Reduction Of Oxide Research Articles

Selective Electrocatalysis of Nitrous Oxide Reduction Reaction to Nitrogen at Carbon-Supported Pt–Pd–Sn Nanoparticles

Nitrous oxide (N2O) is the third largest greenhouse gas and must be removed using a green method at ambient conditions such as electrocatalysis. Here, we report carbon-supported Pt–Pd–Sn nanoparticles (Pt–Pd–Sn/C)...

From defects to catalysis: mechanism and optimization of NO electroreduction synthesis of NH3.

Ammonia (NH₃) is a crucial industrial raw material, but the traditional Haber-Bosch process is energy-intensive and highly polluting. Electrochemical methods for synthesizing ammonia using nitric oxide (NO) as a precursor offer the advantages of operating under ambient conditions and achieving both NO reduction and resource utilization. Defect engineering enhances electrocatalytic performance by modulating electronic structures and coordination environments. In this brief review, the catalytic reaction mechanism of electrocatalytic NO reduction to NH3 is elucidated, with a focus on synthesis strategies involving vacancy defects and doping defects. From this perspective, the latest advances in various catalytic reduction systems for nitric oxide reduction reaction (NORR) are summarized and synthesized. Finally, the research prospects for NO reduction to NH₃ are discussed.

Platinum Nanoparticles Supported by Carbon Nanotubes: Improvement in electrochemical sensor performance for caffeine determination.

Platinum nanoparticles supported by carbon nanotubes were obtained by a simple chemical route and used for preparation of electrochemical sensor towards caffeine determination. Carbon nanotubes were used before and after an acid treatment, yielding two different materials. Morphological and structural characterization of these materials showed platinum nanoparticles (size around 12 nm) distributed randomly along carbon nanotubes. Modified electrodes were directly prepared through a dispersion of these materials. Voltammetric studies in the presence of caffeine revealed an electrocatalytic effect of platinum oxides, electrochemically produced from the chemical oxidation of the platinum nanoparticles. This behavior was explored in the development a selective method for caffeine determination based on platinum oxide reduction at a lower potential value (+0.45 V vs. Ag/AgCl). Using the best set of experimental conditions, it was shown a linear relationship for the caffeine concentration ranging from 5.0 to 25 µmol L-1 with a sensitivity of 449 nA L µmol-1. Limits of detection and quantification of 0.54 and 1.80 µmol L-1 were calculated, respectively. Recovery values for real samples of caffeine pharmaceutical formulations between 98.6% and 101.0% (n = 3) were obtained using the proposed procedure. Statistical calculations showed good concordance (95% confidence level) between the added and recovery values.

Characterization of iron nugget produced from iron ore concentrate in a microwave oven using a biomass-based reductant

This study is concerned with the characterization of iron nuggets obtained from the reduction of an iron oxide concentrate in a microwave oven using a biomass-based reducing agent. In the experiments, the concentrate of iron ore consisting of hematite and magnetite minerals supplied from Elazig region and containing 67.29% Fe after enrichment, and as a reducing agent, tea plant wastes containing 94.68% C and 0.03% S after carbonization was used. Carbon required for the reduction of iron oxides to iron was stoichiometrically added to the concentrate with a grain size of -45 µm after its basicity ratio was adjusted. The composite pellets produced after the addition of reducing agent and flux (CaO) were subjected to reduction in a household microwave oven at different times. After the process, optimum (Fe3O4+Fe2O3)/C=1/4, basicity ratio (CaO+MgO)/(SiO2+Al2O3) =1.2 results were obtained. It was seen that the metallic part contained 96.6% Fe, 2.4% C after being separated from the slag and that the metallic phase was separated from the slag very easily. As a result of the microstructure investigations, it was found that the product obtained had similar properties to white cast iron properties.

Oxidative Desulfurization of Simulated Diesel Fuel by Synthesized Tin Oxide Nano-Catalysts Support on Reduced Graphene Oxide

The modified Hummers method was applied to prepare graphene oxide (GO) from the graphite powder. Tin oxide nanoparticles with different loading (10-20 wt.%) supported on reduced graphene oxide were synthesized to evaluate the oxidative desulfurization efficiency. The catalyst was synthesized by the incipient wetness impregnation (IWI) technique. Different analysis methods like FT-IR, XRD, FESEM, AFM, and Brunauer-Emmett-Teller (BET) were utilized to characterize graphene oxide and catalysts. The XRD analysis showed that the average crystal size of graphene oxide was 6.05 nm. In addition, the FESEM results showed high metal oxide dispersions on the rGO. The EDX analysis shows the weight ratio of Sn is close to its theoretical weight. The reduction of metal oxide and (GO) has occurred in one step at temperatures of 400 °C for 2 hours. The performance of the catalysts for dibenzothiophene (DBT) removal using H2O2 as an oxidizing agent was determined under a range of different operating conditions. The results showed that the maximum desulfurization was 71.68% in the best conditions (DBT concentration = 385 ppm, time = 90 min, temperature = 60 oC, catalyst dosage = 0.04g, and amount of oxidant = 0.375 ml).

Reactivity Controlled Compression Ignition Engine Powered with Plastic Oil and B20 Karanja Oil Methyl Ester

In the early stages of the investigation, plastic oil was mixed with conventional fuel in various proportions, revealing that a 30% volume fraction of plastic oil was optimal when combined with diesel. Building on this, the current study incorporated biodiesel in a 30% volume fraction into the test sample (30PO+70D) at different blending ratios of 10%, 20%, 30%, and 40%. The experimental effects implied B20 blend, representing 20% biodiesel in the test sample, led to reduced emissions compared to the baseline test sample blend. Although there was a slight decrease in performance and fuel consumption, particularly at larger loads, the addition of biodiesel showed a trend of reducing emissions. The power of the diesel locomotive tended to increase with higher biodiesel concentrations, despite biodiesel blends exhibiting delayed combustion. Notably, biodiesel blends demonstrated a reduction in smoke, nitrogen oxides (NOx), and carbon monoxide (CO) levels at maximum brake power. Considering these results, the B20 blend, consisting of plastic oil and diesel, presents itself as a shows potential applicant for future studies because of favorable performance, combustion characteristics, and cleaner emissions.

Hybrid Pore Formation in Copper Spheres by Gas Entrapment and Oxide Reduction

Solid‐state methods for producing porous metals vary greatly in their approaches and outcomes, and they often result in distinctly different pore sizes and/or characteristics. By combining methods in a hybrid process, it is possible that unique porous structures can be made that are simpler to produce, have improved functional properties, or are otherwise superior to any single approach. For the first time, a combination of gas entrapment and oxide reduction to produce microscale porosity in millimeter‐scale copper spheres created by planetary milling is reported. The milling process entraps Ar in micron to submicron pores within the spheres, which are comprised of a Cu 2 mol% CuO metal matrix composite. Upon heating at 800 °C in an inert atmosphere, the individual spheres expand and form ≈29% closed porosity with an average pore size of 1.5 μm. When those spheres are then reheated to 600 °C in a reducing atmosphere, the porosity is converted to being almost entirely open with an average size of 2.3 μm. In addition to the unique nature of the porosity, the processing of the spheres is unusual in that it is completed after only 90 min of milling.

Novel microbial synthesis of rGO nanosheets for effective photocatalytic remediation of Acid Blue 113 dye, improved seed germination, antimicrobial and antioxidant applications

We report for the first time reduction of graphene oxide (GO) nanosheets (NS) by an isolated bacterium from Lonar lake Bacillus cabrialesii RIRD-SK (MCC 4670). Facile, rapid, ecofriendly, and cost-effective biological approach makes it advantageous over physical and chemical methods. Isolated bacterial strain is deposited in Gene Bank accession number MMZ151886. The physiochemical characterization of rGO NS revealed formation of dark black precipitate within 8 h. UV–Visible spectra of rGO shows absorption peak mainly at 269 nm. Fourier-transform infrared spectroscopy (FTIR) revealed presence of functional biomolecules involved in capping and stabilization of NS. X- ray diffraction (XRD) pattern of rGO confirms pure crystal structure. Scanning electron microscopy (SEM) of rGO showed ultrathin graphene NS morphology having thickness less than 3.5 nm. The elemental composition of graphene oxide (GO) and rGO was studied by energy dispersive spectroscopy (EDS) confirms bacterial reduction GO. Specific surface area rGO about 139.53 m2/g was measured by Brunauer-Emmett-Teller (BET) technique. Raman spectroscopy indicates decrease oxygen containing functional group after bacterial reduction with unique fingerprint of material. The rGO NS showed 90.10 % degradation of Acid Blue 113 diazo dye within 45 min. Bioremediation was confirmed with the help of UV–Visible spectroscopy, thin layer chromatography (TLC), FTIR, High-performance liquid chromatography (HPLC) and Liquid chromatography mass spectroscopy (LCMS). Reduced toxicity of the degraded products was observed by the phytotoxicity experiment. A mechanistic degradation pathway has been proposed. rGO NS also exhibit good antimicrobial and antioxidant properties emphasizing its role in biomedical field.

Numerical Study on Compact Design in Marine Urea-SCR Systems for Small Ship Applications

With increasingly stringent emissions legislation, such as that stipulated by the International Maritime Organization, for nitrogen oxide emission reduction in marine diesel engines, the imperative of curtailing nitrogen oxide emissions from marine diesel engines is intensifying. Consequently, the significance of aftertreatment technologies, including diesel particulate filters (DPFs) and selective catalytic reduction (SCR), is poised to grow substantially. In particular, a redesign is required to reduce the size of DPF and SCR systems for application in small ships. In this study, we varied the shape of the filters in DPF and SCR systems, aiming to achieve a distinct flow pattern and enable overall miniaturization. The performance metrics, including the nitric oxide (NO) reduction rate, NH3 slip rate, and pressure drop, of the redesigned models were compared with those of the conventional model. Computational fluid dynamics simulations were used to compare the performance of the redesigned model with that of the conventional model in terms of NO reduction and pressure drop. The redesigned system achieved a NO reduction rate of 6.9% below that of the conventional system, offering additional noteworthy benefits such as a 50% reduction in both pressure and overall length.

Electron transition enhanced in-situ co-reduction mechanism enabling high-capacity and stable lithium storage for MoO3-x anode

Transition metal oxides (TMOs) often achieve excellent performance through micro-scale regulation and structural evolution, especially as electrode materials for lithium-ion batteries (LIBs). Recently, in order to improve the inferior rate capability, sluggish reaction kinetics, and fast capacity decay of transition metal oxide MoO3 during a long-term charge/discharge process, a variety of composite materials and synthetic routes have been developed. However, the expensive multi-step synthesis, weak interaction between composites, and poor intrinsic conductivity of MoO3 severely hinder the large-scale commercial application of composites. Therefore, a simple, green and low-cost electron transition enhanced one-step co-reduction strategy is proposed to synthesize a novel MoO3-x nanoparticle/few-layer reduced graphene oxide (rGO) composite (denoted as MNR) with strong terminal-bonding (MoO2–O–C-rGO). The strategy ingeniously realizes the fabrication of oxygen vacancies (MoO3-x) and the in-situ reduction of graphene oxide (GO), as well as accomplish the dual regulation of scale and structure by forming a strong terminal-bonding effect. Significantly, the obtained MNR anode exhibits an ultrahigh discharge capacity (1415 mA h g−1 at 1.0 A g−1) and long cycle stability (94 % capacity retention after 700 cycles), which is superior to the previously reported MoO3-based composites. Moreover, the full battery coupled with LiFePO4 cathode also reveals a competitive energy density (369 Wh kg−1). The results suggest a novel approach for the fabrication and wide application of TMOs/rGO composites.

Selective catalytic reduction of NOX with CH4 over In/SSZ-13 zeolites: The enhancement of high-temperature catalytic activity by Ce modification

The selective catalytic reduction of nitrogen oxides by methane (CH4/NOX-SCR) is a potential technique for the abatement of the NOX emissions from lean-burn GDI engines, due to the excellent thermal stability of CH4. This work focuses on the promotion of In/SSZ-13 catalysts by Ce modification for the CH4/NOX-SCR performance at high temperatures. A series of In/SSZ-13 and Ce-In/SSZ-13 catalysts were prepared using the wetness impregnation method. The effects of Ce modification on the catalytic performance were analysed in detail using the scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflectance spectrum and temperature-programmed desorption/reduction techniques. The results show that the Ce modification significantly enhances the high-temperature activity of the In/SSZ-13 catalysts for the NOX-SCR reaction, especially for the 5 wt% Ce-15 wt% In/SSZ-13 sample which has more than 75% NOX conversion at 390–700 °C. In addition, the Ce modification enhances the water vapor tolerance of the catalyst sample. The Ce modification increases not only the concentration of surface chemisorption oxygen species, but also the relative amount of InO+ species which serve as the main active sites for CH4 activation. Furthermore, the incorporation of Ce into In/SSZ-13 greatly promotes NOX adsorption on the catalyst surface. Most importantly, the Ce modification makes In species well-dispersed on the catalyst surface and thus suppresses the formation of bulk In2O3 species which are more active for the CH4 non-selective oxidation. The combination of all these effects results in the Ce-In/SSZ-13 samples with the superior catalytic activity.

Unveiling Pseudo‐Inert Basal Plane for Electrocatalysis in 2D Semiconductors: Critical Role of Reversal‐Activation Mechanism

AbstractPartially occupied orbitals play a pivotal role in enhancing the performance of electrocatalyst by facilitating electron acceptance and donation, thus enabling the activation of molecular bonds. According to this principle, the basal plane of most 2D semiconductors is inert for electrocatalysis because of the fully occupied orbitals at the surface. Here, taking monolayer CrX (X = P, As, Sb) and Cr2PY (Y = As, Sb) as examples and through first‐principles calculations, it is revealed that even with fully occupied surface orbitals, the basal planes exhibit remarkable catalytic activity for the nitrogen oxide reduction reaction (NORR). This leads to the concept of the pseudo‐inert electrocatalyst. The underlying physics behind such pseudo‐inert character can be attributed to the reversal‐activation mechanism: contrary to conventional expectations, the adsorbed NO molecule reversely triggers the activity of the inert basal plane first, and then the basal plane activates NO molecules, forming the intriguing “Reversal Activation‐Transfer‐Donation‐Backdonation” process. This study further predicts that such pseudo‐inert character can demonstrate many distinctive properties, for example, it can introduce a novel type of surface catalysis, one that selectively targets radicals possessing an inherent dipole moment such as NO. The explored phenomena and insights greatly enrich the realms of electrocatalysis and 2D materials.

The maize ATP-binding cassette (ABC) transporter ZmMRPA6 confers cold and salt stress tolerance in plants.

ZmMRPA6 was cloned and characterized as the first ATP-binding cassette (ABC) transporter in maize to be proven to participate in cold and salt tolerance. Homologous genes AtABCC4 and AtABCC14 of ZmMRPA6 also responded to salt stress. ATP-binding cassette (ABC) proteins are major transmembrane transporters that play significant roles in plant development against various abiotic stresses. However, available information regarding stress-related ABC genes in maize is minimal. In this study, a maize ABC transporter gene, ZmMRPA6, was identified through genome-wide association analysis (GWAS) for cold tolerance in maize seeds germination and functionally characterized. During germination and seedling stages, the zmmrpa6 mutant exhibited enhanced resistance to cold or salt stress. Mutated of ZmMRPA6 did not affect the expression of downstream response genes related cold or salt response at the transcriptional level. Mass spectrometry analysis revealed that most of the differential proteins between zmmrpa6 and wild-type plants were involved in response to stress process including oxidative reduction, hydrolase activity, small molecule metabolism, and photosynthesis process. Meanwhile, the plants which lack the ZmMRPA6 homologous genes AtABCC4 or AtABCC14 were sensitive to salt stress in Arabidopsis. These results indicated that ZmMRPA6 and its homologous genes play a conserved role in cold and salt stress, and functional differentiation occurs in monocotyledonous and dicotyledonous plants. In summary, these findings dramatically improved our understanding of the function of ABC transporters resistance to abiotic stresses in plants.

Temperature Dependent Operando High Energy Surface X-Ray Diffraction Studies of Pt(111) Oxidation

Platinum electrocatalysts are still widely used as cathode material in proton-exchange membrane fuel cells (PEMFC) because of their high ORR activity. However, their long-term stability is limited due to degradation processes. This degradation is partly caused by Pt oxidation and oxide reduction, which lead to irreversible surface restructuring and subsequently Pt dissolution. To increase the lifetime of PEMFCs it is mandatory to understand the mechanisms behind the degradation on an atomistic level. This requires studies by structure sensitive in situ methods, in particular, also studies at the elevated temperatures typically employed in PEMFCs operation.Previous studies revealed that in the initial stage of oxide formation Pt atoms are extracted out of the surface and form an ultra-thin oxide layer directly above the surface. This extraction is long known as place exchange [1], but the atomic-scale details of the surface oxide structure, the extraction mechanism, and especially the kinetics of the initial oxide growth were only recently clarified [2-7]. It was found that the structural arrangement of the Pt atoms within the surface oxide on the Pt(111) and the Pt(100) surface is distinctly different, leading to differences in the oxidation/reduction kinetics, the reversibility of the surface oxidation/reduction process, and the amount of Pt dissolution into the electrolyte.Recently, we performed fast operando high-energy surface X-ray diffraction (HESXRD) studies, in which we investigated the initial extraction of Pt atoms on Pt(111) during potential cycles. Surprisingly, it was found that the Pt extraction during the anodic sweep is largely independent of the potential sweep rate, although the peak cyclic voltammograms (CVs) associated with the charge transfer during surface oxidation showed a pronounced shift [7-9]. This suggests that the Pt extraction is a fast process, rather driven by potential and not directly coupled to the slow formation of surface oxygen species. However, the Pt extraction during the anodic sweep and the re-insertion during the cathodic sweep still exhibit significant hysteresis, indicating a complex multistep oxidation kinetics.Previous electrochemical studies of Pt(111) electrodes revealed that the described influence of oxidation/reduction kinetics and the reversibility of the charge transfer processes increase at elevated temperature [10]. However, the temperature dependence of the Pt extraction behavior is currently unknown, because all previous structural studies of oxide growth and reduction have been performed exclusively at room temperature.For the experiments at elevated temperatures we developed a new setup for HESXRD studies of single crystals, which combines a hanging meniscus electrochemical cell for operando X-ray diffraction measurements with an inductive heating device in a joint Ar-filled compartment. This setup allows direct (re-)preparation of the aligned Pt single crystals on the diffractometer. By this, the time between preparation and measurement is reduced down to a few minutes and sample transfer through air is rigorously avoided.Temperature-dependent HESXRD measurements at temperatures up to 343 K were performed at beamline ID31 of the European Synchrotron Radiation Facility. The simultaneously measured electrochemical current and X-ray intensity indicate kinetic shifts in the charge transfer but a rather temperature independent Pt extraction process.We gratefully acknowledge financial support by the Deutsche Forschungsgemeinschaft via project no. 418603497 and the BMBF via 05K19FK3 and 05K22FK1.

Cu@Co with Dilatation Strain for High-Performance Electrocatalytic Reduction of Low-Concentration Nitric Oxide.

Electrocatalytic reduction of nitric oxide (NO) to ammonia (NH3 ) is a clean and sustainable strategy to simultaneously remove NO and synthesize NH3 . However, the conversion of low concentration NO to NH3 is still a huge challenge. In this work, the dilatation strain between Cu and Co interface over Cu@Co catalyst is built up and investigated for electroreduction of low concentration NO (volume ratio of 1%) to NH3 . The catalyst shows a high NH3 yield of 627.20µg h-1 cm-2 and a Faradaic efficiency of 76.54%. Through the combination of spherical aberration-corrected transmission electron microscopy and geometric phase analyses, it shows that Co atoms occupy Cu lattice sites to form dilatation strain in the xy direction within Co region. Further density functional theory calculations and NO temperature-programmed desorption (NO-TPD) results show that the surface dilatation strain on Cu@Co is helpful to enhance the NO adsorption and reduce energy barrier of the rate-determining step (*NO to *NOH), thereby accelerating the catalytic reaction. To simultaneously realize NO exhaust gas removal, NH3 green synthesis, and electricity output, a Zn-NO battery with Cu@Co cathode is assembled with a power density of 3.08mW cm-2 and an NH3 yield of 273.37µg h-1 cm-2 .

Electrolytic Reduction of UO2 Microspheres Synthesized Via Internal Gelation Method

Pyroprocessing is the combination of process steps to extract and recycle actinides from fission products in spent nuclear fuels in high-temperature molten salt media. Pyroprocessing has been studied extensively over the past decades. One of the key sub-processes is the electrolytic reduction of uranium oxides. The electrolytic reduction process originated from the FFC Cambridge process, an approach for electrochemically reducing titanium dioxide into titanium metal in molten CaCl2. In the electrolytic reduction of uranium oxides, the uranium oxide feed is applied as the cathode in LiCl-Li2O molten salt electrolyte at 650°C. LiCl appears more promising than conventional CaCl2 owing to the lower melting point (878 K), and higher decomposition voltage (3.46 V at 923 K). Additionally, Li2O is expected to speed up the reduction via an additional chemical reduction pathway with the participation of Li metal, and prevents the direct dissolution of the Pt anode.This work aims to study the morphology effect of the oxide feed on the reduction kinetics and the incorporation of impurities during the electrolytic reduction process. The electrolytic reduction of UO2 is carried out on sintered UO2 pellets, as well as various UO2 microspheres synthesized via internal gelation. The introduction of uranium oxide microspheres holds several advantages. The spheres provide a higher surface area, which is expected to improve the overall reduction efficiency of uranium oxide during electrolysis. In addition, it is easier to handle the feed during loading and unloading of the cathode basket compared to powder feeds.The potentiostatic and galvanostatic electrolysis of UO2 is performed, and the comparison between the electrolytic reduction of UO2 pellets and microspheres is investigated. The SEM micrographs in figure 1show the morphology change of a UO2 pellet to uranium metals particles. A significant morphology change between the flat surface of the sintered UO2 feed and the reduced U particles is observed at the surface. Further characterization is performed using XRD and TGA to identify the products of the electrolytic reduction process qualitatively and quantitatively. Results show that galvanostatic electrolysis shows a better reduction efficiency compared to potentiostatic electrolysis, applied both below and above the Li formation onset potential. Overall, there is barely un-reacted UO2 visible in the XRD patterns of the reduced feed after galvanostatic electrolysis. U metal and UO are identified in the XRD patterns depending on electrolysis parameters. The presence of UO can be as an intermediate of UO2 reduction during electrolysis, which is a rare compound to be reported in literature. Overall, the reduction of microspheres does improve the overall reduction efficiency compared to the conventional pellet feeds. Figure 1

(Invited) Controlling Metal Exsolution on Oxides By External Drivers – Role of Elastic Strain and Ion Irradiation

Exsolution is an effective approach to fabricating oxide-supported metal nanoparticle catalysts via phase precipitation out of a host oxide. A fundamental understanding and control of the exsolution kinetics are needed to engineer exsolved nanoparticles to obtain higher catalytic activity toward clean energy and fuel conversion. Since oxygen release via oxygen vacancy formation in the host oxide is behind oxide reduction and metal exsolution, we hypothesize that the kinetics of metal exsolution should depend on the kinetics of oxygen release. In this work, we probe the surface exsolution kinetics both experimentally and theoretically using thin-film perovskite oxide model systems, show its relation to the oxygen evolution kinetics. We also tune defect formation and the resulting metal exsolution, by external drivers including elastic strain and ion irradiation. Using both of these external drivers, we couple to the formation of point defects and defect clusters, that serve as nucleation sites for nanoparticle exsolution. As a result, we can controllably tune size, density, composition and position of the exsolved metal nanoparticles.

Dynamic Change in Throwing Power for the Cu-to-Carbon Steel Galvanic Couple in the Presence of Bentonite

In galvanic corrosion, the maximum distance from the periphery of the cathode to the anode is often defined as the throwing power. It dictates the surface area of the cathode involved in the galvanic corrosion and is also related to the extent of the accelerated anodic reaction. Therefore, its estimation is of great interest and importance in engineering applications, such as fastener and panel assembly [1], metal coatings [2], buried metallic structures [3], etc. Throwing power may be estimated experimentally by measuring the solution potential variation in close proximity to the electrode surface (Es) or through modelling, such as finite element analysis (FEA), provided the boundary conditions (polarization characteristics) are correctly determined. In this work, we investigated the throwing power for the Cu-to-carbon steel galvanic couple in the presence of bentonite clay, a scenario that could arise in the vicinity of a through-coating defect in the Canadian-designed nuclear waste container. Using a homemade micro-reference electrode array coupled to a Multichannel Microelectrode Analyzer (MMA), Es was measured simultaneously in 10 locations as a function of time in 0.1 M NaCl solution with and without bentonite clay, Fig. 1. Transient potential peaks were found when bentonite clay was added to the solution and are attributed to the increased galvanic activities driven by the reduction of air-formed Cu oxides.We further investigated this phenomenon using FEA. Boundary conditions were established experimentally under circumstances reflecting the actual surface states, i.e., with or without Cu oxides. Simulations were conducted considering secondary current distribution, using the appropriate boundary conditions. The obtained results match well with the experimental measurements, including the peak and the stable Es. Additionally, the dynamic change of the throwing power due to the evolution of the surface state was investigated through simulation and discussed. Reference [1] R.S. Marshall, A. Goff, C. Sprinkle, A. Britos, R.G. Kelly, Estimating the Throwing Power of SS316 when Coupled with AA7075 Through Finite Element Modeling, Corrosion, 76 (2020) 476-484.[2] J.R. Scully, F. Presuel-Moreno, M. Goldman, R.G. Kelly, N. Tailleart, User-Selectable Barrier, Sacrificial Anode, and Active Corrosion Inhibiting Properties of Al-Co-Ce Alloys for Coating Applications, Corrosion, 64 (2008) 210-229.[3] L. Liu, J. Li, M. Peng, W. Li, B. Lei, G. Meng, Macro-galvanic corrosion of tower grounding device consisting of graphite and Zn-coated steel in a simulated soil environment, Engineering Failure Analysis, 135 (2022) 106136. Figure 1

Organic Coating for Oxide Removal on Copper Surfaces

The oxidation of copper surface decreases the surface functional quality, which can be detrimental for several industrial applications. The objective of my research project is the one-pot reduction of copper oxides on copper surfaces, followed by the formation of a stable coating composed of organic molecules that prevent further oxidation. The organic coating will be deposited using four approaches: immersion, resonant acoustic mixing, vapor phase deposition, and electrochemical deposition. By applying mentioned deposition methods, preliminary tests were performed and further characterized by using X-ray photoelectron spectroscopy (XPS) and matrix assisted laser desorption ionization (MALDI), which confirmed the presence of organic molecules on the copper surface. To obtain best coating, optimization is being done by varying various parameters such as concentration of organic molecule solution, time of immobilization, solvent type and influence of temperature. After achieving an optimal coating, next step forward is to conduct bulk corrosion studies to understand the real effect of the coating. Protecting copper surfaces in such a manner can extend the lifetime of copper surfaces, thereby saving resources, time and money in target industrial applications. Figure 1

Nanoisland Formation on the Low Index Planes of Pt By Repeated Electro-Oxidation and-Reduction

Pt-based electro-catalysts are the most common cathode material in proton exchange membrane fuel cells given their high oxygen reduction reaction activity and stability. However, practical applications are limited by catalyst performance loss and degeneration. A main cause for this is nanoscale Pt surface restructuring, which occurs upon formation and reduction of a Pt surface oxide. During oxidation, a fraction of the Pt surface atoms are extracted in a process known as “place-exchange” from the electrode and are bound at specific sites in an oxide about 1 – 4 Å above the surface [1]. Upon subsequent oxide reduction, these atoms as well as the vacancies from which they originate can agglomerate, leading to the nucleation of adatom and vacancy islands. If this process is repeated, nanoislands with a well-defined lateral size of about 20 – 60 Å are grown [2-6]. Detailed studies of this growth process have been performed on the Pt(111) electrode [2-6], revealing two distinct growth regions which are characterized by different vertical scaling exponents [3].For the development of catalysts with superior long-term stability, a more detailed knowledge of the restructuring of the other low index planes of Pt is required. In our recent study of the Pt oxides on Pt(111) and Pt(100) we already showed a strong dependence of the structural stability of the surface on differences in the atomic-scale oxide structure formed on those two surface orientations [1]. However, the influence of surface structure on the nanoisland growth after repeated oxidation and reduction is largely unclear.We present a comparative operando grazing incidence small angle X-ray scattering (GISAXS) study of the nanoisland formation on Pt(111), Pt(100) and Pt(110) in acidic electrolyte. The GISAXS measurements of the nanoisland growth were performed at a high photon energy of >70 keV, which lowered background scattering from the electrolyte, enabling us to resolve the islands after the very first ox./red. cycle. Differences in island shape and growth behaviour on the low index planes will be discussed.We gratefully acknowledge financial support by the Deutsche Forschungsgemeinschaft via project no. 418603497, MA 1618/23-1 and the BMBF via 05K19FK3.References Fuchs et al., Nat. Catal. 3, 754–761 (2020)Sugawara and K. Itaya, J. Chem. Soc., Faraday Trans. 185, 1351-1356 (1989)Jacobse et al., Nat. Mater. 17 (3), 277-282 (2018)J. Rost, et al., Nat. Commun. 10, 5233 (2019)Ruge et al., J. Am. Chem. Soc. 139, 4532 (2017)Jacobse, et al. ACS Cent. Sci. 5 (12), 1920–1928 (2019)