bluuebunny/crossref_metadata_2025 huggingface dataset:
Laser Assisted Electrodeposition of Metals and Alloys
Authors: Bernasconi Roberto , Crimella Dario , Demir Ali Gokhan , Previtali Barbara , Magagnin Luca
Published: February 2024

Laser sources are extensively used in surface engineering technology and in materials processing. Their high energy density, excellent directionality and monochromaticity makes them ideal for a wealth of potential uses that require the concentration of a significant amount of energy in a small area. From the electrochemical point of view, one of the most interesting applications for lasers is Laser Assisted Electrodeposition (LAE). Indeed, the high energy density transferred by a laser can locally change the electrochemical state of a surface by inducing photo-electrochemical or thermal-electrochemical effects, triggering thus metal reduction. In addition, it is also possible to pattern the deposited metal layer by scanning the surface of the substrate with the laser, usually with spatial resolution in the range of few micrometers. From the applicative point of view, LAE can be exploited for the selective deposition of metal layers for both decorative and functional uses.

LAE can be intended in two ways: the laser can be used to enhance a standard electrolytic deposition process [1, 2], increasing deposition rates by focusing the radiation on the cathode, or it can be used to trigger electrodeposition on freestanding metal surfaces in total absence of any external polarization [1]. The latter approach is the most interesting due to the reduced complexity of the setup required and is made possible by the localized variation of the rest potential induced in the zone of the substrate hit by the light [1]. As a consequence of this variation, metallic ions can be reduced in correspondence of the illuminated zone. The occurrence of this phenomenon, which allows metal deposition without any external power source, has been demonstrated for Cu [1, 3], Ni [3] and Au [4].

Despite the work carried out by many research groups, still many aspects of LAE in absence of external polarization remain poorly understood. The aim of the present work is to investigate the possibility to perform LAE with some significant metal-substrate couples. The deposition mechanism is rationalized considering the specific electrochemical properties of the metals involved. In addition to this fundamental characterization, the work also aims at evaluating the industrial applicability of LAE. To this extent, patterned layers of precious metals are deposited on metallic substrates for decorative purposes. Finally, LAE is applied here for the first time to the deposition of alloys.

[1] J. C. Puippe et al., J. Electrochem. Soc. 128(12), 2539-2545 (1981)

[2] Z. Zhang et al., MDPI Materials 13, 3560 (2020)

[3] R. J. von Gutfeid et al., IBM J. Res. Develop. 26(2), 136-144 (1982)

[4] Khan et al., NASF Surface Technology White Papers 84(3), 6-13 (2019)
Pulse-Electrodeposition and Growth Mechanism of Nanotwinned Copper Nanowires inside High Aspect-Ratio Anodic Aluminum Oxide
Authors: Chen Hsin-Yu , Liao Chien-Neng
Published: February 2024

Nanotwinned copper (nt-Cu) has proven to possess many fascinating physical/chemical properties. However, it is still challenging to control the twin density and its orientation especially for high aspect-ratio Cu vias. Here, a matrix of nt-Cu nanowires (aspect ratio > 150) with dense coherent twin boundaries (CTBs) perpendicular to the growth direction were deposited in porous anodic aluminium oxide vias by pulse electrodeposition. We changed the pulse on/off duration to control the degree of (111) growth texture and twin density of the nt-Cu nanowires. A small anodic current in the pulse-off period enhanced (111) crystal texture and CTB formation during the bottom-up filling process. With the analysis of twin density, we proposed that the nanoscale twinning was activated by facet-dependent crystal growth and stress accumulation/relaxation behaviour during pulse electrodeposition. The interplay between on/off period and bias potential could modulate the twin density. Also, the sulfate adsorbates were proved to play an important role in the stress accumulation process. This study could be implemented in fabricating Cu interconnect in nanoelectronic devices and nanoelectromechanical systems.

Figure 1
Influence of High Surfactant Concentrations on the Morphology and Crystallinity of Electrodeposited Antimony and Bismuth Nanowires
Authors: Wagner Michael Florian Peter , Hsun Lin Kuan , Sigle Wilfried , Trautmann Christina , Toimil Molares Maria Eugenia
Published: February 2024

Antimony and bismuth nanowires are excellent model systems to investigate the interplay of various size-dependent transport phenomena relevant for applications in thermoelectrics, spintronics, or catalysis. The properties of these nanowires can be significant influenced by size effects due to the large mean free path and Fermi wavelength of charge carriers and phonons. Since antimony and bismuth possess highly anisotropic Fermi surfaces, the transport is also strongly dependent on the crystallographic orientation. Therefore, it is very important to develop and control suitable electrodeposition processes that allow us to understand the nanowire growth and to accordingly adjust preferred orientation and morphology of the synthesized nanowires.

The so called template route employed in the presented work allows to control number density, alignment, geometry, length and diameter of the nanowires. The electrolytes and plating processes influence crystallinity, crystal orientation, and morphology of the electrodeposited materials. Here, antimony and bismuth nanowires are grown by potentiostatic electrodeposition in polycarbonate etched ion-track membranes using SbCl3 and BiCl3 in aqueous electrolytes.

In this talk, we will show the influence of the presence of nonionic and anionic surfactants in high concentrations in the electrolyte during the electrodeposition of Bi and Sb nanowires. The recorded current-time curves of the plating process will be presented. Systematic characterization of the nanowires by scanning- and transmission electron microscopy, and X-ray diffraction reveal a strong change in crystallinity as a function of surfactant concentration, which will be discussed in detail.
Application in Self-Adsorption Pd Nanoparticles with High Adhesion
Authors: Wei Pei-Tsen , Wei Tzu Chien
Published: February 2024

Electroless plating (ELP) is widely used to metallize non-conductive substrates in printed circuit board industry. Due to the complexity of commercial palladium catalysts activation procedure and the high price of palladium, we synthesized a type of palladium catalyst with polyvinyl alcohol (PVA) as protector, formaldehyde (HCHO) as reducing agent. We used polyethylimine (PEI) to modify the surface of the substrate in advance.

In this study, we developed a one-step catalyst by adding PEI into PVA-Pd. In addition to its stability, the catalyst has self-adsorption property. The process can be operated at low concentrations, which can effectively reduce the cost. Because of these characteristics, it can not only control the catalyst better than the commercial palladium catalyst but also simplify the process. The effect of self-adsorption was tested on Rogers RO3003 laminates. RO3003 high frequency laminates are ceramic-filled PTFE composites for use in printed circuit boards in commercial microwave and RF applications. The substrate has excellent characteristics such as stable dielectric constant over various temperatures and frequency and low coefficient of thermal expansion. Due to these properties, RO3003 has a great potential to be applied in 5G generation products. After activating, we used electroless copper plating to metallize the substrate.

The study focused on the Cu/Pd ratio of the self-adsorption catalyst PEI+PVA-Pd to quantitatively analyze the adsorption capacity by ICP-OES, and the adhesion was analyzed by T-peel. The results indicates that the process is cost-effective, and the adhesion between substrate and copper foil is also higher. The copper layer by using self-adsorption catalyst will also have a better compactness and the surface will be pinhole-free. Therefore, this process can be successfully applied to electroless copper deposition with self-adsorption catalysts.
Local Heating Induced Single-Crystalline Phase Control in Electrochemical Synthesis of Nanomaterials
Authors: Lee Myoungwon , Ahn Hyun
Published: February 2024

Synthesis of electrochemical crystalline nanomaterials have a great advantage. The single crystalline material synthesized by the existing solvothermal synthesis method often has no catalytic activity due to contamination on the surface during the synthesis process. Therefore, in this study, the electrochemical single crystalline nanomaterials induced by heat were clearly synthesized. Since a process of thermal post-treatment of nanomaterials require a high temperature, thermal induced electrochemical synthesis was lowering the thermal energy barrier.

In this study, copper, silver, gold, and platinum single crystalline nanoparticles were synthesized and characterized through SEM, TEM, and SAED. In the synthesis process, the growth process according to deposition coulomb was observed. And the catalytic activity of the synthesized single crystalline nanomaterials was measured.
(Invited) High-Throughput Local Electrochemistry Coupled with (in-situ) microscopy to Advance on the Fundamentals of Electrochemical Nucleation and Growth
Authors: Ustarroz Jon , Torres Daniel , Bernal Lopez Miguel , Parpal Gimenez Monica , El Marini Mohamed , Chemchoub Sanaa , Bertolucci Coelho Leonardo
Published: February 2024

Electrochemical nucleation and growth (EN&G) are the cornerstone for many (nano)material growth routes and the main factor limiting battery durability. The in-depth experimental assessment of the process is very challenging due to the random nature of initiation events (nucleation), the heterogeneity of surfaces and the (very) fast kinetics across several length scales. For all that, our understanding of the mechanisms involved is inaccurate and incomplete [1].

During the last years, we have developed an approach based on using carbon coated TEM grids as electrodes to combine ex-situ atomic-scale TEM characterization with electron tomography and macroscale electrochemical measurements [2,3]. This approach has brought valuable evidence of non-classical growth pathways such as growth mediated by nanocluster aggregation [3,4]. Yet, it does not capture the influence of the heterogeneous nature of the surface where EN&G proceeds, nor the dynamics before, during and after nucleation [5].

In this contribution, we present our recent work in which we combine high-throughput local electrochemistry by Scanning Electrochemical Cell Microscopy (SECCM), with ex-situ and in-situ characterization, including electrochemical transmission electron microscopy (EC-TEM), to study the electrochemical nucleation and growth of metals on carbon surfaces [6,7].

The spatially resolved electrochemical characterization enables a one-to-one correlation between the electrochemical data and the local surface properties, which can be evaluated by different surface analytical tools (SEM, AFM, ...) in identical locations to where the local electrochemical measurements have been performed. In addition, EC-TEM allows the study of the early-stage growth/dissolution dynamics of the metallic phase.

The combination of both methods opens new opportunities for fully understanding the complex nature of EN&G phenomena. In the longer run, this can be exploited for the rational design (electrodeposition) of functional nanostructured materials considering the heterogeneous nature of the supports and the differences within nanomaterial ensembles.

References:

[1] Ustarroz, J. Current Opinion in Electrochemistry 19, 144–152 (2020).

[2] Ustarroz, J et al. Journal of the American Chemical Society 135, 11550–11561 (2013).

[3] Ustarroz, J et al. The Journal of Physical Chemistry C116, 2322–2329 (2012).

[4] Hussein H. E. M. et al., ACS Nano 12, 7388–7396 (2018).

[5] Harniman R. L. et al., Nature Communications 8, 971 (2017).

[6] Bernal, M. et al. Electrochimica Acta 445, 20, 142023 (2023).

[7] Torres, D. et al. Journal of the Electrochemical Society 169, 102513 (2022).
The Enigma of Titanium Electrodeposition on Various Substrates
Authors: Lal Sudarshan
Published: February 2024

Titanium is an oxiphilic reactive metal which readily forms passive oxide films onto substrates. The unique properties of the metal such as low density (d=4.5 g/cm3), high strength, and corrosion resistance in harsh environments offers practical advantages. The pure metal is used abundantly in aerospace, armors, submarines, missiles, biomedicals, golf clubs and special electronic applications. The electro-deposition of corrosion resistant coatings is imperative to protect base metals. A review of previous literature has indicated that methods such as roll-diffusion cladding, magnetron discharge sputtering, electron beam, vacuum evaporation, ion beam enhanced deposition (PVD), thermal spray, chemical conversion coatings etc. have been employed in special applications at a prohibitive cost. Plating of titanium films in molten salts at high temperature, and inert atmospheres is a challenge to follow stringent conditions. Electroplating in ionic liquids is extremely expensive and limited.

It will be an important technological advancement if a feasible electrodeposition process for titanium is developed for light base metals and plastics in aqueous or semi-aqueous solutions. Titanium electrodeposition in aqueous systems is not a straight-forward process due to its far negative reduction potential than that of hydrogen. Its multivalence states, stability, limited potential range, gas evolution, and substrate passivation pose technical challenges. The present author has critically evaluated several recipes cited by Russian literature, and a few United States patents. Unfortunately, we could not substantiate their cited claims. We have developed an innovative and proprietary process for electro-deposition of Ti in aqueous and partially non-aqueous systems. Deposition of titanium and its alloy films is demonstrated on variety of substrates such as Steel, Pb, Zn, Al, and selected plastics. It is our hope that this endeavor will open new avenues in surface finishing applications.
Study of Structural Morphology of Electrodeposited Ni Film
Authors: Mubshrah Ayesha , Schwarzacher Walther
Published: February 2024

Structural morphology of thin electrodeposited metallic films plays a vital role in determining the properties of the films and their application. We prepared a range of Ni electrodeposited polycrystalline films using a BIOLOGIC potentiostat and investigated the effects of varying parameters such as the deposition rate and concentration of the solution to improve control over their properties. We conducted analysis of surface morphology of thin films of area 1cm2, as well as at microstructural level of area 50x50 um2, using ex-situ AFM and in-situ HS AFM. Ex-situ AFM data helps us to do quantitative surface analysis, including slope, scaling analysis [1] and grain area calculation as a function of time, concentration, and applied potential. HS AFM provides us with information about the grain structure evolution at microstructural level [2]. The texture of films was determined by XRD analysis. For the thin films, Ni[111] orientation was dominant, but for thick films, the dominant crystallographic orientations was Ni[200].We also performed EBSD analysis for Ni thin films after milling with focused ion beam. EBSD uses backscattered electron to obtain the information of structural morphology and crystallographic orientation of thin films layer by layer. The correlation between ex-situ AFM and EBSD data helps to gain a clear understanding of the structural features of the films.

Liu, L., & Schwarzacher, W. (2013). Slope analysis and scaling analysis of electrodeposited thin films. Electrochemistry communications, 29, 52-54.

Koorikkat, A., Payton, O., Picco, L., & Schwarzacher, W. (2020). Imaging the Surface of a Polycrystalline Electrodeposited Cu Film in Real Time Using In Situ High-Speed AFM. Journal of the Electrochemical Society, 167(16), 162510.
Electrochemical Deposition Processes for Fabrication of Cathodes/Anodes of Alkaline Water Electrolysis Device
Authors: Kunimoto Masahiro , Fukunaka Yasuhiro , Ito Hiroshi , Homma Takayuki
Published: February 2024

Water electrolysis employing anion exchange membranes (AEM) is a promising technique toward the realization of a carbon-neutral society as it facilitates the development of water electrolyzers without noble metals; generally, alkaline electrolytes do not require platinum and iridium oxides for catalysts or titanium for porous transport layers (PTL) and bipolar plates. Although coating techniques have been demonstrated to be effective in forming catalyst layers of cathodes or anodes with lowered resistances [1,2], in this paper, the authors present novel electrochemical methods to produce cathodes/anodes to be used in AEM water electrolysis devices.

In the fabrication of cathodes, we use electroless deposition for the direct formation of non-noble metal alloy catalysts on the AEM. This enables ionomer-less attachment of the catalyst layer on the membrane, producing a catalyst that is sufficiently durable under high temperatures. Here, pretreatments for activating the membrane before the deposition are critical. Based on quantum chemical calculations, we found that immersing the membrane in a solution of palladium chloride, prior to its immersion in a reducing agent solution, provides sufficiently stable catalyst nuclei for electroless deposition.

For the fabrication of anodes, electrolytic deposition of the catalyst on a PTL is chosen. To retain the porous structure of the PTL, the deposition of a compact film is essential. For this, pulse electrodeposition with an optimized sequence of current density is an attractive technique as it accomplishes metal deposition while retaining the substrate shape. Scanning electron microscopy images in this study proved that the pulse sequence of the current density is beneficial to depositing catalyst alloys with the porous structure of the PTL retained. This is because the pulse technique recovers the depletion of precursor ions for deposition around the electrode surface, which results in preventing the development of diffusion layers. We expect that these processes will make alkaline water electrolysis devices more efficient and cost effective.

[1] H. Ito, N. Miyazaki, S. Sugiyama, M. Ishida, Y. Nakamura, S. Iwasaki, Y. Hasegawa, A. Nakano, J. Appl. Electrochem., 48, 305 (2018).

[2] H. Ito, N. Kawaguchi, S. Someya, T. Munakata, N. Miyazaki, M. Ishida, A. Nakano, Int. J. Hydrogen Energy, 43, 17030 (2018).

Acknowledgements

This study was financially supported in part by the “Advancement of Hydrogen Technologies and Utilization Project” from the New Energy and Industrial Technology Development Organization (NEDO) of Japan. We would like to express the gratitude to Tokuyama Corporation for the supply of AEM.
Metal/Metal Multilayers Electrodeposited from Ethaline
Authors: Salgueira João F. S. , Sousa Natalia G. , De Lima-Neto Pedro , Casciano Paulo N. S. , Correia Adriana , Schwarzacher Walther
Published: February 2024

Many researchers have studied metal/metal multilayer films electrodeposited from a single electrolyte under potentiostatic or galvanostatic control. When the electrolyte contains a high concentration of a less noble metal and a low concentration of a more noble one it is possible to alternate between depositing the latter in pure form and an alloy whose composition is dominated by the less noble component through switching either the deposition potential or current density. Most work in this field has used aqueous electrolytes, but in some situations working with alternative solvents could offer advantages. Here we present results for Ni-Cu/Cu multilayers electrodeposited from an ethaline (1:2 choline chloride : ethylene glycol) electrolyte containing 0.06 M Cu and 0.6 M Ni. The deposition potential was alternated between -0.6 V vs. Ag/AgCl at which Cu was deposited and -1.1 V at which a Ni-Cu alloy was expected. Specular films consisting of multiple repeats with nominal thicknesses down to 10 nm Cu/ 10 nm Ni-Cu were obtained.
(Invited) Dealloyed Materials for Corrosion Protection
Authors: Erlebacher Jonah , Baris Jodie , Zhou Chengao , Hou Sonia , Wang Chao , Anber Elaf , Lech Sebastian , Taheri Mitra
Published: February 2024

Dealloying has become a wildly popular method to produce complex porous materials with controlled nanostructure. Many types of dealloying are now used, from traditional electrochemical dealloying in which an electrolyte is used for selective etching, to more recent innovations such as liquid metal dealloying where a molten metal is used as a "solvent" and dealloying is driven by enthalpic affinity for one component to dissolve into the molten bath. Historically, dealloying was first intensively studied in the context of corrosion. Dealloying was something to be avoided, not celebrated. Here we turn the question on its head - can we make dealloyed materials that are corrosion-resistant? Toward this end, we report our examinations of studying the corrosion response of two-phase NiTi/Cr films made on engineering alloys by a kind of liquid metal dealloying. These materials exhibit interesting responses associated with their complex two-phase nanostructure formed during the dealloying reaction.
Self-Detachment of Nanoporous Thin Films
Authors: Henkelmann Gideon , Weissmuller Jorg
Published: February 2024

Nanoporous metals consist of a network of interconnected ligaments with diameters tunable between 5 and 500 nm. The talk focusses on nanoporous metal thin films prepared by electrochemical dealloying of 300 nm thick Au25Ag75 films deposited on a pure Au base layer. This type of nanoporous gold film is the subject of many studies investigating the material as sensor, as catalyst, or as substrate for energy storage.

The massive Au base layer is intended as an adhesion promoter and to prevent the corrosion from attacking the substrate. Yet, contrary to expectation, we observed that the as-dealloyed nanoporous films developed a gap near the base layer, with extremely loose connection. Screening electron micrographs in earlier publications revealed that the deficit in connectivity is ubiquitous – even though it has not been broached. We could readily reproduce the feature in kinetic Monte Carlo simulations of dealloying, with no special assumptions on the processes near the base layer. The talk will describe these observations, and we argue that the evolution of the connectivity in nanoporous thin films is sensitive to gradients, in the direction of the film thickness, of the laterally averaged surface mean curvature. Specifically, surface diffusion driven by the energetically favorable planar substrate results in a net current from ligaments connected to the substrate towards the substrate, leading to degradation and eventual pinch-off of these ligaments. A similar phenomenon occurs at the outer surface, causing densification and retraction of the outermost ligaments.

Our findings suggest that this phenomenon may be relevant for all nanoscopic contact interfaces where surface diffusion is sufficiently fast. These results have significant implications for the design and implementation of nanoporous thin films in various applications, including sensor and actuator devices. Mitigation strategies will be discussed.

Reference:

G. Henkelmann, D. Waldow, M. Liu, L. Lührs, Y. Li and J. Weissmüller; Self-Detachment and Subsurface Densification of Dealloyed Nanoporous Thin Films. Nano Lett 22 (2022) 6787.

Figure 1
(Invited) Making Nanostructured Composites Via Inner-Pore Electrodeposition into Nanoporous Metals
Authors: El-Zoka Ayman A.
Published: February 2024

The selective removal of Ag from a solid solution of Ag-Au or Ag-Au-Pt yields a 3D bicontinuous, open-pore, nanoporous gold substrate (NPG), that is rich in the more noble metal(s)1 (Au and/or Pt). NPG has been successfully developed by the intelligent use of the conventionally-undesired dealloying corrosion. The excellent properties of NPG are attributed to the surface area-to-volume ratio, and high curvature of nanoligament surfaces2,3
. While a lot of recent research has been focusing on the structure/property relationships of NPG as a functional material in its own right4,5, the further use of NPG as a sophisticated template for fabricating complex nanostructured materials is worthy of attention.

Previous work on atom probe tomography characterization of NPG6,7 showed the successful inner-pore electrodeposition of a fully compact Cu support, thus, opening the door to implementing that newly developed method to the creation of finely tuned nanostructures, using NPG as a template. Fabrication of functional nanostructures pertaining to the interests of the catalysis and mechanics communities will be demonstrated through the electrodeposition of Cu and Co on NPG. Key aspects that enable this unexpected complete infiltration of NPG layer will be highlighted including, a characteristic "subpotential" curvature-driven electrodeposition regime8. Insights on the associated electrodeposition mechanisms are gained through the pairing of electrochemical methods and high-resolution characterization techniques. Furthermore, recent advances in structural and chemical modifications that increase the complexity and tunability of NPG-based nanocomposites will be discussed for the first time.

References

Newman, R. C. 2.05 - Dealloying. in Shreir’s Corrosion (eds. Cottis, B. et al.) 801–809 (Elsevier, 2010).

Zielasek, V. et al. Gold Catalysts: Nanoporous Gold Foams. Angewandte Chemie International Edition
45, 8241–8244 (2006).

Xue, Y., Markmann, J., Duan, H., Weissmüller, J. & Huber, P. Switchable imbibition in nanoporous gold. Nature Communications
5, (2014).

Wittstock, A., Wichmann, A., Biener, J. & Bäumer, M. Nanoporous gold: A new gold catalyst with tunable properties. Faraday Discuss (2011) doi:10.1039/c1fd00022e.

Li, X. et al. Nanoporous-Gold-Based Hybrid Cantilevered Actuator Dealloyed and Driven by A Modified Rotary Triboelectric Nanogenerator. Sci Rep (2016) doi:10.1038/srep24092.

El-Zoka, A. A., Langelier, B., Botton, G. A. & Newman, R. C. Enhanced analysis of nanoporous gold by atom probe tomography. Mater Charact
128, (2017).

El-Zoka, A. A., Langelier, B., Korinek, A., Botton, G. A. & Newman, R. C. Nanoscale mechanism of the stabilization of nanoporous gold by alloyed platinum. Nanoscale
10, (2018).

Lee, L., He, D., Carcea, A. G. & Newman, R. C. Exploring the reactivity and nanoscale morphology of de-alloyed layers. Corros Sci
49, 72–80 (2007).
Modification of Anodic TiO2 Nanotubes with Au
Authors: Kowalski Damian , Henkiel Patrycja , Sepúlveda Lina , Vincent Mewin
Published: February 2024

For many years gold has been considered as catalytically inactive until Haruta and Hutchings demonstrated its catalytic behaviour in low-temperature CO oxidation.1 The bulk gold is generally considered as a poor catalyst and becomes surprisingly active when its size is reduced to nanoscale dimension. The recently emerging field of plasmonics require precise control of gold structure at the nanometer and subnanometer scales particularly if combined with secondary materials such as titania. Herein, we aim to control the structure of Au on TiO2 nanotubes by means of anodizing of TiAu alloys and two step process of anodizing of titanium and subsequent electrodeposition of gold in nanotubes.2,3 Figure 1a shows comparison of Ti and TiAu alloy anodized in mono-ethylene-glycol electrolyte containing 0.1 mol.dm-3 ammonium fluoride and 1 mol.dm-3 of water.2 The accumulation of gold at cell boundaries and resulting modification of TiO2 nanotube outer-shell can be clearly recognized from backscattered SEM images. Figure 1b shows the nanostructure formed by gold electrodeposition in between TiO2 nanotubes synthesised in di-ethylene-glycol electrolyte containing 2 wt.% HF and 2 wt.% of H2O.3 The details of nanostructures growth and possible applications will be discussed.

References:

(1) Haruta, M., Nature, 437, 1098-1099 (2005).

(2) Sepúlveda, M., Castaño, J.G., Echeverría, F., Aouki, Y. Kowalski, D., Habazaki, H., Electrochemistry Communications, 120, 106847 (2020).

(3) Kowalska E., Juodkazis S., Henkiel P., Kowalski D., ACS Applied Nano Mat., 5 7696-(2022).

Figure 1 a) SEM images of Ti and Ti-Au alloy anodized at 60V for 50 s in mono-ethylene-glycol electrolyte containing 0.1 mol.dm-3 ammonium fluoride and 1 mol.dm-3 of water; b) top image shows backscattering electron SEM image of Au electrodeposited in between nanotubes, the bottom image shows TEM of FIB lamella and corresponding EDS mapping (red: Ti, yellow: Au) for TiO2/Au composite, c) FDTD modeling of the light absorption and scattering cross-sectional spectra for nanostructures.

Figure 1
Weakly Nonlinear Analysis of Flow-Driven Porous Anodic Oxide
Authors: Wankhede Sajal , Pillai Dipin S.
Published: February 2024

Porous anodic oxide (PAO) films are formed by the electrochemical oxidation of metals such as titanium, aluminum, and other metals in acidic solutions. The optimal selection of parameters leads to the formation of submicron-sized pores arranged in a parallel hexagonal array within these films. Porous anodic oxide has enormous industrial applications in the development of functional nanodevices. The present study builds upon the flow-driven porous anodic oxide model proposed by Mishra and Hebert. They have shown through a linear stability analysis of the model that the inter-pore distance in PAO is successfully determined by the competition between stabilizing oxide formation and destabilizing viscous flow. In this work, we investigate the weakly nonlinear analysis of the model to determine the nature of instability arising in flow-driven porous anodic films beyond the stability threshold. For formation of well- developed pores, the nature of instability must be subcritical. However, the results of weakly nonlinear analysis show that the solutions resulting from neutral stability exhibit a supercritical nature for the practical range of anodizing control parameters as shown in Figure 1. Thus, in order to make accurate nonlinear predictions about the formation of pores, it is imperative to incorporate additional physics into the viscous flow model. We also determine the Hadamard stability criteria by tracking the neutral wavenumber to ascertain the regions of well- posedness of the viscous flow model.

Figure 1
(Invited) Tailor-Made Hierarchical Nested-Network Nanoporous Metals By Dealloying
Authors: Shi Shan
Published: February 2024

Structural hierarchy is known to optimize functional and mechanical behaviors in deliberately designed structures and natural materials. The benefits of hierarchy implementing the high strength and the high surface-to-volume of nanoscale objects into hierarchical structures would lead to even more interesting mechanical characteristics and more opportunities for interface- or surface-controlled functional applications. This talk focuses on nested network random nanomaterials "hierarchical nanoporous gold" made by two-stage self-organization dealloying processes, which processes allow for large samples contained over trillions of struts to be synthesized. Both the strut size and porosity at each hierarchy level are tuned independently. The strut size can be controlled from 10 nm to 300 nm, and the porosity from 80% to 90%. Compression tests on these hierarchical nanoporous gold materials demonstrated that the structural hierarchy brings enhanced mechanics for truly nanoscale network materials. The experiments are well supported by our proposed scaling laws for the stiffness and strength for nested network with different numbers of hierarchy levels [1].

[1] S. Shi, Y. Li, B.-N. Ngo-Dinh, J. Markmann and J. Weissmüller, Scaling behavior of stiffness and strength of hierarchical network nanomaterials, Science 371 (6533), 2021.
Electrodeposition of 3D Au1-XAgx Nanowire Networks – Influence of Ag on the Electrochemical Properties
Authors: Li Mohan , Schubert Ina , Ulrich Nils , Sigle Wilfried , Moreno Fernandez Harol , Trautmann Christina , Toimil Molares Maria Eugenia
Published: February 2024

We present the synthesis of free-standing Au1-xAgx alloy nanowire networks with controlled geometry and atomic composition, by ion track nanotechnology and electrodeposition, and their electrochemical characterization.

Polycarbonate polymer templates with interconnected nanochannels are fabricated by sequential irradiation from four directions with 1-2 GeV Au ions at the UNILAC accelerator of GSI, followed by selective chemical etching of the ion tracks. [1] Au1-xAgx alloy nanowires are subsequently synthesized by potentiostatic electrodeposition inside the channels. Nanowire growth rate and atomic composition are tuned by varying the deposition potential and the electrolyte composition. The technique provides precise control of the nanowire size, interconnectivity, and composition. [2,3,4] By dissolving the polymer template, free standing nanowire networks are obtained showing good mechanical stability. Geometry, crystallinity, and composition of the alloy Au1-xAgx nanowires were analysed by TEM, EDX, and XPS. The results demonstrate that the Ag molar fraction can be precisely adjusted between 10% and 90%.

The electrochemically active surface area was determined by measuring the double layer capacitance of the nanowire network surface, and is in good agreement with the calculated theoretical surface area. The 3D network exhibit surface areas up to 200 times larger than their planar counterpart, which makes them highly interesting for catalytic processes. Their electrochemical activity in alkaline solution is investigated by cyclic voltammetry in 0.1 M KOH electrolyte, and will be discussed in this presentation.

[1] M.E. Toimil-Molares, Beilstein Journal of Nanotechnology, 3.1, 860-883 (2012).

[2] M. Rauber, I. Alber, S. Müller et al. Nano Letters, 11.6, 2304-2310 (2011).

[3] L. Burr, I. Schubert, W. Sigle et al. The Journal of Physical Chemistry C, 119.36, 20949-20956 (2015).

[4] M. Li, N. Ulrich, I. Schubert et al. RSC Advances, 13, 4721-4728 (2023).
3-D Nanostructure Palladium Synthesis By Electrochemical Deposition for Hydrogen Sensor with Switching Resistance Characteristic in Normal Temperature and Pressure
Authors: Hwang Inseong , Park Subeen , Seo Jinmyeong , Song Yunha , Yoon Sanghwa , Yoo Bongyoung
Published: February 2024

In the hydrogen industry, it is crucial to detect hydrogen leaks and monitor its concentration due to its highly explosive, flammable, and diffusive properties in the concentration range of 4%-75%. Until now, hydrogen sensors have been focused on oxide materials at high temperature and pressure conditions such as semiconductor and steel processes. However, in the future of the hydrogen industry, it is important to sense hydrogen at normal temperature and pressure (NTP). To develop hydrogen sensors with fast response time and high sensitivity specifically designed for NTP conditions, various material properties and structural aspects such as film, nanostructure, and multilayer are being experimentally explored.

Metal resistance hydrogen sensors utilize changes in resistance due to hydrogen adsorption and absorption. Compared to other sensors such as catalytic and thermal conductivity sensors, metal resistance hydrogen sensors have advantages such as excellent sensitivity, response time, and selectivity. Palladium metal exhibits superior characteristics with regard to hydrogen compared to other metals, due to its low activation energy for hydrogen molecule dissociation reaction and high reactivity in absorbing hydrogen at NTP.[1] Also, palladium with 3-D nanostructures exhibits a switching resistance characteristic, where the resistance initially decreases rapidly and then increases because of hydrogen and palladium reaction.[2] This depends on the hydrogen concentration and exposure time, which is due to a phenomenon where the combined effects of characteristics such as hydrogen interstitial, phase transition, and volume expansion lead to different responses of hydrogen and palladium.

In this study, we focused on the resistance switching characteristic of palladium, specifically its response to changes in hydrogen concentration and exposure time. We used this characteristic to experiment with both the material and structural properties of palladium nanostructures. We varied impurities and additives in the palladium electrodeposition solution to control the material properties, and varied parameters such as concentration, pH, and voltage using electrochemical methods for structural properties. Structural and material properties were analyzed using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and X-ray Photoelectron Spectroscopy (XPS). Sensing characteristics were then analyzed using a hand-made sensor platform with a Source Meter.

[Reference]

[1] Dekura, S., Kobayashi, H., Kusada, K., & Kitagawa, H. (2019). Hydrogen in Palladium and Storage Properties of Related Nanomaterials: Size, Shape, Alloying, and Metal‐Organic Framework Coating Effects. ChemPhysChem, 20(10), 1158-1176.

[2] Cho, S. Y., Ahn, H., Park, K., Choi, J., Kang, H., & Jung, H. T. (2018). Ultrasmall grained Pd nanopattern H2 sensor. ACS sensors, 3(9), 1876-1883.
(Invited) Magnetic Field Assisted Electrodeposition of Topographically and Chemically Structured Copper-Nickel Deposits
Authors: Tschulik Kristina , Gerwin Maximilian , Jlailati Zaher
Published: February 2024

Electrodeposition under the influence of magnetic field has sparked the interest of researchers for decades. The beneficial effects of homogenous magnetic fields on electrodeposition enable increased deposition rates as well as smoother deposits.[1] These effects have been intensively studied and attributed to magnetohydrodynamic forces. Conversely, several questions remain unanswered with respect to the beneficial influence of heterogeneous magnetic fields.[2] There, local convection allows structuring of deposit morphologies; however, it has not yet been reported if magnetic gradients can be used to induce local compositional changes.[3] Here, we investigate the opportunity to induce both, topographic and chemical structuring of electrodeposits by magnetic gradients.

For this purpose, potentiostatic deposition of CuNi films is carried out on an Au coated glass slide using a sulphate-based aqueous electrolyte. An iron wire template is magnetised by a permanent magnet and placed below the working electrode to apply well defined, high magnetic gradients during electrodeposition. The obtained Cu-Ni deposits are analysed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The results of these measurements reveal that the deposited film topography follows the distribution of superimposed magnet field gradients and that a local compositional change of the deposits is possible. Thus, our results open up a new path to control the local morphology of complex deposits structures and other properties of films by magnetic gradient assisted electrodeposition.

References

(1) Uhlemann, M.; Tschulik, K.; Gebert, A.; Mutschke, G.; Fröhlich, J.; Bund, A.; Yang, X.;

Eckert, K. Eur. Phys. J. Spec. Top. 2013, 220, 287–302.

(2) Mutschke, G.; Tschulik, K.; Weier, T.; Uhlemann, M.; Bund, A.; Fröhlich, J.

Electrochimica Acta 2010, 55, 9060–9066.

(3) Karnbach, F.; Uhlemann, M.; Gebert, A.; Eckert, J.; Tschulik, K. Electrochimica Acta

2014, 123, 477–484
Electropolymerization of a Conjugated Polymer on Top of a Different Conjugated Polymer for Yarn Actuators
Authors: Martinez Jose G. , Mehraeen Shayan , Jager Edwin
Published: February 2024

Electropolymerization of conjugated polymers is usually performed on highly conductive metallic electrodes. However, for applications such as textile actuators this is not possible. There, the electropolymerization is performed on a different, previously deposited conjugated polymer. This resulted on some new electrochemical phenomena not present when the electropolymerization is done on a metallic substrate. Processes as the oxidation and overoxidation of the underlying conjugated polymer need to be taken into account. In this work we have investigated the best conditions for electropolymerization of polypyrrole on top of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) coated textile yarns, when the electropolymerization was performed by either cyclic voltammetry, chronoamperometry or chronopotentiometry in order to achieve the best electroactive and actuating conjugated polymer.
Tailoring Substrate Topography to Enhance Wicking Performance of Electrodeposited Cu Porous Films
Authors: Liu En-Chia , Yu Jui-Cheng , Chiang Chao-Yang , Liao Chien-Neng
Published: February 2024

Porous metallic films have received emerging interests in the fields of catalysts, fuel cells, lithium batteries, and phase-change heat transfer devices. Substrate topography is known to have a strong impact on adhesion and morphology of porous coating layers prepared by electrodeposition. In this study, we have tailored the topography of a Cu substrate by wet etching in a sodium persulfate/sulfuric acid (SPS) solution prior to electrodeposition of porous Cu films. An analytic approach is proposed to quantitatively analyze nucleation and growth of dendritic Cu deposits on the SPS-treated Cu substrates. Such a dendritic porous Cu film can serve as a capillary wick to complete recirculation of condensed liquid in the phase-change heat transfer devices. The maximum heat transfer rate of a heat pipe or vapor chamber indeed is proportional to the capillary performance (K/Reff
) of the wick structure, where K and Reff
stand for liquid permeability and effective pore radius of the wick, respectively. A large K/Reff
value of 0.975 µm has been attained for the electrodeposited dendritic Cu film on a Cu substrate with an optimal SPS etching treatment. The influence of dendritic deposits on the wicking performance of the electrodeposited Cu film is investigated.

Figure 1
Cost-Effective Milled Silicon and Exfoliated Graphene Anode for High-Performance Li-Ion Batteries
Authors: Aziz Mohammad Abdul , Joo Yong Lak , Gao Ziang
Published: February 2024

Lithium-ion batteries play a significant role in modern electronics and electric vehicles. However, current lithium-ion battery chemistries are unable to satisfy the increasingly heightened expectations regarding energy demand and reliability. To boost the overall energy density while ensuring the safety of Li batteries, researchers have focused on developing the battery materials [1]. Silicon has an ultrahigh theoretical capacity and has been regarded as the best choice for next-generation lithium-ion battery anodes, but it also suffers from dramatic expansion during cycling [2]. Hence mitigating volume expansion is one of the main challenges towards developing a successful Si based anodes. Herein, a facile air-controlled electrospray method to directly deposit silicon/graphene (Si/Gr) onto current collectors was described. This method is inspired by an electrospinning process and possesses all the advantages that electrospinning has such as low cost, easy scaling up, and simultaneous solvent evaporation during the spraying process. Cost-effective silicon/graphene (Si/Gr) composite electrodes have been investigated for the multiple benefits of Gr in providing mechanical integrity to buffer the silicon volume expansion while maintaining electronic contact with Si to provide a Li-ion transport pathway and to form a uniform solid electrolyte interface (SEI) layer. Our results revealed a superior battery performance including a capacity of 1000 mAh/g at 2C rates and minor capacity loss during long cycling. The details of synthesis, characterization, and lithium-ion battery results of the hybrid anodes will be presented.

References

[1] Li et al., Adv. Energy Mater., 2021, 11, 2003239.

[2] Guo et al., Adv. Funct. Mater., 2021, 31, 2102546.
Revealing Aqueous-Processing Ni-Rich Cathode Cycling Performance in Term of Cathode Electrolyte Layer Formation and Phase Transition
Authors: Chen Heyin , Hahlin Maria , Brant William Robert
Published: February 2024

Traditionally, Ni-rich cathodes for lithium ion batteries are produced by utilizing N-methyl-2-pyrrolidone (NMP) based casting. However, in order to prevent using the harmful solvent NMP, aqueous-processing method becomes one of the options.1 In this study, water-based electrodes have been produced to compare with the NMP-based electrodes. In addition to that, phosphoric acid addition was involved to modify the water-based electrode surface to improve the capacity retention.2 We used X-ray adsorption spectroscopy (XAS) to observe the existence of NiO phase in the aqueous processed electrodes due to Li/Ni disorder. The Galvanostatic cycling results shows that aqueous processed electrodes provide worse capacity retention compared with the NMP processed electrodes because of higher electron transfer resistance, which is caused by the cathode electrolyte layer (CEI) layer formation. Soft X-ray photoelectron spectroscopy (PES) results show that comparing to NMP-based electrodes, water-based electrodes contains more decomposition species from electrolyte in CEI layer after first battery cycle. From Operando X-ray diffraction, we observed the phase transition differences between these three types of electrodes. In this study we aim to answer if and/or how the additive phosphoric acid participates in the electrolyte degradation during battery cycling. A deeper understanding of the roles of acid can provide a new path to develop aqueous-processing electrodes method.

Wu, F.; Kuenzel, M.; Diemant, T.; Mullaliu, A.; Fang, S.; Kim, J. K.; Kim, H. W.; Kim, G. T.; Passerini, S., Enabling High‐Stability of Aqueous‐Processed Nickel‐Rich Positive Electrodes in Lithium Metal Batteries. Small
2022, 2203874.

Bichon, M.; Sotta, D.; De Vito, E.; Porcher, W.; Lestriez, B., Performance and ageing behavior of water-processed LiNi0.5Mn0.3Co0.2O2/Graphite lithium-ion cells. Journal of Power Sources
2021,
483.
Valorization of Waste Plastics into Nanostructured Materials for LI-ION Storage Application
Authors: Kamali Ali Reza
Published: February 2024

Every year, several million tons of plastics are wasted, resulting in significant environmental pollution. Polyethylene terephthalate (PET) is one of the most commonly used plastics, with approximately 400 billion drink bottles produced annually. The widespread availability and environmental concerns associated with the non-natural degradability of PET waste necessitate the development of clean, efficient, and low-cost recycling methods or valorization into high-value materials. In this presentation, the molten salt conversion of waste PET into carbonaceous nanostructures is discussed as a facile, scalable, and fast method for valorizing PET waste. For instance, this molten salt process can result in the preparation of terephthalic acid embedded with tin dioxide nanocrystals. The resulting nanocomposite material shows interesting performance as anode of high-performance lithium-ion batteries. The structural, morphological and electrochemical performance of the terephthalic acid- tin dioxide are discussed in this presentation.