bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Selectivity of CO2 Reduction By the Solvated Electron Tuned By the Acid Scale
Authors: Mota-Lima Andressa , A. O. do Nascimento Claudio 
Published: July 2021

The electrified plasma/liquid interface (PLI) induces the CO2 reduction (CO2R) by mediation of the solvated electron. Recent theoretical analysis of the chemical reaction network (chemical mechanism) revealed a 100% faradaic efficiency for CO2R [1] provided that the liquid surface was a flowing electrolyte; however, the theoretical analysis did not consider the proton concentration as a chemical variable, or the pH of the electrolyte so to speak, disabling to predict the distribution of products over the entire acid scale. For this reason, in this work, the proton has been categorically considered as a reactant and an essential variable for the dynamical model describing the CO2R via electrified PLI.Two new routes toward formic acid production are proposed namely the disproportionation-like (via-2) and radical cross-combination (via-3) reactions, see figure 1. Both consume the radical H formed by the scavenging of the solvated electron by the proton. The computational results reasonably matched the concentration ratio formate to oxalate around 3.0 for pH 2.45, which features the physical experiments [2]. This ratio would represent 25% selectivity toward formate at pH 2.45 for a flowing-electrolyte experiment. With this reasonably assertive mechanism, it was possible to predict that, at the same conditions of flowing electrolyte, an extremely acid pH (~1) would increase the selectivity toward formate, between 46 and 90% repectivelly for via-2 and via-3.
Fig 1. Chemical reaction networks are shown in the LHS, and the predictions on the concentration ratio oxalate to formate are shown in the RHS for each path of formate synthesis (via–3 and via–2) and both combined.

References

[1] A. Mota-Lima, J.Phys. Chem. C, 124, 10907(2020).
[2] P. Rumbach, R. Xu, and D. B. Go, J. Electrochem.
Soc., 163, F1157 (2016).

Figure 1
(Invited) The Interplay between Thermal and Mechanical Properties in Colloidal Quantum Dot Assemblies
Authors: Wang Robert Y 
Published: July 2021

The ongoing interest in colloidal quantum dot assemblies for real-world electronic and photonic devices necessitates that their thermal and mechanical properties be well understood. Large thermal conductivities are desirable because this minimizes the temperature rise during operation and thereby improves device performance and lifetime. In addition, large elastic moduli and hardness directly impact device durability.
In this talk, I present my group’s findings on two separate correlation regimes between thermal and mechanical properties in colloidal quantum dot assemblies. These two correlation regimes correspond to (i) assemblies with weak inter-particle forces and (ii) assemblies with strong inter-particle forces.
In the weak inter-particle force regime, thermal and mechanical properties intersect via the speed of sound. This stems from the speed of sound being linearly-related to thermal conductivity and quadratically-related to elastic modulus. In the strong inter-particle force regime, thermal and mechanical properties intersect via quantum dot diameter. We find that the quantum dot diameter primarily effects thermal conductivity via the mean free path of the thermal energy carriers. The interrelationship between diameter and mechanical properties in this regime is similar to an effective medium approximation, but with added subtleties. In particular, we find that the surface ligand properties and particle diameter can be intercoupled. This in turn has important impacts on the mechanical properties of the overall quantum dot assembly.
In order to demonstrate the above thermomechanical relationships, I present my group’s combined experimental and modeling studies on three classes of colloidal particle assemblies. First, we use thermal processing methods to study the effect of native oleic acid ligands versus cross-linked oleic acid ligands. Second, we use single-domain superlattices and disordered thin films to study the effect of particle ordering. Lastly, we use ligand exchange methods to study the effect of organic versus inorganic ligands.
Evolution of UV/VIS Photoluminescence of Aged Zn(acac)2 Solutions in Correlation with Carbon Precipitation
Authors: Vasin Andriy V , Kysil Dmitriy V. , Isaieva Oksana F. , Rudko Galina Yu. , Naseka K. M. , Strelchuk Viktor V. , Piryatinski Yuri P, , Sevostianov S. V. , Tertykh V. A. , Savchenko D. V. , Nazarov Alexei N. 
Published: July 2021

Photoluminescent carbon nanodots (CDs), a new class of inorganic nanocarbon materials, have become a significant segments of luminescent nanomaterials in last decade. However mechanism of light emission and detailed identification of the light emitting centers is still debated. A huge number of synthesis methods were suggested, however few of them allow to monitor formation of the CDs on the early stage and development in progress. Recently we have found that zinc acetylacetonat (Zn(acac)2) in ethanol solutions tends to be hydrolysed under room temperature laboratory conditions resulting in gradual conversion of colorless and non luminescent solution to yellowish liquid accompanied by cedimentation of nonluminescent amorphous ZnO:OH. The yellow component of the solution has been identified as dispersion of carbon precipitates. The most important is that the process of hydrolysis in very slow with changing color and PL development within several months. Such a slow process allows following the details of PL development and evolution in time correlation with carbon precipitation.
Ethanol solutions of Zn(acac)2 with concentrations in range of 0.1-4.0 % were prepared and their photoluminescence was monitored for time period of several months. It has been found that early stage of carbon precipitation is resulted in development of relatively narrow PL band with maximum at about 400 nm and corresponding excitation band at 360 nm. The spectrum of the emission band is excitation independent as well as excitation band is not dependent on emission wavelength. In the course of further aging and carbon precipitation the PL band is broaden and shifted to visible range with maximum intensity in range of 420-500 nm depending on excitation wavelength. Detailed emission/excitation study revealed that the visible emission band is composed of at list two components centered at about 420-450 nm and 500 nm, with the corresponding excitation bands at 365 nm and 420 nm. Time-resolved photoluminescence spectroscopy showed that the decay of low energy emission band follows the classical mono-exponential low with the characteristic time of several nanoseconds, while the behavior of high energy component can be described by the stretched exponential low with the average decay time of several nanoseconds. PL data is summarized and discussed in the terms of subnanometer molecular-like carbon emitters and core/shell structural model of amorphous carbon nanoparticles.
(Invited) Non-Blinking Long Lifetime Quantum Dots and Passive Cell Delivery Strategies
Authors: Snee Preston , Emerson Nyssa , Yin Shuhui , Beckwith Joseph , Pálmai Marcell , Jing Haoran , Hu Ying , George Anne , Yang Haw 
Published: July 2021

Over the past ~20 years there has been considerable effort towards the optimization of the photophysical properties of emissive nanomaterials to engender efficacy for biological imaging and sensing. The development of core-shell CdSe/ZnS and CdSe/CdS quantum dots (QDs) was instrumental due to those materials’ resistance to photobleaching and high quantum yields. However, these particles experience fluorescence intermittency (“blinking”), which is detrimental for single particle tracking studies. Furthermore, ~10 nanosecond lifetimes are not compatible with time-gating visualization, a technique that reduces background noise. Last, cytosolic delivery of QDs is a well-known problem due to the propensity for QDs to become sequestered in the endosomes of live cells.
Presented are developments that address these issues. Long lifetimes, >100 ns, and non-blinking behavior have been realized in “giant” quantum dots with a highly alloyed core/shell interface. This results in type-II behavior that separates the electron and hole, which slows emissive recombination. Also presented is a novel cell-penetrating peptide that can be conjugated to surfactants that are commonly employed for QD water solubilization. These materials can be passively delivered to the cytosol of live T-cell lymphocytes. Single particle tracking studies reveal fast diffusion of single dots that are not consistent with endosomal capture, which is observed in control nanomaterials. These developments create new inroads for chemical and biological sensing studies inside of live cells for basic research and diagnostic purposes.

Figure 1
Electrodeposition of Zinc for Redox Flow Batteries
Authors: Magagnin Luca 
Published: July 2021

The redox flow batteries (RFBs) have received great attention due to their attractive features for large-scale energy storage applications. A RFB is a type of flow-based energy storage device capable of providing reversible conversion between electrical and chemical energy through two redox half-cell reactions. Nowadays the most common RFBs exploit the vanadium chemistry, followed by the zinc-bromine chemistries. Though RFB technology has advantage for energy storage and has successful demonstration of systems up to MWh levels, they have not enjoyed broad market penetration. Some of the reasons are relatively high capital and life-cycle costs. New applications are envisaged for RFBs, including the electric mobility which is becoming increasingly important. Zinc based redox flow batteries (Zn-RFBs) based on new chemistries with respect to the chlorine and bromine ones can be the answer to new market success devices, not only in the large storage field but also in the medium and mobility sector.
In this presentation, the electrodeposition of zinc will be discussed in light of its exploitation in the new generation of zinc based RFBs. Alkaline and acidic baths will be presented in combination with proper chemistries for the other half cells. The role of additives and pulse plating will be discussed in terms of nucleation and growth of the metallic layer and its dissolution during charging/discharging cycles. A zinc-iron RFB with low cost and high energy density will be presented. In particular, inorganic electrolytes based on high soluble salts have been developed, achieving a charge density of 30-70 Wh/l. Moreover, in order to enhance the capacity of Zn-Fe flow battery, the use of slurry dispersed electrodes to decuple capacity from the power rating have been studied. As another example, zinc electrodeposition and its optimization will be introduced in combination with the iodine chemistry for high energy efficiency Zn-I RFBs, in the order of 70% at 20 mA cm-2, with high energy density ranging from 25 to 60 Wh/l.
Anodic TiO2 Nanotube Layers As Scaffolds for Deposition of Functional Materials
Authors: Macak Jan M. , Bawab Bilal , Sopha Hanna , Zazpe Raul 
Published: July 2021

The self-organized 1D TiO2 nanotubular layers have attracted considerable scientific and technological interest over the past two decades, all motivated by a great performance in the range of applications including photo-catalysis, solar cells, hydrogen generation and biomedical uses [1,2]. The synthesis of these nanotubular layers has been carried out by a conventional electrochemical anodization of Ti sheet. Except the 1D character, these nanotubes possess unique features such as tunable dimensionality, structural flexibility, unidirectional electron transport through nanotube walls, chemical and mechanical stability and biocompatibility.
One of the major application targets of TiO2 nanotubes has been their utilization as scaffolds or templates for deposition of secondary materials towards new applications [3]. In particular, for the photoelectrochemical applications (e.g. photovoltaics) ordered nanostructures, such as self-organized TiO2 nanotubes, offer the advantage of directed charge transport and controlled phase separation between the donor and acceptor materials, unlike within randomly ordered mesoporous TiO2 supports.
Numerous techniques were utilized for this purpose, such as for example hydrothermal routes, electrodeposition or Atomic Layer Deposition (ALD) techniques. Electrodeposition is very powerful technique to deposit metals [4], oxides [5] or other rather complex materials (such as CuInSe2 [6]) within the nanotubes various by means of complete filling or decoration with. On the other hand, ALD can deposit the widest range of secondary materials within TiO2 nanotubes by means of homogenous coatings [7-10].
The presentation will be focused in detail on TiO2 nanotube layers of various aspect ratios filled, decorated or coated by various materials using electrodeposition. Experimental details and some very recent photo-electrochemical and structural characterizations of a new type of heterostructured photo-chemical cell will be presented and discussed.
References

J.M. Macak et al., Curr.
Opin. Solid State Mater. Sci.,
2007
,
1-2, 3-17.

J.Lee, A. Mazare, P. Schmuki, Chem.
Rev., 2014, 114, 9385-9454

J.M. Macak, Chapter 3 in: D. Losic and A. Santos, Electrochemically Engineered Nanoporous Structures, Springer International Publishing, Switzerland, 2015.

J.M. Macak, B.G. Gong, M. Hueppe, P. Schmuki, Adv. Mater., 2007, 19, 3027.

L.Wu & G. Zangari, J. Phys. Chem. C,
2010, 114, 11551

S.Das & J. M. Macak et al., ChemElectroChem, 2017, 4, 495

R. Zazpe et al, Langmuir, 2016, 32, 10551

S. Ng et al., Adv. Eng. Mater., DOI: 10.1002/adem.201700589

R. Zazpe et al., Nanoscale, 2018, 10, 16601-16612.

F.Dvorak et al., Appl. Mater. Today,
2019
, 14, 1-20.
Pulsed Laser Deposition of Ti-Based MAX Compounds for Next-Generation Wiring Technology
Authors: Wakamatsu Kazunobu , Saito Takeyasu , Okamoto Naoki 
Published: July 2021

Semiconductor wiring technology with a width of 10 nm or less is going in order to realize high performance and high integration of large-scale integrated circuits. Copper is currently used as the main wiring material, however, a barrier layer of TiN is necessary due to high diffusivity of Cu into Si or SiO2. In addition, the resistivity of TiN is ten times higher than that of Cu, which results in a drastic increase with decreasing line width less than 10 nm. Therefore, the development of a barrier layer free wiring material to replace copper should be necessary.
The MAX compounds (M: transition metal element, A: A-group element, X: either carbon or nitrogen) is one of the promising candidates for next generation wiring technology. The stoichiometry of MAX compounds is Mn+1AXn (n = 1~3), and exhibits the properties of both ceramics and metals, and some of the compounds have a low volume resistivity as 10 μΩcm. In this study, pulsed laser deposition of TiSiN and TiGeN were carried out and physical and electrical properties were evaluated.
Targets (TiN : Ti : Ge or Si = 3 : 1 : 1) was bought from TOSHIMA Manufacturing. Al2O3 (001) and 1-μm thickness thermal oxide on Si(001) was used as substrate. Substrate temperature was either room temperature or 600℃. N2 was introduced during deposition. Repetition frequency was fixed at 8 Hz, and laser energy was changed from 25 mJ to 75 mJ. Table 1 and 2 show deposition condition for TiGeN and TiSiN, respectively. X-Ray Diffraction and X-Ray Photoelectron Spectroscopy were used to evaluate the crystallographic structure and composition ratio, respectively. Film thickness was measured by using surface profiler. Electronic properties were measured by four point probe method.
Figure 1 shows XRD pattern of TiGeN film deposited on Al2O3 substrate. When TiGeN was deposited at 600℃ and B.P., peaks ascribed to Ge(111), TiN(111) and TiN(200) were observed. TiN(111) peak position 36.85° from TiGeN is 0.04° higher than that from TiN (111) (36.81°, Card No. 00-006-0642), which suggests that lattice parameter decreased from 2.440 Å to 2.437Å. On the other hand, the peak intensity of TiN(200) from TiGeN deposited at 600℃ becomes clear by introducing N2 to 2.0 Pa. TiN(200) peak positions from TiGeN at 600℃ with 0.02 Pa and 2.0 Pa were 39.30° and 39.35°, respectively, the difference from TiN(200) (42.61°, Card No. 00-006-0642) were 3.31° and 3.26°. This suggests that lattice parameter becomes larger from 2.120 Å, to 2.291 (0.02 Pa) or 2.288 Å (2.0 Pa), respectively. One possible reason could be the incorporation fo Ge into TiN lattice.

Figure 1
Mathematical Modeling of Cyclic Voltammogram Curves of Copper Deposition Involving Multiple Additives
Authors: De Shuvodeep , Huang Qiang 
Published: July 2021

The manufacturing of interconnects and the packaging of integrated circuits are achieved with electrodeposition of copper or other metals. In order to increase the rate of deposition, especially for the large features in packaging, forced convection is provided with certain agitation mechanisms. Although this reduces deposition time, it leads to non-uniform mass transport within each feature and between different features. Special organic additives are used in the solution during the process in order to tune the nucleation and growth of metal, as well as to modify the deposition rate and improve the uniformity. A mathematical model to describe the behavior of organic additives in conjugation with fluid flow and features of various geometry and dimensions is very much desired to facilitate chemistry and process development. In order to achieve this, the physiochemical kinetics of additive and their influence on the Cu deposition rate need to be described precisely.
This presentation focuses on a method to extract the kinetic parameters describing the combined effect of multiple additives during copper deposition using rotating disk electrode (RDE). The one-dimensional steady state convection-diffusion equation for each of the chemical species including copper is solved by a semi-analytical method for a range of potentials. The boundary conditions of these differential equations are coupled on the surface of the RDE through the surface coverage of the absorbed species. The steady state of surface coverage of the species represents a dynamic equilibrium of three key processes i.e., adsorption, desorption, and consumption (incorporation). When equilibrium is achieved, the net rate of adsorption and desorption becomes equal to the rate of consumption. At each value of potential, the surface coverage of the additives is solved. At first, the solution is obtained with only one species known as suppressor and it was found that in a specific range of voltage and kinetic parameter multiple solutions of the surface coverage exist at same applied potential. This mathematically explains the S-shaped negative differential resistance (NDR) feature in experimental Cyclic Voltammogram (CV) curves. Figure 1 shows three such experimental S-shaped curves for different concentration of suppressors. The NDR region obtained in the theoretical CV curve is sensitive to the kinetic parameters of the additives. It is possible to match the theoretical and the experimental CV curves by optimizing the kinetic parameters. Determination of the kinetic parameters by particle swarm optimization using experimental data for multiple additive concentration will be discussed in detail in this talk.

Figure 1
Fully Three-Dimensional Silicon-Integrated Dielectric Capacitor at 1 µFmm-2 for on-Chip Energy Storage
Authors: Paghi Alessandro , Strambini Lucanos , Mariani Stefano , Sood Anjali , Kalliomaki Jesse , Jarvinen Paivi , Toia Fabrizio , Scurati Mario , Morelli Marco , Lamperti Alessio , Barillaro Giuseppe 
Published: July 2021

The increasing request of on-chip energy storage devices is driven by the augmented connectivity between people and things for IoT, portable, and wearable electronic applications. These systems require high performance components with low power consumption, compact size, and high energy storage capability. Supercapacitors (SCs) achieve capacitance density in the order of 0.1–1 mF/mm2. Nonetheless, their poor performance in terms of operation frequency (from Hz to tens of Hz, rarely beyond 1 kHz) and voltage (rarely exceeding 2 V), together with their low compatibility with standard integrated circuit (IC) technologies, have inhibited their integration to date.
Dielectric capacitors (DCs) make use of solid-state dielectrics sandwiched between two conductive electrodes. These capacitors operate at high frequency (up to a several MHz) and voltages (exceeding tens of Volt). However, the areal capacitance of DCs is order of magnitude smaller than that of SCs. The use of high dielectric constant materials (k>10) and the exploitation of the third dimension (3D capacitor) to increase the effective surface area of the capacitor per unit volume have been proposed.
In this work, we successfully address the challenge of achieving a 3D silicon-based dielectric capacitor with high capacitance density and large operation voltage and frequency range, using a fabrication process that is compatible with silicon ICs technology.
Specifically, we report on 3D DCs fully integrated in a silicon chip with areal capacitance up to 1 μF/mm2 by atomic layer deposition of conductive (TiN) and high-k dielectric (Al2O3 and HfAlOX) nanocoatings (20 and 40 nm) into trenches electrochemically etched in silicon with aspect ratio up to 100 [1]. The 3D DCs operate up to 70kHz with an excellent stability with voltage (up to 16V) and temperature (up to 100°C), over 100 h of continuous operation (>108charge/discharge cycles). The 3D DCs exhibit power and energy densities of 566 W/cm2 and 1.7 μWh/cm2, respectively, greater that those of most state-of-the-art dielectric capacitors and supercapacitors.
[1] L. M Strambini, A. Paghi, S. Mariani, A. Sood, J. Kalliomäki, P. Järvinen, F. Toia, M. Scurati, M. Morelli, A. Lamperti, G. Barillaro, Three-dimensional silicon-integrated capacitor with unprecedented areal capacitance for on-chip energy storage, Nano Energy, 68, 104281 (2020)