Composite casting of aluminium onto steel is a promising technique for creating lightweight and durable hybrid materials, widely applicable in automotive and aerospace industries. A critical aspect is achieving a ductile bonding between aluminium and steel. Aluminium-silicon alloys can form highly ductile intermetallic phases with the iron substrate after a heat treatment. Thus, Al-Si alloys are interesting materials as fillers for steel parts instead of pure aluminium in composite casting (1). Electrodeposition offers an efficient and scalable means of producing such layers with tunable properties. The 1-ethyl-3-methylimidazolium chloride [EMIm]Cl: aluminium chloride [AlCl₃] ionic liquid provides a versatile medium for electrodeposition of Al and its alloys (2). Room temperature electrodeposition of Al-Si layers from this ionic liquid has already been demonstrated in the presence of different silicon precursors (3). The molar ratio between [EMIm]Cl and AlCl 3 defines the Lewis acidity of the resulting ionic liquid, directly influencing its suitability for electrodeposition. Electrolytes with a 1:1 ratio are referred to as Lewis neutral and with further addition of AlCl 3 , the electrolyte transitions to the Lewis acidic regime, where the acidity increases with an increase in AlCl 3 mole fraction. In this study we explored the relationship between the Lewis acidity of the electrolyte and electrochemical deposition of silicon. Potentiostatic experiments ranging from -0.2 V to -1 V vs Al/Al 3+ were conducted in [EMIm]Cl: AlCl 3 electrolytes having molar ratios between 1:1 and 1:2 with SiBr₄ as the Si source. Our findings showed that the amount of co-deposited silicon in the layers increases with decrease in Lewis acidity. Up to 19.3 wt.% of Si were deposited from a 1:1.3 [EMIm]Cl: AlCl 3 ionic liquid with 0.2 M SiBr 4 . While fine-grained compact aluminium layers could be deposited from electrolytes with higher Lewis acidity (such as 1:2), no silicon was co-deposited from this electrolyte at room temperature under our experimental conditions. Likewise, silicon could not be deposited from Lewis neutral (1:1) or Lewis basic (1: <1) ionic liquids. Furthermore, the introduction of agitation during electrodeposition did not result in silicon deposition as well, regardless of the Lewis acidity of the electrolyte. Our results demonstrate that the silicon content in deposits can be effectively tailored by controlling the electrolyte composition and deposition conditions. Acknowledgments: The authors gratefully acknowledge the financial support of the Federal Ministry for Economic Affairs and Climate Action, BMWK, Germany, within the project CastCo (FKZ 03LB2046E).

Composite coatings can show better behavior than the pristine metallic matrix in terms of wear and corrosion resistance, hardness, electrical conductivity, microstructure or brightness, just to name a few. Some important aspects for well-performing composite coatings are to reach a uniform distribution of particles in the metallic matrix, as well as avoiding the agglomeration of the particles in the electrolyte. This contribution presents recent results from authors’ labs on the influence of L-cysteine, N-acetylcysteine and thiourea on the electrodeposition of Zn-TiO 2 composite coatings in weakly acidic chloride-based electrolytes. We investigated the influence of the above additives on the morphology, microstructure and chemical composition (in terms of how many TiO 2 nanoparticles could be incorporated in the Zn matrix). The deposition process was monitored using in situ microgravimetry. Thus, we could determine the potential at which the deposition starts, the potential at which the dissolution sets in, as well as the current efficiencies and the deposition rates in the additive-containing electrolytes and compare them with the additive-free ones. The pure Zn electrolyte and the electrolyte containing only TiO 2 particles showed similar features and current densities in the cyclic voltammograms. Addition of L-cysteine inhibited the deposition rate and the dissolution process as proven by the lower current densities reached compared to the other electrolytes. Lower cathodic onset potentials of about 60 mV were needed in the presence of thiourea compared to pure Zn electrolyte. N-acetyl-L-cysteine showed a slightly inhibiting effect, less pronounced as the other two additives and lower deposition rates compared to the deposition rates in pure Zn electrolyte or in the electrolyte containing L-cysteine. The highest incorporation of titania particles was obtained in the presence of L-cysteine, followed by N-acetylcysteine.

Composite metal coatings with dispersed particles have gained significant attention in various industrial applications, including wear-resistant, corrosion-resistant, and heat-dissipating layers. By embedding particles within a metallic matrix, these coatings can enhance mechanical, thermal, and electrochemical properties, offering tailored functionalities for specific applications. Among these, composite aluminium-silicon coatings are particularly promising due to their lightweight nature, improved hardness, and thermal conductivity. However, optimizing the incorporation of Si particles within the aluminium matrix remains a key challenge, influenced by deposition conditions and particle characteristics. Electrodeposition serves as a versatile and cost-effective technique for producing such layers, enabling precise control over their composition, thickness, and morphology. In this study, we investigated the electrochemical deposition of composite aluminium-silicon layers using the ionic liquid electrolyte [EMIm]Cl : AlCl₃ at a molar ratio of 1:1.5. Two types of Si particles were examined: pure Si nanoparticles (100 nm) and highly doped Si microparticles (100 nm – 30 µm). The effect of deposition parameters such as current density, temperature, particle concentration, doping type, and light exposure on particle incorporation was systematically studied. Pure Si nanoparticles were added to the electrolyte in the range of 0.33 g/L to 5 g/L. Further increase in concentration led to increased electrolyte resistance. Despite ultrasonication, particles in the electrolyte existed mostly as agglomerates and got incorporated into the layers the same way. Pulse plating with varying duty cycles and frequencies showed no significant impact on particle incorporation. In contrast, galvanostatic deposition proved to be more effective, with higher current density and an increased bath temperature of 50°C leading to increased Si particle content in the layer. In case of highly doped Si microparticles, p and n-type were tested and concentrations up to 40 g/L did not increase the electrolyte resistance. Particles with p-doping were incorporated into the layer more effectively than n-type with up to 13.5 wt.% as opposed to 2 – 3 wt.% at 20 g/L. Additionally, higher bath temperatures improved particle incorporation, while the absence of ambient light reduced the amount of embedded Si particles in the matrix. These findings underline the critical role of bath temperature, particle doping type and deposition conditions in determining the Si particle content of the aluminium composite coatings. Acknowledgments: The authors gratefully acknowledge the financial support of the Federal Ministry for Economic Affairs and Climate Action, BMWK, Germany, within the project CastCo (FKZ 03LB2046E). Figure 1

Metals such as tantalum, titanium, niobium and their alloys cannot be deposited from aqueous solutions, due to their negative standard electrode potentials and the reactivity of their precursors with moisture and oxygen. This paper will present results from authors’ lab on the electrodeposition of the binary alloys obtained by combining two of the following elements: Ta, Ti and Nb. We will present why pristine Ta could be better deposited when a TaF 5 precursor is used, but pristine Nb reduction is easier when a NbCl 5 precursor is used. At the same time, when bromide precursors of the metals were used, their alloys could be deposited more easily. The complexing of Ta and Nb species in different ionic liquids was studied by Raman spectroscopy. The kinetics of the reduction process was studied by potential step experiments and rotating ring disc electrode. Diffusion coefficients were determined as a function of temperature and the type of ionic liquid used. Our results show that finding the right combination of precursor and the liquid that facilitates the reduction of Ta, Ti, Nb and their alloys, as well as the optimal technique for deposition (direct plating or pulse plating) can be a challenging task.

Simply expressed, the circular economy implies that the people living on Earth should reuse and recycle the products that are currently in use as long as possible and reduce the waste produced, thus reducing CO2 emissions. The latter goal is fundamental from the perspective of mitigating the well-known greenhouse effect and the consequent global warming observed at the planetary scale. Under these conditions, advanced electrodeposition processes can play a fundamental role in the optimization of materials use and in the reduction of the energetic footprint for a wide variety of industrial processes. The aim of the present paper is precisely to suggest how this is possible, showing readers the potential that electrodeposition holds for efficient manufacturing of many different products that have a huge significance for industry.

Cobalt-iron alloys are interesting soft magnetic materials which are used for example in magnetic sensors and transducers. They can be obtained by different techniques such as PVD, magnetron sputtering, or casting. One easy and not very expensive way to produce these alloys is the electrochemical deposition technique, which was also chosen in this study. This contribution will describe the electrodeposition of Co, Fe and Fe-Co alloys (Fe 70 Co 30 ) from an aqueous sulphate-based electrolyte containing boric acid as a buffer and sodium citrate and citric acid besides the metal sulphates. Potentiostatic step experiments and cyclic voltammetry were performed in parallel to electrochemical quartz crystal microbalance. Thus, we could identify the potential at which the deposition of the metals sets in, the mass of the deposited species as well as the current efficiency. We could also extract the partial current due to hydrogen evolution reaction and the partial current due to individual metal or their alloys from the total current density. The morphology and structure of the deposited films were investigated by means of SEM and XRD, respectively. The grain size of the deposits was calculated from the XRD data using Scherrer equation. Addition of citric acid to the electrolyte results in the smaller grain size of the deposited Fe-Co films.

Aluminum and its alloys are interesting materials for the automotive industry due to their relative low density compared to steel. The weight of vehicles can be drastically reduced by utilizing aluminum and its alloys in the construction of their body parts instead of steel. Moreover, we could previously prove in our group that some aluminum alloys, such as Al-Zn, showed improved resistance against corrosion compared to pure aluminum (1) when electrodeposited onto steel substrates. Aluminum-silicon alloys manufactured by casting have excellent mechanical properties and corrosion resistance. However, one of the problems that can occur during the cooling/solidifying phase in casting is the formation of micro- and macropores or the growth of Al-dendrites (2). An alternative technique to obtain Al-Si alloys is the electrodeposition technique. Due to the negative reduction potentials of both Al and Si, they cannot be electrodeposited from aqueous solution. They can be obtained by electrolysis in molten salt electrolytes at temperatures above 960°C (3). In this study we investigated the deposition Al-Si alloys at room temperature in 1-ethyl-3-methylimidazolium chloride, [EMIm]Cl: AlCl3 (1:1.5). Different precursors for Si such as SiCl4, SiBr4 and SiI4 were studied. We found that the type of precursor and its concentration influenced the maximum amount of Si in the alloy, as well as the morphology of the layers. Furthermore, the deposition technique (direct current plating or pulse plating) had a significant effect on the quality of the deposits. Acknowledgments: The authors gratefully acknowledge the financial support of the Federal Ministry for Economic Affairs and Climate Action, BMWK, Germany, within the project CastCo (FKZ 03LB2046E). R. Böttcher, A. Ispas, and A. Bund, Metals 13(2) (2023) 377 P.D. Lee, A. Chirazi, and D. See, J. Light Met. 1 (2001) 15 O. Awayssa, G. Saevarsdottir, R. Meirbekova, and G. M. Haarberg, J. Electrochem. Soc. 168 (2021) 046506

Al/Ni reactive coatings are fabricated via electrochemical deposition (ECD) at different applied voltages for reactive bonding application. AlCl3:1-Eethyl-3:1-ethyl-3-methylimidazolium chloride ([EMIm]Cl) (1.5:1) ionic liquid electrolyte is used as source of Al, whereas Ni is in the bath and incorporated into final coatings as nanoparticles (NPs). Scanning electron microscopy and Auger electron spectroscopy reveal a homogeneous Ni particle dispersion, as well as a high amount of particle incorporation into the Al matrix. A maximum of 37 wt% (22 at%) of Ni is detected via atomic absorption spectroscopy in the Al/Ni coating deposited at -0.1 V from an electrolyte containing 20 g L(-1 )of Ni NPs. Previous literature show that for bonding application an ideal concentration is around 50 at% of Ni and 50 at% Al. However, this is achieved using high vacuum, time-consuming processes, and costly techniques like evaporation and magnetron sputtering. The ECD used in this work represents a more cost-efficient approach which is not reported up to date for the aforementioned application. The reactivity of the coatings is confirmed by Differential scanning calorimetry. Herein, an exothermic reaction is detected upon the mixing of Al and Ni occurring at high temperatures.

Al/Ni reactive coatings are fabricated via electrochemical deposition (ECD) at different applied voltages for reactive bonding application. :1‐ethyl‐3‐methylimidazolium chloride ([EMIm]Cl) (1.5:1) ionic liquid electrolyte is used as source of Al, whereas Ni is in the bath and incorporated into final coatings as nanoparticles (NPs). Scanning electron microscopy and Auger electron spectroscopy reveal a homogeneous Ni particle dispersion, as well as a high amount of particle incorporation into the Al matrix. A maximum of 37 wt% (22 at%) of Ni is detected via atomic absorption spectroscopy in the Al/Ni coating deposited at −0.1 V from an electrolyte containing 20 g L −1 of Ni NPs. Previous literature show that for bonding application an ideal concentration is around 50 at% of Ni and 50 at% Al. However, this is achieved using high vacuum, time‐consuming processes, and costly techniques like evaporation and magnetron sputtering. The ECD used in this work represents a more cost‐efficient approach which is not reported up to date for the aforementioned application. The reactivity of the coatings is confirmed by Differential scanning calorimetry. Herein, an exothermic reaction is detected upon the mixing of Al and Ni occurring at high temperatures.

The electrodeposition of tantalum-titanium–based films using different tantalum and titanium halides was investigated in two ionic liquids, namely, 1-butyl-1-methylpyrrolidinium bis (trifluoromethyl-sulfonyl)imide ([BMP][TFSI]) and 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate ([BMP][OTf]). Cyclic voltammetry was used to analyse the electrochemistry of the electrolytes and potentiostatic deposition was performed to evaluate the feasibility of electrodepositing tantalum-titanium–based layers. Both the metal salts and the ionic liquid influenced the electrochemical reduction of the tantalum and titanium halides significantly. While titanium halides considerably retarded the reduction of tantalum pentahalides and inhibited electrodeposition in many electrolytes, an electrolyte composition from which tantalum and titanium-containing layers could be deposited was identified. Specifically, in TaBr 5 and TiBr 4 in [BMP][TFSI], TiBr 4 did not inhibit the deposition of tantalum and titanium was co-deposited itself by a three-step reduction mechanism as confirmed by cyclic voltammetry and energy-dispersive X-ray spectroscopy. Furthermore, [BMP][TFSI] led to smoother and more compact deposits.

Pulse plating is often used to improve the morphology of deposits. One can thus electrodeposit films with finer grains and lower roughness, more compact layers by pulse plating than by direct current methods. In some cases, the throwing power and/or the adhesion of the deposits to the substrates can also be improved. Pulse plating is widely used in industry for aqueous electrolytes, but it is not largely employed in ionic liquids (ILs). Tuning the parameters for pulse plating, such as the frequency and the duty cycle can be challenging due to the very different properties of ILs compared to most molecular solvents. Besides the pulse parameters, the effect of temperature can be rather strong, as ILs have a relatively high viscosity and thus lower conductivity. An increase in temperature will facilitate the mass transport. Further physical-chemical properties of ILs play also an important role in pulse plating applications, e. g. their double layer structure. This paper will describe results from authors' lab on the electrodeposition of alloys in ILs. The feasibility of electrodepositing of binary alloys of Ta, Ti and Nb was investigated by varying the pulse parameters besides the types of metal salts (chloride or bromide) and ILs and temperature. Better layers in terms of morphology and purity were obtained by pulse plating techniques compared to direct current deposition. To the best of the authors' knowledge pure titanium cannot be electrodeposited from ILs, but 9-15 wt% could be co-deposited with tantalum in 1-butyl-1-methylpyrrolidinium bis(tri-fluoromethylsulfonyl)amide. Challenges remain with the optimization of the pulse parameters to tune the composition of the alloys and to minimize the incorporations of impurities.

Today's requirements in the art field have challenged researchers to create artistic paintings with attractive appearance and long-term color stability. Alkyd-based art mediums have become an important group in the art field, because of their similar characteristics to traditional oils and exceptional drying properties. In this work, high solid alkyd-based art mediums have been synthesized by the monoglyceride and acidolysis processes. Multifunctional polyols and high unsaturated fatty acid sources were compared and used for alkyd synthesis. The use of a non-traditional oil of Peruvian origin is proposed. Resins have been characterized according to their physicochemical (acid number, viscosity, color and density) and drying properties. Drying tendencies were verified with the use of quartz crystal microbalance. Also, the behavior of the art mediums mixed with commercial oil paintings and a dry pigment, have also been evaluated. Results indicate that resins containing the polyol with the highest functionality are more viscous and have fewer tendencies to yellowing, while non-traditional Peruvian oil is the best option for creating light-colored art mediums. Alkyd mediums prepared by the monoglyceride method gave to oil paintings better characteristics and drying behavior on canvas.

This article reports a new approach toward fabrication and directed assembly of nanoparticulate reactive system (Nanofoils) on patterned substrates. Different from current state-of-the-art, gas phase electrodeposition uses nanoparticles instead of atoms to form densely packed multilayered thin films at room temperature-pressure. On ignition, the multilayer system undergoes an exothermic self-propagating reaction. The numerous contact points between two metallic nanoparticulate layers aid in high heat release. Sub-10-nm Platinum (Pt) and Aluminum (Al) particles are synthesized through cathode erosion of metal electrodes in a flow of pure nitrogen gas (spark ablation). Pt/Al bilayer stacks with total thickness of 3–8 µm undergo self-propagating reaction with a 10.3 mm s −1 wavefront velocity on local ignition. The reaction wavefront is captured using high speed videography. Calorimetry studies reveal two exothermic peaks suggesting Pt/Al alloy formation. The peak at 135 °C has a higher calorific value of 150 mW g −1 while the peak at 400 °C has a 12 mW g −1 exothermic peak. X-ray diffraction study shows reaction-products are cubic Al 2 Pt with small quantities of orthorhombic Al 6 Pt and orthorhombic AlPt 2 . Electron microscopy studies help draw a correlation between film morphology, bimetallic interface, nanoparticle oxidation, and self-propagating reaction kinetics that is significant in broadening our understanding towards nanoparticulate reactive systems.

Aluminum cannot provide continuous cathodic corrosion protection under ambient conditions due to the formation of an insulating oxide layer and therefore it should be alloyed. Binary aluminum alloys with Cr, Zn and Sn from AlCl3/1-ethyl-3-methylimidazolium chloride ([EMIm]Cl) containing CrCl2, ZnCl2 or SnCl2 have been deposited and their morphology and composition were investigated using SEM/EDS. The corrosion behavior of alloys with 2–4 wt% Cr, Zn or Sn was investigated using potentiodynamic polarization in 3.5 wt% NaCl solution, neutral salt spray test (NSS) and environmental exposure (EE). Pure aluminum provides excellent corrosion protection of steel in a chloride-containing environment, but not under ambient conditions. AlCr alloys show poor corrosion protection while AlZn alloys provide excellent corrosion protection in the NSS test and superior cathodic protection in the EE test compared to aluminum. AlSn alloys are highly active at even low tin contents and dissolve rapidly in chloride-containing electrolytes. However, a slightly improved cathodic protection in the EE test compared to pure aluminum has been observed. The results prove the necessity of alloying aluminum to achieve effective cathodic corrosion protection under mild atmospheric conditions.

This article reports a new approach toward fabrication and directed assembly of nanoparticulate reactive system (Nanofoils) on patterned substrates. Different from current state-of-the-art, gas phase electrodeposition uses nanoparticles instead of atoms to form densely packed multilayered thin films at room temperature-pressure. On ignition, the multilayer system undergoes an exothermic self-propagating reaction. The numerous contact points between two metallic nanoparticulate layers aid in high heat release. Sub-10-nm Platinum (Pt) and Aluminum (Al) particles are synthesized through cathode erosion of metal electrodes in a flow of pure nitrogen gas (spark ablation). Pt/Al bilayer stacks with total thickness of 3-8 & mu;m undergo self-propagating reaction with a 10.3 mm s(-1) wavefront velocity on local ignition. The reaction wavefront is captured using high speed videography. Calorimetry studies reveal two exothermic peaks suggesting Pt/Al alloy formation. The peak at 135 & DEG;C has a higher calorific value of 150 mW g(-1) while the peak at 400 & DEG;C has a 12 mW g(-1) exothermic peak. X-ray diffraction study shows reaction-products are cubic Al2Pt with small quantities of orthorhombic Al6Pt and orthorhombic AlPt2. Electron microscopy studies help draw a correlation between film morphology, bimetallic interface, nanoparticle oxidation, and self-propagating reaction kinetics that is significant in broadening our understanding towards nanoparticulate reactive systems.

The electrodeposition of reactive aluminum-nickel dispersion coatings was performed by pulsed direct current (PDC) onto copper substrates in the ionic liquid 1.5:1 AlCl3:[EMIm]Cl (1-Ethyl-3-methylimidazolium chloride). A cathodic current density of 15 mA/cm2 was used with two different frequency (f)/duty cycle (r c) combinations, i.e., f= 0.33 Hz/ r c= 0.33 (t on= 1 s, t off= 2 s) and f= 0.05 Hz/ r c= 0.5 (t on= 10 s, t off= 10 s). Several electrochemical techniques like Cyclic Voltammetry, Electrochemical Impedance Spectroscopy and Open Circuit Potential measurements were used besides X-Ray Diffraction, Confocal Microscopy, Scanning Electron Microscopy, Atomic Absorption Spectroscopy and 27Al/1H Nuclear Magnetic Resonance in order to shed more light on the mechanism of Ni particle incorporation into the Al metal matrix. We could show that particle incorporation at the beginning of the deposition mainly takes place via particle adsorption at the substrate. As the thickness of the coating increases, it seems that the main mechanism for particle incorporation is via the reduction of Al2Cl7 - ions adsorbed at the particles surface. Three different Ni NPs concentration were tested in this work: 5, 10 and 20 g/L. Although a considerable high incorporation of Ni NPs has been achieved from the IL electrolyte containing the highest concentration of Ni NPs (i.e. ~ 33 wt.% from a 20 g/L of Ni NPs bath), a high concentration of NPs in the ionic liquid resulted having a negative effect in terms of quality of the coatings, due to local cathodic passivation, or solidification of the electrolyte in a poorly conductive compound. This phenomenon has been related to the increase in viscosity originating from the decrease in rotational mobility of the [EMIm]+ cation, as detected by 1H NMR. Despite this fact, almost equivalent amounts of Ni and Al (Ni ~ 45 wt.% and Al ~ 44 wt.%) have been detected by energy-dispersive X-ray spectroscopy mapping in some areas of the coatings prepared with longer pulse off-time (f = 0.05 Hz, t off= 10 s). Such a layer composition would be convenient for the targeted application. Nevertheless, more studies related to the homogeneity of the deposits, as well as ignition tests, must be performed to evaluate the suitability of the coatings to trigger a self-propagating reaction.

This paper will present recent results from the authors’ labs on electroformed aluminum based composite films from room temperature chloroaluminate melts. Although the research field of aluminum electrodeposition has been very active, there are still numerous scientific and technical challenges to be addressed, such as minimization of the incorporation of impurities in the films. This contribution will discuss the new process of composite electroplating [1,2] for the production of ultra power dense cathodes for lithium-ion batteries. Electrode foils consisting of an aluminum matrix with particles of different active materials have been prepared by composite electroforming. The aim is to reduce the number while improving the properties of electrode components for lithium ion batteries, that will finally promise very high-power densities and cell efficiencies for these batteries, e.g. by reducing internal resistances. Here we will discuss the design of the electroforming process, as well as the characterization of the battery cathodes. [1] C. Erhardt, Ș. Sörgel, S. Meinhard, T. Sörgel, J. Power Sources 2015, 296 , 70-77 [2] T. Sörgel, S. Meinhard, Ş. Sörgel, Film Composite Material, EP 3114721 B1, 2015

Electropolishing is widely used industrially to create smooth and bright surface finishings. This technique is particularly relevant for components with complex geometries, especially in the onset of additive manufacturing. (1, 2) As E. J. Taylor showed for different types of materials, pulse techniques can be used to control the surface modification and drive the electrochemical process towards a specific desired result. (3) The changes in the surface layers and concentration profiles caused by shifts in polarization lead to results difficult to attain in constant current/potential conditions, especially in metals that passivate and alloys containing metals with dissimilar electrochemical stabilities. Titanium and noble metal-alloys are materials used in a variety of applications. The passivation layer of titanium is very difficult to remove without using strong acids or fluoride-containing compounds. In the case of noble-metal alloys, the problem lies in the non-uniform dissolution of the material under anodic polarization and in the cyanide-containing electrolytes and strong acids which are used for electropolishing. Water-free solvents have been described by Jacquet for this purpose (4). Ionic liquids and deep eutectic solvents, DES, are increasingly being used to work in potential windows otherwise not reachable in aqueous solutions. Reports indicate that a mixing of choline chloride and ethylene glycol can be used for electropolishing of titanium and other metals (5, 6) and that both dissolution and recovery of Au and Pd is feasible in ionic liquids and deep eutectic solvents. (7, 8) Using DES for electropolishing applications offers therefore an opportunity to substitute dangerous substances, such as cyanide and fluoride compounds. This could increase the scope of application of electropolishing in terms of work safety, recycling and disposal. The aim of this work is to show the interplay between pulse parameters (frequency, pulse height and reverse pulses) and the viscosity of the solution. Together with temperature and convection, pulses can be used to selectively control the dissolution of the metal towards the desired surface finish. Using this principle, an average roughness of 20-30 nm was achieved for titanium samples with complex geometry, both under laboratory conditions as well as in a pilot plant. Furthermore, it will be shown how pulses can be used to control the dissolution of electrochemical less noble elements in gold alloys. Acknowledgements: The project is financially supported by the German Federal Ministry for Economic Affairs and Climate Action (ZIM Program). References W. Han and F. Fang, International Journal of Machine Tools and Manufacture, 139, 1–23 (2019). E. J. Taylor, H. McCrabb, H. Garich and T. Hall, A pulse/pulse reverse electrolytic approach to electropolishing and through-mask electroetching PF Products Finishing, Electroplating, www.pfonline.com (published on 26.09.2011). E. J. Taylor, M. Inman, T. D. Hall, S. Snyder, J. Mammosser and F. Furuta, ECS Meet. Abstr., vol. MA2017-01(24), 1197 (2017). P. A. Jacquet, Trans. Electrochem. Soc., 69(1), 629 (1936). W. O. Karim, J. A. Juma, K. M. Omer, Y. M. Salih, K. H. Aziz and S. B. Aziz, Electrochemistry, 88(5), 447–450 (2020). A. P. Abbott, G. Frisch, J. Hartley, W. O. Karim and K. S. Ryder, Progress in Natural Science: Materials International, 25(6), 595–602 (2015). E. Billy, E. Chainet and F. Tedjar, Electrochimica Acta, 56(28), 10340–10346 (2011). P. Giridhar, K. A. Venkatesan, B. P. Reddy, T. G. Srinivasan and P. R. Vasudeva Rao, Radiochimica Acta, 94(3), 131–136 (2006).

The speciation of Cr, Zn and Sn in AlCl3/1-ethyl-3-methylimidazolium chloride containing CrCl2, ZnCl2 and SnCl2, respectively, has been studied by cyclic voltammetry (CV), Raman spectroscopy and density functional theory (DFT) calculations. Addition of the respective metal salt causes the current waves in the CV to decrease, indicating a reaction of the metal salts with Al2Cl7 −. Compared to the neat electrolyte, the Raman peaks of Al2Cl7 − decrease while the AlCl4 − peak increases in intensity, broadens and shifts towards lower wavenumbers. Calculated wavenumbers of metal complexes [Me(AlCl4)3]− reflect these observations. DFT calculations of the Gibbs free energies of formation, solvation and reaction support the formation of the proposed complexes. The central ions are coordinated by three bidentate AlCl4 − ligands that are arranged planar–trigonally. Due to the occupied Sn–5s orbital, repulsive forces cause a trigonal–pyramidal geometry in case of the Sn complex. Based on the similarities in the experimental observations and the orbital configuration of Zn2+ compared to Cr2+, the spontaneous formation of the species [Cr(AlCl4)3]− can be assumed.

An inorganic-framework molecularly imprinted NiAl layered double hydroxide (MI-NiAl-LDH) with specific template molecule (glyphosate pesticide, Glyp) recognition ability was prepared on Ni nanorod arrays (Ni NRAs) through electrodeposition followed by a low-temperature O2 plasma treatment. The freestanding Ni/MI-NiAl-LDH NRA electrode had highly enhanced sensitivity and selectivity. The electrocatalytic oxidation of Glyp was proposed to occur at Ni3+ centers in MI-NiAl-LDH, and the current response depended linearly on the Glyp concentration from 10.0 nmol/L to 1.0 μmol/L (R2 = 0.9906), with the limit of detection (LOD) being 3.1 nmol/L (S/N = 3). An exceptional discriminating capability with tolerance for other similar organophosphorus compounds was achieved. Molecular imprinting (N and P residues) affected the electronic structure of NiAl-LDH, triggering the formation of highly active NiOOH sites at relatively lower anodic potentials and substantially enhancing the electrocatalytic oxidation ability of the NiAl-LDH interface toward the C-N bonds in Glyp. In combination with the surface enrichment effect of MI-NiAl-LDH toward template molecules, the electrochemical oxidation signal intensity of Glyp increased significantly, with a greater peak separation from interfering molecules. These results challenge the common belief that the excellent performance of inorganic-framework molecularly imprinted interfaces arises from their specific adsorption of template molecules, providing new insight into the development of high-performance organic-pollutant-sensing electrodes.