bluuebunny/crossref_metadata_2025_split huggingface dataset:
(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.
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.
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
(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.