bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Coordination Controlled Electrodeposition of Metal Nanostructures
Authors: Buck Manfred 
Published: July 2022

It is the combination of features related to surface chemistry, charge transfer, and interfacial energies which makes self-assembled monolayers (SAMs) attractive templates for electrodeposition. However, as in other additive processes such as atomic layer or electroless deposition where SAMs are harnessed for area selective deposition, one is faced with substantial challenges when advancing to the ultrasmall scale. Based on defects in a chemically inert SAM, the established scheme of SAM controlled electrodeposition offers a very convenient way to generate patterns but is only applicable down to the length scale of a few tens of nanometers. The statistical nature of defects does not provide the level of control over the deposition process required to move further towards the bottom range of the nanoscale.
For this reason we have been exploring a deposition scheme which builts on features intrinsic to the SAM molecules and, therefore, promises a more precise control over decisive steps in the deposition process.1 The essential point is the paradigm shift from a mushroom like deposition at defects to a deposition via coordinated metal ions using a suitably functionalized SAM. As illustrated in the cartoon, nuclei generated by discharging a two-dimensional layer of ions act as seeds for the deposition from the bulk electrolyte. Yielding layers on top of the SAM, this coordination controlled deposition not only enables a further reduction in lateral dimensions of patterns to below 20 nm but also shifts the percolation threshold, yielding continuous layers at a thickness of about 2 nm. In relation to this the average roughness of below 0.4 nm is substantial and further improvement is needed. Key to this and a further reduction in dimensions is the understanding of the processes determining the seed formation and how these can be controlled by the design of the SAM. Informed by calculations which show a strong interaction between metal atoms and the terminating aromatic unit of the SAM,2 studies of binary layers consisting of coordinating and non-coordinating molecules have been performed. The average size and size distribution of the particles depend on the composition and mixing ratio, and a significant reduction in size to about 2 nm can be achieved, suggested that the diffusion length is reduced and nucleation is promoted in mixed SAMs. The results show that SAMs provide a range of design opportunities through which coordination controlled electrodeposition can be further developed towards ultrasmall structures.
1. Z. She, Z. Yao, H. Ménard, S. Tobish, D. Lahaye, N. R. Champness, M. Buck,
Coordination controlled electrodeposition and patterning of layers of palladium/copper nanoparticles on top of a self-assembled monolayer,
Nanoscale 11, 13773-13782 (2019).
2. Z. Yao, M. Buck, M. Bühl,
A Density Functional Theory Study of Pd Aggregation on a Pyridine-Terminated Self-Assembled Monolayer,
Chem. Eur. J. 26, 10555-10563 (2020).

Figure 1
(Invited) In-Situ Observation of Electrodeposition Processes By High Speed Scanning Probe Microscope
Authors: Matsushima Hisayoshi 
Published: July 2022

Electrodeposition is important technology for developing the novel functional materials such as MEMS. In nanotechnology term, the metal deposition is one of the hot topics since it can control the surface structure precisely and easily.
Generally, in metal electrodeposition, an adatom deposited on the electrode diffuses and reaches a step or kink before forming a crystal. In the process, the solvents and additives adsorbed on the surface are often incorporated into the deposits. Since they works as an impurity in the film, they induce the crystal defects and surface defects, which may cause the performance degradation of the produces. Because each processes occur at high speeds and on the atomic scale, the deposition mechanism is difficult to understand.
The methods for observing the nucleation have been developed in various ways. With the invention of the scanning probe microscope (SPM) in the 1980’s, we could directly observe the nanostructure. It has been applied to the electrodeposition in aqueous solution. However, since SPM usually takes some time to observe the surface, it is very difficult to catch the dynamic process such as the nucleation and growth of the deposits. Therefore, I believe that the high-speed SPM is the promising solution of both temporal and special problems.
There are two types of SPM: scanning tunneling microscope (STM) and atomic force microscope (AFM). In the former type, there is a video rate STM (Video STM) that can capture up to 30 frames per second. Furthermore, the spatial resolution can reach the atomic scale. For example, the Bi kink growth along the step is reported and Pb surface diffusion on the Cu surface is clarified [1-3]. However, since the tunneling current flows continuously between the probe and the substrate during the measurement, it is necessary to sufficiently consider the effects on electrochemical reactions.
Although the resolution of the high-speed scanning AFM (HS-AFM) is inferior to that of the STM, the influence of the probe can be less. Therefore, in addition to the nucleation phenomenon during Cu electrodeposition (Fig. 1-A) [4], we have observed the weak adsorption of PEG polymer that is known as the major additives during the electrodeposition (Fig.1-B). By taking the advantage of the low contact pressure of the probe, the transient behavior of nucleation and growth of electrolytic nanobubbles can be observed.
In this presentation, the dynamic variations of the electrolytic nucleation & growth by using a high-speed SPM will be presented.

References

H. Matsushima et al., Faraday Discuss., 193 (2016) 171.

A. Taranovskyy et al., Phys. Chem. Chem. Phys., 14 (2012) 10579.

S. Guezo et al., J. Phys. Chem. C, 115 (2011) 19336.

T. Yoshioka et al., Electrochim. Acta, 302 (2019) 422.

Figure 1
Influence of 1,1-Dimethylpropargylamine on Nickel Electroplating
Authors: Moazezi Alireza , Schmidt Udo , Ispas Adriana , Bund Andreas 
Published: July 2022

Nickel electroplating is widely used for decorative thin films, for better abrasion resistance and increased corrosion protection. The properties of the nickel deposit, such as its structure and morphology, can be varied by adding different organic additives to the nickel electrolyte. For example, additives such as coumarin and saccharin are used in nickel plating to generate a nickel film with uniform thickness on rough substrates.
Levelling is referred to as a process of progressive reduction of surface roughness during electrodeposition. In this case, scratches or non-uniform structures on the cathode represent the initial roughness, and the result of cathodic deposition is a smooth levelled layer with reduced roughness. In this type of levelling, more metal is deposited in the grooves than on the elevated surface features. This is due to the fact that metal deposition is less inhibited in the recessed features. True levelling requires the presence of appropriate levelling agents and brighteners. A wide variety of organic compounds are used as brighteners e.g. olefinic, acetylenic and sulphur and nitrogen containing compounds.
The singular and synergistic effect of the following additives on Ni electroplating was investigated and discussed in this work, such as the 1,1-dimethylpropargylamine (MPA:5 to 20 mg/L), sulfopropylated butynediol (HBOPS: 7.5 or 75 mg/L), 1-(3-sulfopropyl)-pyridinium betaine (PPS: 1.6, 3.2 or 150 mg/L), saccharin (1.5 g/L) and sodium allyl sulfonate (ALS: 1.5 g/L).
Reflectance and colour measurements showed that the samples coated from nickel electrolyte containing 5mg/L MPA and 7.5 mg/L HBOPS exhibited better uniformity, gloss and good throwing power in the low current density regime when compared to the electrolytes containing other additives or without MPA. Cross section analyses of the deposits indicate that the MPA is not only acting as a strong brighter, but it also helps in levelling (Fig. 1). XRD measurements indicated the effect of the different additives on the structure of the nickel deposits.
Fig. 1. Cross section of a sample deposited for 72 minutes at 2 A/dm² and 50 °C from a Ni electrolyte containing 240 g/L NiSO4 x 7 H2O, 40 g/L NiCl2 x 6 H2O, 30 g/L H3BO3, 0.5 g/L SDS, 1.5 g/L saccharin, 1.5 g/L ALS, 1.6 mg/L PPS, 7.5 mg/L HPOPS und 5 mg/L MPA

Figure 1
(Invited) Dynamic Plating/Stripping Behavior of Zn Anode in an Operating Aqueous Zn-Ion Battery
Authors: Liu Yijin 
Published: July 2022

To circumvent the fossil resource depletion and to reduce the carbon emission, electrochemical energy storage technique undergoes blooming developments over the past few decades. A promising candidate for electrochemical energy storage is the rechargeable Zn aqueous battery, which has the merits of rich Zn abundance, low cost, high safety, and environmental friendliness. Despite of enormous research and engineering investments, the practical implementation and deployment of Zn aqueous battery are still hindered by challenges concerning several different aspects of the electrochemical reaction involving Zn-ions. One of the main obstacles is that the Zn anode suffers from a low Coulombic efficiency, and the underlying mechanism is related with the non-ideal reversibility of the Zn plating/stripping process. The behavior of Zn plating and stripping is sophisticated and can be modulated by several co-existing and intertwined factors, including the electrode configurations, the charging/discharging protocols, and the composition of the electrolyte.
For example, it has been demonstrated that the anode morphology can affect the dendrite growth. By fabricating Zn anode with a 3D sponge structure, the Ni-Zn cells could exhibit an improved cycle performance and a suppressed dendrite formation. Plating with high current density could exacerbate the electrochemical polarization and tends to form Zn dendrites. As a mitigation, the Zn dendrites can be dissolved by applying a small current during the stripping process. In addition, surface chemistry on anode plays a critical role in the Zn plating/stripping process. The reactions involving the solid-liquid interphase are often complicated and may vary depending on the electrolyte used. A holistic investigation of the structural, dynamic, and chemical features in Zn-ion batteries under operating conditions is key to the development of high-performance Zn-ion battery.
In this talk, I will present our recent study using in-situ X-ray tomography and operando X-ray radiography to investigate the Zn plating/stripping behaviors in an in-house developed aqueous zinc-ion battery cell. We electrochemically plate Zn on a three-dimensional Cu foam and reveal how the electrode configuration and the local morphology collectively regulate the Zn plating behavior. Through advanced quantification and analysis of the tomographic data, we uncover that the Zn deposition in ZnSO4 electrolyte exhibits a substrate-curvature dependence. We further investigate how the current density would modulate the Zn plating using operando X-ray radiography. I will also briefly discuss the possibility of utilizing a novel tri-contrast x-ray imaging method to image dendric structures with better sensitivity and contrast.
(Digital Presentation) On Demand Electrochemical Peroxide Generation for Disinfection
Authors: Vijapur Santosh Hanamant , Hall Timothy , Taylor E. Jennings , Wang Dan , More Santosh R , Liu Danny , Snyder Stephen , Skinn Brian 
Published: July 2022

Novel technologies with limited earth support are required to enable habitation in microgravity spacecraft habitats such as International Space Station (ISS). Disinfection needs is an area of particular need, which is currently accomplished through the use of pre-packaged, disposable, wetted disinfection wipes. These items represent an appreciable carry-along mass and disposal/replacement burden requiring ground support. Therefore, a system is desired that could utilize onboard utilities to create disinfecting solutions to eliminate storage/disposable problems of the wetted wipes and further reduce the astronaut’s dependence on earth-based supplies.
Faraday Technology Inc. is addressing this challenge by demonstrating an in-situ approach, which utilizes on-board supplies of air and water for on demand electrochemical generation of hydrogen peroxide. Hydrogen peroxide is well-established disinfectant with non-toxic decomposition products (viz., O2 and H2O), that is safe enough for human contact to be sold commercially as a 1-5 w/w% solution, which makes it an ideal disinfecting solution for closed space environments. Faraday has continued to improve the TRL by scaling the electrochemical peroxide generation system from a sub-scale to alpha-scale process in order to deliver 1 L per day of ~2 w/w% hydrogen peroxide for disinfectant applications from DI water feed-stream with air as a feed source
[1],[2],[3],[4]
. These electrolytes were then sent to NASA for microbial control property characterization. Specifically, this talk will discuss the results of these advancements.

Acknowledgements: Financial support of NASA Contracts NNX16CA43P, NNX17CJ12C, and 80NSSC20C0070 is acknowledged.

References:

[1] Vijapur, Santosh H., et al. "Electrochemical peroxide generation." ECS Transactions 77.11 (2017): 947.

[2] Vijapur, Santosh, et al. "In-Situ Resource Utilization for Electrochemical Generation of Hydrogen Peroxide for Disinfection." 49th International Conference on Environmental Systems, 2019.

[3] Nelson, George J., et al. "Electrochemistry for Space Life Support." The Electrochemical Society
Interface 29.1 (2020): 47.

[4] Vijapur, Santosh, et al. "In-Situ Resource Utilization for Electrochemical Generation of Hydrogen Peroxide for Disinfection." 50th International Conference on Environmental Systems, 2021.
An Electro-Reductive Removal of Gaseous Toluene By a Copper-Nickel Complex Mediator at Gas-to-Solid Interface
Authors: Kim Daekeun , Choi Youngyu , Govindan Muthuraman 
Published: July 2022

Electrochemical technique is one of the most promising methods for the removal of volatile organic compounds such as toluene. However, the conventional gas electrolysis method has mass transfer limitation, and the homogeneous catalysts are often irrecoverable after the reaction is completed, which leads to inefficient, less environmental-friendly, and uneconomical performance. This study proposes a gas-to-solid electrolysis system employing an electrode coated with heterogenous catalyst as the electron transfer mediator. A CuNi(CN)4 complex was prepared according to a published method and drop-coated on a commercial copper mesh electrode with 5% Nafion solution. The CuNi(CN)4 coated copper electrode was further covered by 10 M of NaOH solution by drop-coating to increase the pH, which in turn widens the potential window. The prepared CuNi(CN)4 electrode was characterized by XRD and SEM-EDS analyses. The XRD and SEM-EDS analyses evidenced the CuNi(CN)4 presence with structural and composition details. Characteristics of electrodes and mediators were also confirmed through various analysis methods. Additionally, an electrochemical confirmation of CuNi(CN)4 presence by its redox behavior was inferred by gas-phase cyclic voltammetry. After confirmation of mediator presence, electrode mounted in a Nafion membrane divided electrolytic cell at the cathodic half-cell for the gas phase reductive electrolysis. A PVA gel was inserted in-between the Nafion membrane and the cathode to serve as a solid electrolyte to facilitate the electron transfer process. The electrochemical reduction of gas-phase toluene was carried out using a continuous flow model and chronoamperometry method. Different experimental parameters such as feed gas flow rates and concentrations were investigated on toluene removal. GC-MS analyses were applied to measure toluene concentration and intermediate compounds identification. A possible reaction mechanism will be discussed in detail at the conference.
Acknowledgment
This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education(NRF-2021R1I1A1A01049901) and also from the Grants No. NRF-2020R1A6A1A03042742
(Invited) Advancements in Vertical GaN p-n Junction Structures Via p-Type Ion Implantation
Authors: Goorsky Mark S. , Liao Michael Evan , Huynh Kenny , Wang Yekan , Anderson Travis J. , Tweedie James , Allerman Andrew A. 
Published: July 2022

Vertical GaN power devices have emerged to become promising candidates for next-generation high power applications due to superior material properties such as high breakdown voltage, low on-resistance, and high mobility compared to devices based on Si and SiC. GaN-based p-n junction switching devices enable higher voltage power with significantly higher efficiencies with added advantages of reduced size and weight systems. A technological limitation of GaN, however, has been the inability to achieve high p-type doping in a planar, vertical device. Here, we will focus on recent developments to achieve high p-type efficiency though ion implantation, novel high temperature annealing schemes, and the importance of defects and morphology in native substrates and epitaxial layers
GaN epitaxial layers for subsequent p-type ion implantation can be grown on sapphire substrates but vertical devices are optimal when using GaN homoepitaxial structures. Unlike most other semiconductor substrates, GaN substrates are not grown from the melt. Hydride vapor phase epitaxy or ammonothermal growth are predominantly used to produce substrates and these substrates will experience higher temperatures during subsequent epitaxy and ion implant activation annealing than occurs during substrate formation. In both types of substrates, the threading dislocation distribution can vary by orders of magnitude – these variations correlate well with leakage currents in vertical devices.
The activation of the implanted p-type dopants requires high temperature annealing. For most semiconductors, an annealing temperature of ~ 2/3 the melting point leads to a high activation fraction (> 95%) of the implanted species. The implantation process introduces large concentrations of native defects as well as the p-type implant (typically Mg), so it is necessary to remove the defects and for the dopants to locate on substitutional sites (Ga sites for Mg). We demonstrate how the formation of inverted domain defects at temperatures below 1400 °C correlate with Mg-compound formation, whereas annealing temperatures 1400 °C and above do not lead to the formation of such compounds but rather high Mg activation efficiencies.
These recent developments, partly through the ARPA-E PNDIODES program as well as international efforts, have brought understanding of the key processing steps and substrate requirements to achieve high activation efficiency p-type doping for planar, vertical device structures in a scalable framework.
(Invited) Materials Integration, Durability, and Perspectives in Anion Exchange Membrane-Based Low Temperature Electrolysis
Authors: Alia Shaun M , Intikhab Saad , Ha Mai-Anh , Ghoshal Shraboni 
Published: July 2022

As an energy carrier, hydrogen has unique advantages due to its high energy density, ability for long-term storage, and the ability to convert between chemical bonds and electricity. [1] Although hydrogen currently has a small role in energy pathways, decreasing electricity prices can allow for a significant growth opportunity. Compared to alkaline electrolysis, anion exchange membrane (AEM) systems utilize zero-gap membrane electrode assemblies that improve performance and potentially enable hydrogen compression with back pressure. Compared to proton exchange membrane (PEM) systems, the high pH of AEMs allows for non-platinum group metal (non-PGM) catalysts and component coatings (transport layers, separators) that can reduce system cost and improve long-term durability.
This presentation includes on an overview of NREL efforts in AEM electrolysis, and focuses on operation choices, materials integration, and catalysis. In recent years, membrane advancements have enabled higher AEM performance, particularly in supporting electrolytes. [2] Testing has included supported and unsupported (water) feeds, and operational strategies largely depend on the intended market. Efforts have been made to investigate the role supporting electrolytes play in improving AEM performance and assess the viability of AEM as a PEM replacement through water-only feeds and dry-cathode operation. [3,4]
Materials integration focuses on strategies for incorporating catalysts and ionomers that have improved water performance and allowed for short-term durability testing. [3] These efforts include coating approaches and processing conditions to rearrange catalyst layers, and detail the complications of developing protocol recommendations with component changes. In catalysis, fundamental studies have improved an understanding of materials requirements in the oxygen and hydrogen evolution reactions, and the impact of ionomer interactions on reactivity. Ab-initio simulations have provided feedback into low- and non-PGM catalyst development studies that improve device-level kinetics. Perspectives in AEM electrolysis will be discussed, and include ongoing needs for component development and durability testing, to separate and accelerate relevant degradation mechanisms.
References
[1] B. Pivovar, N. Rustagi, S. Satyapal, The Electrochemical Society Interface
2018, 27, 47.
[2] G. Bender, H. Dinh, HydroGEN: Low-Temperature Electrolysis (LTE) and LTE/Hybrid Supernode, https://www.hydrogen.energy.gov/pdfs/review20/p148a_bender_2020_o.pdf
2020.
[3] S. M. Alia, HydroGEN: Low Temperature Electrolysis, https://www.hydrogen.energy.gov/pdfs/review21/p148a_alia_2021_p.pdf
2021.
[4] S. Ghoshal, B. S. Pivovar, S. M. Alia, J. Power Sources
2021, 488, 229433.