BiOCl/GO ternary nanocomposites for solar-powered degradation of organic pollutant and photocatalytic hydrogen generation

Recently, polyaniline-based photocatalysts have gained great attention due to their narrow band gap (E = 1.77 eV), which enables them to absorb a significant amount of visible light (∼43%) in the solar spectrum. In this study, we have synthesized a ternary nanocomposite (PANI/BiOCl/GO) through an oxidative polymerization approach, incorporating polyaniline (PANI), graphene oxide (GO), and bismuth oxychloride (BiOCl). Different weight percentages of composites (GO/BiOCl: 0.5%, 1%, 2.5%, and PANI: 99.5%, 99%, 97.5%) were prepared and named as 0.5PBG, 1PBG, and 2.5PBG, respectively. The ternary nanocomposite's successful development, crystallinity, purity, porosity, and optical properties were evaluated through several spectroscopic and surface analysis techniques, including UV–Vis-DRS, PL, XRD, XPS, BET, and EDS analysis. FESEM and HRTEM images unveiled the porous characteristics of PANI, the morphology of exfoliated GO layers, and the nanoplate-like structure of BiOCl. The ternary nanocomposite was finally tested for its ability to degrade an organic dye, rhodamine-b (Rhb), and in the process also generate solar-light-driven green hydrogen by water half-splitting. The composite achieved about 90% detoxification (assigned from GC-TCD by analyzing the evolved CO2 gas after degradation) and 96% color removal of Rhb dye within 120 min. The degradation of Rhb by 1PBG displayed a first-order reaction, featuring a rate constant 7.25 times higher than that observed for pure PANI, 3.8 times higher than for pure GO, and 3.9 times higher than for pure BiOCl. Thus, the ternary composites achieve a good amount of synergy. Significantly, this reaction rate constant is 4.7 times greater than the rate observed with commercially used TiO2–P25 photocatalyst. Various reaction parameters including solution pH, different illumination areas, catalyst dosage, and the study of scavengers were investigated to understand their effects on the degradation reaction. The photocatalyst's reusability effectiveness was evaluated over 6 cycles, and its stability was subsequently confirmed through XRD and ICP-OES analysis. The LC-MS study revealed the identification of various intermediates and end products following the degradation reaction. The nanocomposite also produced 1000 ppm of hydrogen gas with an apparent quantum efficiency (AQE) of 17.97% when CH3OH was used as a sacrificial agent, 500 ppm (AQE of 9.69%) in the acidic conditions, and 600 ppm (AQE of 11.63%) in the basic conditions. In a broader perspective, this endeavor paves the way for exploring fresh opportunities in the utilization of this ternary nanocomposite. Its potential extends beyond accelerating dye degradation to encompass diverse solar-driven applications as well.

Intermediate Confinement for Selective Ammonia Electrosynthesis from Nitrate on Robust Mesoporous Metal Catalysts

AbstractMesoporous metals have received massive research interests in catalysis and electrocatalysis due to their unique structural features. However, most studies have focused on enhancing activity with much less focus on promoting selectivity. Here, it is reported that the design of bimetallic palladium‐copper (PdCu) alloys at mesoscopic level is a reliable and robust strategy to confine the reaction intermediate and thus boost nitrate reduction reaction (NITRR) electrocatalysis for selective NH3 electrosynthesis. The optimized PdCu mesoporous nanospheres (MSs) disclose a high electrocatalytic NO3−‐to‐NH3 performance with NH3 Faradaic efficiency () of 85%, yield rate of 3058 µg h−1 mg−1, energy efficiency of 31%, and multi‐turn stability. The combination of surface analysis and experimental techniques reveals that the high NO3−‐to‐NH3 performance results from highly penetrated and active mesoporous channels of PdCu MSs that not only kinetically facilitate the adsorption and reactivity of NO3− but also enhance the confinement of key intermediate (NO2−) toward an eight‐electron NITRR pathway for selective NH3 electrosynthesis. More importantly, in accompany with compositional control, trimetallic PdCuRu alloy MSs disclose a superior of 95% and an impressive NH3 yield rate of 8518 µg h−1 mg−1 for selective NO3−‐to‐NH3 electroreduction.