bluuebunny/crossref_metadata_2025 huggingface dataset:
CVD Synthesis of Graphene Nanomesh on Ge(001)
Authors: Saraswat Vivek , Way Austin , Jacobberger Robert , Arnold Michael
Published: July 2022

Bottom-up synthesis of functional graphene nanostructures on industry-compatible semiconductors such as Si and Ge is the key to unlocking the tremendous potential of graphene in electronic applications. Herein, we demonstrate the growth of graphene nanomesh on Ge using chemical vapor deposition – a technique used widely in the semiconductor industry. Graphene nanomesh is a promsing material in semiconductor electronics because of its ability to simultaneously achieve a large drive current and on/off ratio – one of the key challenges in graphene nanoribbon electronics[1]. However, in order to realize a nanomesh with desired and tunable electrical characteristics – an accurate control over the nanoribbon width, presence of atomically smooth edges, and nanoribbon placement is desired. In the literature, several techniques have been demonstrated to fabricate graphene nanomesh such as top-down lithography[2], bottom-up polymerization[3], and molecule-assisted CVD[4]; yet, a combination of accurate placement, tunable widths and atomically smooth edges has been challenging to achieve. We attempt to overcome this bottleneck by initiating CVD nanoribbon synthesis from deterministically placed arrays of graphene nanoseeds on Ge. We are able to tune the nanoribbon widths by changing the starting seed size and array pitch. The nanoribbons evolved from these nanoseeds fuse into each other when grown long enough – forming a nanomesh. These nanomeshes have atomically smooth edges and exhibit semiconducting characteristics. We also perform extensive simulations to identify the seed-sizes and pitches and demonstrate that this technique allows us to synthesize nanomeshes of desired architecture and electrical characteristics and thus can be used as channel materials in high performance / RF applications as well as BEOL interconnects.

References

Saraswat et al. ACS Nano, 15,3674-3708 (2021)

Bai et al. Nature Nanotechnology, 5, 190–194 (2010)

Moreno et al. Science, 360, 199-203 (2018)

Kim et al. ACS Applied Materials & Interfaces, 13, 28593-28599 (2021)
Development of Anode-Free Metal Batteries
Authors: Zhang Ji-Guang , Cao Xia , LE Phung M-L , Jin Yan , Kim Ju-Myung , Xu Wu
Published: July 2022

Ever increasing need for electrical vehicles (EVs) continually pushes the boundary of high-density energy storage systems. To date, the state of the art of lithium (Li) ion batteries (LIBs) consisting of graphite anode and high voltage Li intercalation cathodes cannot satisfy the energy demand from these applications. By replacing graphite anode with Li metal anode (LMA), specific energy density of Li metal batteries (LMBs) can increase by more than 50% because LMA has a much higher specific capacity (3820 mAh g-1) than that of graphite (372 mAh g-1). To further increase the energy density of Li batteries, the concept of “anode-free” Li batteries (AFLBs) has been explored. Similar approach can also be used in “anode-free” sodium (Na) batteries (AFSBs) to further improve their energy densities. In this work, we will report our recent work on the development of AFLBs and AFSBs. The common challenges in these batteries will be analyzed and compared first. Several approaches, including development of novel electrolytes, substrate treatment, optimization of testing protocol and environment conditions, have been adopted to increase the cycle life of these batteries. At last, future perspective and application of anode-fee metal batteries will be discussed.

References

Niu, C.; Liu, D.; Lochala, J. A.; Anderson, C. S.; Cao, X.; Gross, M. E.; Xu, W.; Zhang, J.-G.; Whittingham, M. S.; Xiao, J.; Liu, J., Balancing interfacial reactions to achieve long cycle life in high-energy lithium metal batteries. Nature Energy
2021.

Zhang, J.-G., Anode-less. Nature Energy
2019,
4 (8), 637-638.

Pereira, N.; Amatucci, G. G.; Whittingham, M. S.; Hamlen, R., Lithium–titanium disulfide rechargeable cell performance after 35 years of storage. Journal of Power Sources
2015,
280, 18-22.

Boyle, D. T.; Huang, W.; Wang, H.; Li, Y.; Chen, H.; Yu, Z.; Zhang, W.; Bao, Z.; Cui, Y., Corrosion of lithium metal anodes during calendar ageing and its microscopic origins. Nature Energy
2021.
(Invited) Theoretical Study on the Excited and Charge-Separated States of Donor-Acceptor-Linked Molecules
Authors: Higashi Masahiro
Published: July 2022

Photoinduced charge separation process plays important roles in various fields such as natural and artificial photosynthesis, solar cell, and light-emitting diode. Toward an understanding of the molecular mechanism of photoinduced charge separation, we have been studying the excited and charge-separated states of donor-acceptor-linked molecules with theoretical methods such as QM/MM method and MD simulation. In this presentation, we will mainly introduce two topics of our research. The first one is porphyrin-fullerene linked molecules. It is experimentally known that the yields of charge-separated states of these molecules is not linear with the bridge length, but reaches a maximum at a specific length. It is also known that the energy of the singlet excited state of this compound is lower in benzonitrile solvent in the following order: local excited state of porphyrin, local excited state of fullerene, and charge separation state. However, by simply using the stable structure of the ground state in the theoretical calculations, the energies of each excited state are in the exact opposite order, and thus the experimental results could not be reproduced. In order to reproduce the experimental results, the structural relaxation of the molecule in the excited state and the response of the solvent are important. However, a simple polarization continuum model of the solvent is insufficient to stabilize the charge separation state. Therefore, we used the QM/MM RWFE-SCF method, which efficiently combines the QM/MM method with MD simulations to optimize the geometry of the solute molecule (QM region) with quantum chemical calculations including the effects of the thermal fluctuations of the surrounding environment such as the solvent molecules (MM region) treated by the molecular mechanics force field. The energy differences calculated with the QM/MM RWFE-SCF method are in good agreement with the experimental results. The charge-separated state is greatly stabilized by solvent molecules due to the large dipole moment. The next topic is acceptor-donor-acceptor type non-fullerene acceptor called TACIC. The excited state of TACIC is known to have a longer lifetime in the film state than in solution. This is in contrast to a similar non-fullerene acceptor molecule, ITIC, which has a shorter lifetime in the film state. However, the molecular mechanism is unknown. We analyzed the structures and excited states of the TACIC and ITIC by using quantum chemical calculations and MD simulation. It is found that the packing structure of TACIC in the film state is much different from that of ITIC, which could be related to the difference in lifetime of the excited state. Further analysis is currently in progress.
(Invited) Advanced Photoresponsive Materials from Porphyrins and Porphyrins: The Metal–Organic Framework Approach
Authors: Woell Christof
Published: July 2022

For the fabrication of macroscopic devices exploiting the properties of organic chromophores, the availability of well-defined thin films of high optical quality is an important prerequisite. Optical absorption properties are often strongly affected by inter-chromophore interactions, and therefore periodic assemblies with low defect densities offer substantial advantages over amorphous compounds. In this context, crystalline reticular networks have recently attracted considerable interest. By appropriate functionalization, most organic chromophores can be converted to function as di- or higher-topic linkers, which can coordinate to metal or metal-oxo centers so as to yield stable, metal-organic frameworks, or MOFs. Of particular interest in this context are light-switchable MOFs. However, the conventional powder form of MOFs obtained using solvothermal approaches, exhibits substantial drawbacks with regard to optical applications, e.g. limited efficiency resulting from absorption and light scattering caused by the (micrometer-sized) powder particles. Providing MOFs in the form of thin films avoids these problems. We have developed a layer-by-layer (lbl) deposition method to produce well-defined, highly oriented and monolithic MOF thin films on a number of different substrates. The resulting films are referred to as SURMOFs [1]. The fabrication of hetero-multilayers containing well-defined hetero-interfaces is rather straightforward with this lbl method. A particularly attractive option it to exploit the porous nature of the MOFs in connection with the lbl method to integrate C60 into SURMOF-based devices, e.g. in the context of photoconductivity [2]. In the context on nonlinear optical properties, using sophisticated assembly strategies were recently used to fabricate non-centrosymmetric SURMOFs with high SHG activity [3].

References:

[1] R. Haldar, L. Heinke, Ch. Wöll, Advanced Materials (2020), DOI: 10.1002/adma.201905227

[2] X. Liu, M. Kozlowska, T. Okkali, D. Wagner, T. Higashino, G. Brenner-Weiß, S. M. Marschner, Z. Fu, Q. Zhang, H. Imahori, S. Bräse, W. Wenzel, C. Wöll, L. Heinke, Angew. Chem. Int. Ed. 2019, 58, 9590

[3] A. Nefedov, R. Haldar, Z. Xu, H. Kühner, D. Hofmann, D. Goll, B. Sapotta, S. Hecht, M. Krstić, C. Rockstuhl, W. Wenzel, S. Bräse, P. Tegeder, E. Zojer, Ch. Wöll, Adv. Mat. 2103287 (2021)
(Invited, Digital Presentation) In silico Photochemical Experiments with Non-Born-Oppenheimer Molecular Dynamics
Authors: Curchod Basile
Published: July 2022

What happens to a molecule once it has absorbed UV or visible light? How does the molecule release or convert the extra energy it just received? Answering these questions clearly goes beyond a pure theoretical curiosity, as photochemical and photophysical processes are central to numerous domains like energy conversion and storage, radiation damages in DNA, or atmospheric chemistry. Different theoretical tools have been developed to address these questions by simulating the excited-state dynamics of molecules [1]. Two examples of such methods include ab initio multiple spawning (AIMS) and trajectory surface hopping (TSH). AIMS describes the dynamics of nuclear wavepackets using adaptive linear combinations of traveling frozen Gaussians [2]. TSH portrays the nuclear dynamics with a swarm of independent classical trajectories that can hop between potential energy surfaces for this task [3].

In this talk, I intend to briefly survey some of our recent work aiming at understanding the approximations underlying AIMS [4] and developing new approximate techniques based on the multiple spawning framework [5]. I will also discuss the application of nonadiabatic methods to unravel photochemical and photophysical processes of interest for photovoltaics.

References

[1] F. Agostini and B. F. E. Curchod, WIREs Comput. Mol. Sci. 2019, 9, e1417.

[2] B. F. E. Curchod and T. J. Martínez, Chem. Rev. 2018, 118, 3305.

[3] J. C. Tully, J. Chem. Phys. 1990, 93, 1061.

[4] B. Mignolet and B. F. E. Curchod, J. Chem. Phys. 2018, 148, 134110; B. Mignolet and B. F. E. Curchod, J. Phys. Chem. A 2019, 123, 3582; L. M. Ibele and B. F. E. Curchod, Phys. Chem. Chem. Phys. 2020, 22, 15183.

[5] B. F. E. Curchod, W. J. Glover, T. J. Martínez, J. Phys. Chem. A 2020, 124, 6133.
Rational Design of Dyes and Donor-Acceptor Type Molecules for Organic Solar Cells
Authors: Imahori Hiroshi
Published: July 2022

Organic solar cells (OSCs) have received considerable attention as clean energy conversion devices because of their lightweightness, cost effectiveness, flexibility, and suitability for roll-to-roll printing. In dye-sensitized solar cells the core structure has included a dye-anchored TiO2 electrode for photoinduced charge separation, while in bulk heterojunction OSCs, the active layer of OSC devices has usually consisted of a mixture of conjugated polymers as donors and fullerene derivatives as acceptors.1,2 In particular, the power conversion efficiency (PCE) of OSCs based on fullerene derivative acceptors has reached over 10%. However, it is difficult to further increase the PCE of fullerene-based OSCs due to their inherent limitations including arduous energy-level tunability and low absorption profile. To enhance the photovoltaic performance of OSCs, nonfullerene acceptors (NFAs) with aromatic fused-ring structures have emerged rapidly in recent years to fabricate high-efficiency OPVs. Compared to traditional fullerene acceptors, NFAs possess several advantages, such as facile synthesis and high absorption profile. Most high-performance NFAs possess acceptor-donor-acceptor (A-D-A) type structures, in which fused multi-ring ladder structures are used as the D unit and 1,1-dicyanomethylene-3-indanone (IC) derivatives as the A unit.

In this talk I will give an overview of our recent studies on rational design and synthesis of novel dyes and nonfullerene acceptors. In paticular, several nonfullerene acceptors possessing different D units have been designed and synthesized to address the relationship between the structure and the photophysical and photovoltaic properties of the A-D-A type nonfullerene acceptors.3-6

[1] T. Umeyama and H. Imahori, J. Mater. Chem. A (Feature Article), 2, 11545-11560 (2014).

[2] T. Umeyama and H. Imahori, Acc. Chem. Res.
52, 2046-2055 (2019).

[3] T. Umeyama, K. Igarashi, D. Sasada, Y. Tamai, K. Ishida, T. Koganezawa, S. Ohtani, K. Tanaka, H. Ohkita, and H. Imahori, Chem. Sci., 11, 3250-3257 (2020).

[4] T. Umeyama, K. Igarashi, D. Sasada, K. Ishida,T. Koganezawa, S. Ohtani, K. Tanaka, and H. Imahori, ACS Appl. Mater. Interfaces, 12, 39236-39244 (2020).

[5] T. Umeyama, K. Igarashi, Y. Tamai, T. Wada, T. Takeyama, D. Sasada, K. Ishida, T. Koganezawa, S. Ohtani, K. Tanaka, H. Ohkita, and H. Imahori, Sus. Energy Fuels, 5, 2028-2035 (2021).

[6] T. Umeyama, T. Wada, K. Igarashi, K. Kato, A. Yamakata, T. Takeyama, Y. Sakamoto, Y. Tamai, H. Ohkita, K. Ishida, T. Koganezawa, S. Ohtani, K. Tanaka, and H. Imahori, ACS Adv. Energy Mater., in press.
Hot Electron Extraction Enabled By Single-Crystal Metal Films and Nanostructures
Authors: Leach Gary W. , V. Grayli Sasan , MacNab Finlay , Zhang Xin , Kamal Saeid
Published: July 2022

In contrast to conventional photovoltaic devices which rely on bulk semiconductor material absorption and separation of electron-hole pairs, surface plasmon-based solar energy harvesting employs rectifying metal/dielectric interfaces to capture light and separate charges. Here, we describe the requirements for efficient hot electron extraction in plasmonic photovoltaic devices and demonstrate a new scalable and environmentally friendly electroless deposition method for single-crystal epitaxial noble metals films and nanostructures. The method produces ultra-smooth, low loss, single-crystal noble metal films ideal for subtractive patterning of nanostructures through ion beam milling, and high definition, sub-wavelength single crystal nanostructures through lithographic patterning methods. We describe the nucleation and growth of these metal films and nanostructures in the absence and presence of anionic shape-control agents and examine the role of specific anions in determining the resulting film and nanostructure morphologies via scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). These effects have been exploited to yield large area patterned, and shape-controlled nanoarrays of single crystal metal nanostructures for plasmonic and metamaterial applications. These approaches offer new and cost effective routes to achieve crystalline, shape-controlled surface nanostructure to enable efficient hot electron extraction for energy harvesting and catalysis applications and new noble metal alloys for improved electrocatalysis.
(Invited, Digital Presentation) Synthesis of Multi-Metallic Clusters Using a Dendrimer Reactor
Authors: Yamamoto Kimihisa
Published: July 2022

Dendrimers are highly branched organic macromolecules with successive layers or “generations” of branch units surrounding a central core. Organic inorganic hybrid versions have also been produced, by trapping metal ions or metal clusters within the voids of the dendrimers. Their unusual, tree-like topology endows these nanometer-sized macromolecules with a gradient in branch density from the interior to the exterior, which can be exploited to direct the transfer of charge and energy from the dendrimer periphery to its core.

We show that tinchloride, SnCl2 and FeCl3 complexes to the imines groups of a spherical polyphenylazomethine dendrimer in a stepwise fashion according to an electron gradient, with complexation in a more peripheral generation proceeding only after complexation in generations closer to the core has been completed. By attaching an electron-withdrawing group to the dendrimer core, we are able to change the complexation pattern, so that the core imines are complexed last. By further extending this strategy, it should be possible to control the number and location of metal ions incorporated into dendrimer structures, which might and uses as tailored catalysts, building blocks, or fine-controlled clusters for advanced materials. The metal-assembly in a discrete molecule can be converted to a size-regulated metal particle with a size smaller than 1 nm as a molecular reactor. Due to the well-defined number of metal clusters in the subnanometer size region, its property is much different from that of bulk or general metal nanoparticles. The chemistry of metal clusters on the sub-nanometer scale is not yet well understood because metal clusters, especially multi-metallic clusters, are difficult to synthesize with control over size and composition. The template synthesis of multi-metallic sub-nanoclusters is achieved using a phenylazomethine dendrimer as a macromolecular template.
(Invited) Light Driven H2 Generation in Pt-Tipped CdS Nanorods: Dependence on the Pt Size and CdS Rod Length
Authors: Lian Tianquan
Published: July 2022

Colloidal quantum confined semiconductor-metal nano-heterostructures are a promising class of photocatalysts for solar energy conversion. In these photocatalysts, the semiconductor domain serves as the light absorber and the metal as the catalyst. Such photocatalysts combine the superior light absorption and charge transport properties of the semiconductor with the superior catalytic activity and selectivity of the metal. Furthermore, both domains can be independently tuned to enhance the photocatalytic performance of the heterostructure. Among various semiconductor/metal heterostructures, metal-tipped colloidal semiconductor nanorods (such as CdS-Pt), have attracted extensive interest because they have been reported to have high quantum efficiencies of light driven H2 generation and their morphology can be systematically tuned. The overall light driven H2 generation process involves multiple elementary charge separation and recombination steps in the semiconductor and across the semiconductor/metal interface as well as proton-coupled electron transfer reactions at the catalytic center. The change of the semiconductor or metal domains can often have effects on multiple competing processes involved in the overall reaction. As a result of these complexities, the mechanisms for the morphological dependence of the observed H2 generation efficiencies are not fully understood, hindering the rational design of these photocatalysts. In this talk, we use Pt tipped CdS nanorods (CdS-Pt) as a model system to examine the effect of Pt size and CdS rod length on their light driven H2 generation efficiency. We show that increasing the Pt particle size increases the overall H2 generation quantum efficiency through both increasing the rate of electron transfer from the CdS to Pt and enhancing the efficiency of water/proton reduction; H2 generation efficiency increases at longer CdS rod length by suppression of charge recombination across the Pt/CdS interface. Our work demonstrates that through systematic in situ study of elementary processes involved in the overall H2 generation, it is possible to rationally design and improve semiconductor-metal hybrid photocatalysts.
Can Something that is Called “Sub” be Superb? The Case of Subphthalocyanines
Authors: Torres Tomas , López-Serrano Elisa , Gomez-Gomez Marta , Mateo Luis M. , Labella Jorge , Bottari Giovanni , Ince Mine
Published: July 2022

Subphthalocyanines (SubPcs) are well-known cone-shaped chromophores consisting on three 1,3-diiminoisoindole units assembled around a boron atom. As a result of their 14 pi-electron aromatic core and their tetrahedral geometry, SubPcs exhibit outstanding physical and optoelectronic properties (e.g., strong dipole moment, excellent light absorption in the 550-650 nm, rich redox features, and excellent charge transport capabilities), that have been skilfully used in variety of applied fields, such as molecular photovoltaics, among others. SubPcs were used by us as non-fullerene acceptors in bulk heterojunctions (BHJ) solar cells. On the other hand as part of our systematic investigation in the preparation and study of novel SubPc-based D–A systems, we have used 1,1,4,4-tetracyanobuta-1,3-diene (TCBD) as partner for SubPcs. Moreover, in the case of unsymmetrically substituted SubPcs (i.e., prepared by cyclotrimerization of a phthalonitrile with no C2v symmetry), they present inherent chirality and the corresponding couple of enantiomers can be isolated Columnar aggregates based on chiral SubPcs have been also prepared, giving rise to ferroelectric self-assembled molecular materials showing both rectifying and switchable conductivity. These chromophores have been incorporated in multicomponent systems showing a panchromatic response and allowing the tuning and controlling intramolecular FÖRSTER Resonance Energy Transfer for Singlet Fission.
Ultrafast Charge-Transfer in Panchromatic, Push-Pull Porphyrin-Tetracyanobuta-1,3-Diene-Donor Conjugates
Authors: Dawson Andrew , Sekaran Bijesh , Jang Youngwoo , Misra Rajneesh , D'Souza Francis
Published: July 2022

Light-induced electron transfer is a key step in solar energy conversion, and a process with myriad relevance in the fields of artificial photosynthesis, photocatalysis, photoconductivity, and molecular photovoltaics. In a donor-acceptor, D-A system, light absorption by a chromophore results in the formation of an excited state species, followed by a charge transfer between an electron donor (D) and an electron acceptor (A) leading to a charge-separated D
.+
-A
.-
species.The optimization of these processes and comprehending their mutual interplay to ultimately achieve charge-separated species is of paramount importance for the development of efficient systems in solar light conversion schemes. As part of our continued effort in this field of research,1-3 using a combination of cycloaddition-retroelectrocyclization reaction, free-base and zinc porphyrins (H2P and ZnP) are decorated at their b-pyrrole positions with strong charge-transfer complexes, viz., tetracyanobuta-1,3-diene (TCBD)-DONOR as a novel class of push-pull systems.4 The physicochemical properties of these compounds have been investigated using a range of electrochemical, spectroelectrochemical, DFT as well as steady-state and time-resolved spectroscopic techniques. Charge transfer interactions between the porphyrin and the electron-withdrawing TCBD directly attached to the porphyrin p-system extended the absorption well into the near-infrared region. The occurrence of photoinduced charge transfer and separation has been established by complementary transient absorption spectral studies followed by global and target data analyses. The role of central metal in the porphyrin cavity and the nature of the donor in governing these photo events will be discussed.

Khan, Y. Jang, Y. Patil, R. Misra, and F. D’Souza, Photoinduced Charge Separation Prompted Intervalence Charge Transfer in a Bis(thienyl)diketopyrrolopyrrole Bridged Donor-TCBD Push-Pull System (hot article), Angew. Chem. Int. Ed.
2021, 60, 20518–20527.

S. Yadav, A. Z. Alsaleh,R. Misra and F. D’Souza, ‘Excited State Charge Transfer Leading to Charge Stabilization via an Electron Exchange Mechanism in Symmetric, Central Triphenylamine Derived, Dimethylaminophenyl-Tetracyanobutadiene Donor-Acceptor Conjugates, Chem. Sci. 2021, 12, 1109-1120.

Pinjari, A. Z. Alsaleh,Y. Patil, R. Misra and F. D’Souza, Interfacing High-Energy Charge Transfer States to a Near-IR Sensitizer for Efficient Electron Transfer upon Near-IR Irradiation’ Angew. Chem. Int. Ed. 2020, 59, 23697-23705.

Sekaran, A. Dawson, Y. Jang, K. V. MohanSingh, R. Misra and F. D’Souza, Charge-Transfer in Panchromatic Porphyrin-Tetracyanobuta-1,3-diene-Donor Conjugates: Switching the Role of Porphyrin in the Charge Separation Process, Chem. Eur. J. 2021, 27, 14335-14344

Figure 1
Molecular Engineering of Low-Bandgap Porphyrins for Highly Efficient Organic Solarcells
Authors: Cuesta Virginia , Vartanian Maida , de la Cruz Pilar , Sharma Ganesh D , Langa Fernando
Published: July 2022

Organic solar cells (OSCs) based on solution-processed bulk heterojunction (BHJ) active layers have emerged as promising solutions for the conversion of solar energy into electrical energy in building and indoor applications due to their unique advantages, such as being lightweight and semitrans-parent and the possibility of being processed by low-cost roll-to-roll methods. The BHJ active layer employed for OSCs consists of a blend of an electron-donating material and an electron-accepting material creating internal donor-acceptor heterojunctions, and their optical and electrochemical properties are very important for the realization of a high-power conversion efficiency (PCE).

The optical and electrochemical properties of porphyrins can be adjusted by molecular design and functionalization on the b or meso positions of the porphyrin ring as well as by introduction of different central metal ions.

Although the pioneering use of porphyrins in OSCs was disappointing, as reported efficiencies were very low;the situation has changed over the last five years as Zn-porphyrins with ABAB structures linked to acceptor units, having relatively long-lived singlet excited states, have been successfully used as donors or acceptors, resulting in increased efficiencies.

Here, I´ll present our recent work in design, synthesis, and application of porphyrin-based small molecules for highly efficient OSCs with VOC>1V and PCE>15%.

References

V. Cuesta, M. Vartanian, P. de la Cruz, R. Singhal, G. D. Sharma and F. Langa, J. Mater. Chem. A,2017, 5, 1057.

S. Arrechea, A. Aljarilla, P. de la Cruz, M. K. Singh, G. D. Sharma, F. Langa. J. Mater. Chem. C,

2017, 5, 4742.

M. Vartanian, R. Singhal, P. de la Cruz, S. Biswas, G. D. Sharma and F. Langa, ACS Appl. Energy

Mater. 2018, 1, 1304.

M. Vartanian, P. de la Cruz, F. Langa, S. Biswas, G. D. Sharma. Nanoscale, 2018, 10, 12100.

M. Vartanian, R. Singhal, P. de la Cruz, G. D. Sharma, F. Langa, Chem. Commun,
2018, 54, 14144.

V. Cuesta, R. Singhal, P. de la Cruz, G. D. Sharma, F. Langa, ACS Appl. Mater. Interfaces, 2019, 11, 7216 .

Cuesta, R. Singhal, P. de la Cruz, G. D. Sharma, F. Langa, ChemSusChem
2021, 14, 3439.

H. Dahiya, V. Cuesta, P. de la Cruz, F. Langa, G. D. Sharma ACS Appl. Energy Mater. 2021, 4, 4498.
Ordered Arrangement of Charged Porphyrins in π-Electronic Ion-Pairing Assemblies
Authors: Maeda Hiromitsu
Published: July 2022

π-Electronic ions with appropriate geometries and peripheral substituents provide assemblies through the interactions between charged building subunits, resulting in fascinating electronic properties. Structures and properties of the assemblies can be controlled by the combined negatively and positively charged species in the assemblies. Thus far, diverse π-electronic ions along with ion-responsive π-electronic systems have afforded dimension-controlled ion-pairing assemblies as crystals, supramolecular gels, and thermotropic liquid crystals.[1] Highly ordered arrangement of charged species has been found to be a key factor to exhibit the enhanced performance as fascinating electronic materials. In fact, ion pairs of porphyrin–AuIII complexes as π-electronic cations, prepared with the combination of various anions including π-electronic anions, formed dimension-controlled assemblies as thermotropic liquid crystals, whose ionic components were highly organized by
i
π–
i
π interactions (mainly electrostatic and dispersion forces).[2] Furthermore, π-electronic ion pairs comprising porphyrin-based π-electronic anions[3] have exhibited characteristic assembling modes via
i
π–
i
π interactions and resulting electronic properties such as solid-state absorption, which was correlated with the arrangement of constituent charged π-systems, and photoinduced electron transfer.[4]

References

[1] Recent reviews: (a) Haketa, Y. et al. Mol. Syst. Des. Eng.
2020, 5, 757; (b) Yamasumi, K. et al. Bull. Chem. Soc. Jpn.
2021, 94, 2252. [2](a) Haketa, H. et al. iScience
2019, 14, 241; (b) Tanaka, H. et al. Chem. Asian J.
2019, 14, 2129; (c) Tanaka, H. et al. Chem. Asian J.
2020, 15, 494; (d) Fumuto, N. et al. Org. Lett.
2021, 23, 3897; (e) Kuno, A. et al. Chem. Eur. J.
2021, 27, 10068. [3](a) Sasano, Y. et al. Dalton Trans.
2017, 46, 8924. (b) Sasano, Y. et al. Chem. Eur. J.
2019, 25, 6712. [4] Sasano, Y.; Tanaka, H. et al. Chem. Sci.
2021, 12, 9645.
Probing the Nitrite Reductase Activity of Heme-Copper Respiratory Oxidase
Authors: Varotsis Constantinos , Pinakoulaki Eftychia
Published: July 2022

Heme-copper oxidases, in particular cytochrome ba
3, is capable of reducing NO to N2O and oxidizing CO to CO2, although with a low activity. Despite the very low (20%) overall sequence homology to other structurally known cytochrome c oxidases, the four redox centers of cytochrome ba
3 display high similarity with those of other oxidases. Extensive studies, at ambient temperatures, have shown that the heme a
3-CuB binuclear center of fully reduced (FR) and mixed valence (MV) cytochrome ba
3 is subjected to peculiar thermodynamic and kinetic properties, with significant deviations, relative to the mesophilic aa
3-type oxidases. These properties include an increased hydrophobicity, a high affinity of CuB for exogenous ligands such as CO (K > 104 M-1) and a slow intramolecular ligand transfer to heme a
3 (k = 8 s-1). As a result, cytochrome ba
3 is the only documented oxidase where the binding of CO to CuB is exergonic and accounts for 25-30% of the total enzyme concentration. Furthermore, the proximal and the distal environment of heme a
3 shows a high structural flexibility evidenced from the multiple heme a
3 Fe2+-CO conformers detected in both the FR and MV forms of the enzyme. Time-resolved step-scan FTIR studies showed that after photolysis of CO from heme a
3
2+ the ligand is almost quantitatively transferred to CuB
1+ and the transiently formed CuB
1+-CO complex exhibits an unusual long lifetime of 20 ms (pD 8.50). In addition, the midpoint redox potentials of hemes b and a
3 have been reported in three different studies being inverted, with values of 210/213 and 430/285 mV (versus Normal Hydrogen Electrode (NHE)), respectively. Resonance Raman and FTIR studies of the ligand binding properties of heme-copper oxidases will be presented.

References.

Discrete Ligand Binding and Electron Transfer Properties of ba
3-Cytochrome c Oxidase from Thermus thermophilus: Evolutionary Adaption to Low Oxygen and ...C Koutsoupakis, T Soulimane, C. Varotsis Accounts of chemical research 52 (5), 1380-139, 2019.

The structure of a ferrous heme-nitro species in the binuclear heme a3/CuB center of ba
3-cytochrome c oxidase as determined by resonance Raman spectroscopy Loullis, MR Noor, T Soulimane, E Pinakoulaki Chemical Communications 51 (2), 286-289, 2015.
Electrochemical Behavior of Li−CNT Composite Powder Electrodes for Stable Lithium Anodes
Authors: Yang Seung Hoon , Yoon Woo Young
Published: July 2022

Li metal is considered a highly desirable anode material for next-generation high-energy-density rechargeable lithium batteries because of its extremely high specific capacity (3860 mAh g-1), large negative standard reduction potential, low mass density, and ability to enable battery chemistries with lithium free cathode materials. However, the practical application of Li metal anodes is still prohibited by its low Coulombic efficiency, uncontrolled dendritic growth, and poor solid electrolyte interphase (SEI) during the Li dissolution /deposition. Here, A new type of Li−CNT composite powder electrode (Li−CNT CE) was fabricated via mechanical blending of Li powders and CNT Ball produced by a spray dryer. The Li-CNT CE can suppress dendrite formation with its isolated Li powder and low current density caused by the large specific surface area of spherical Li powder. In our cycle life test of symmetric Li-CNT CE, void spaces between spherical Li powders and CNT Balls contributes to stable longer cycling properties, which works for more than 1000h, because it inhibits inevitable volume changes. Moreover, high electrical conductivity of CNT ball and lighter battery weight due to low mass density of CNT ball is sure of an advantage for the automotive battery. This work provides new insights into the development of Li powder and CNT Ball composite electrode for achieving dendrite-free, high CE and Low mass density Li-metal anodes in Li metal secondary battery (LMSB).
Understanding the Electrolyte/Electrode Interfacial Interactions for the Development of High-Performance Aqueous Redox-Enhanced Electrochemical Capacitors
Authors: Kim Sung Won , Cho Young Hun , Kim Dahye , Yoo Seung Joon
Published: July 2022

Research in electrochemical energy storage is converging to target systems with battery-level energy density, and capacitor-level cycling stability and power density. One approach is to utilize redox-active electrolytes that add faradaic charge storage to increase energy density of supercapacitors. Aqueous redox-active electrolytes are simple to prepare and to up-scale; and, can be synergistically optimized to fully utilize the dynamic charge/discharge and storage properties of micro/mesoporous carbon based electrode systems. However, aqueous redox-enhanced electrochemical capacitors (redox ECs) have performed relatively poorly, primarily due to the cross-diffusion of soluble redox couples, reduced cycle life, and low operating voltages.

In this presentation, we show that these challenges can be met by the use of liquid-to-solid phase transitions of redox electrolyte molecules, and their reversible confinement in the pores ( > 2 nm) of high-surface-area electrodes. This approach is demonstrated by the use of bromide catholyte and modified hydrophobic cations (e.g., viologens and tetrabutylammonium) that together induce reversible solid-state complexation of Br2/Br3
–. This mechanism solves the cross-diffusion issue of redox ECs without using costly ion-selective membranes, and has the added benefit of stabilizing the reactive bromine generated during charging.

Using the concepts learned from this 1st generation configuration, we further developed high-performance aqueous-based redox ECs by (1) synthesizing differently functionalized/substituted viologen molecules and (2) optimizing the interfacial interactions between the viologens and hierarchically porous-structured carbon electrodes. In the second part of this presentation, we show systematic approaches to explore optimal parameters to improve the energy storage capacity of the device.
Application of Machine Learning Algorithms to Classify and Predict Corrosion Behavior of Stainless Steels in Lactic Acid
Authors: Hakimian Soroosh , Pourrahimi Shamim , Hof Lucas
Published: July 2022

Corrosion of metals is a critical issue, which causes a considerable amount of loss in industries. There are numerous factors that can influence corrosion, including chemical composition and multiple environmental conditions. Hence, it is difficult to determine the relation between individual environmental factors and corrosion processes based on physics-based corrosion laws or to predict the corrosion life of materials. Predicting corrosion behavior of materials in any type of environment is important since testing materials in each different environment is time-consuming and expensive. Hence, analyzing corrosion data and, subsequently, predicting corrosion behavior needs advanced data mining methods. Recently, machine learning (ML) methods have been extensively used in materials research thanks to their powerful data mining capabilities. By learning from sample data and experience, it automates the searching for knowledge without reliance on predetermined equations. In corrosion research, machine learning algorithms such as random forest, support vector regression, and artificial neural networks have been used to study the corrosion behavior.

Stainless steels are widely used in corrosive environments. This research aims to develop classification methods for predicting stainless steel corrosion behavior in different concentrations of lactic acid and different temperatures. The Handbook of corrosion data was used to gather data on stainless steel corrosion in lactic acid. Outlier, repeated, and missing data were treated during a pre-processing step (Figure 1). Based on the ML results, we can properly predict the corrosion behavior of various grades of stainless steels, in different lactic acid concentration and test temperatures. The best training and testing accuracies are 98.73% and 90.00%, respectively, which are obtained by fitting the decision tree classifier. It is also concluded that the percentage of four essential elements (C, Cr, Ni, Mo) in stainless steel alloys, alongside acid concentration and temperature, can be used as the input data to predict the corrosion behavior. Receiver operating characteristic (ROC) curves indicate that stainless steels with poor corrosion behavior are correctly classified by support vector machine (SVM) multiclassification modeling. Therefore, the SVM algorithm is reliable for detecting stainless steels with poor corrosion behavior, which are highly risky for critical applications if chosen incorrectly.

Figure 1
(Digital Presentation) Multiscale Understanding of Local Structure-Dependent Hydrogen Incorporation in TiO2
Authors: Keilbart Nathan Daniel , Song Youngil , Zhu Yakun , Kweon Kyoung E. , Rodriguez Jennifer , Qiu Roger , Heo Tae Wook , Wood Brandon C.
Published: July 2022

Hydrogen interaction with metal oxides is an important phenomenon that affects all vital areas of industry such as aerospace, transportation, and commercial applications. The metal oxide provides a naturally forming protective layer against dissolution of the underlying metal. It has been reported that hydrogen is still able to percolate through this protective layer traveling all the way to the metal to form a corrosive brittle metal hydride. There have been many studies looking to understand the interaction of hydrogen at the surface but an in depth look at the surface to bulk transition of hydrogen through a metal oxide for all representative phases of an oxide is minimally represented in the literature. For the focus of our study, we employed a multi-scale approach combined with experimental studies to explore the different phases of titania (TiO2) which includes rutile, anatase, and an amorphous phase. A thermodynamic analysis of the stability for hydrogen was considered using density functional theory (DFT) starting at the low energy surface facets to the bulk. For the amorphous phase, the binding energy was analyzed as a function of the hydrogen content and oxygen coordination environment. Temperature programmed desorption (TPD) experiments provided a direct comparison with theory. Additionally, NMR simulations validified the generated amorphous phase which agreed well with experimental data. The material properties computed using DFT were used in combination with experimental results to parameterize a mesoscale model. Several environmental conditions were analyzed consisting of grain size, temperature, and grain boundary properties. Further work investigated crystalline titanium (Ti) in the bulk and at several grain boundaries to elucidate possible initiation stages of hydride formation.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Corrosion Performance of Additively Manufactured 316L Stainless Steel Produced By Feedstock Modification
Authors: Vukkum Venkata Bhuvaneswari , Darwish Ahmed A , Christudasjustus Jijo , Storck Steven , Gupta Rajeev Kumar
Published: July 2022

Additive manufacturing (AM) is an emerging technology that can build 3d-component in a single step via the layer-by-layer process. Selective laser melting (SLM) is a popular powder bed fusion (PBF) – AM technique that involves rapid heating and cooling cycles with broad temperature gradients and complex thermal history. Moreover, the SLM components are often reported to have lower build densification due to stochastic porosity. The complex thermal cycles and stochastic porosity can negatively influence the corrosion performance of SLM printed 316L Stainless steel (SLM-316L) alloys. The corrosion performance of SLM-316L can be improved by optimizing the SLM processing parameters to improve the density and/or performing post-processing. However, post-processing increases the cost and time to deliver the components and is desired to avoid. Therefore, modifying the feedstock to increase corrosion resistance and therefore tolerance of the pores would help streamline the workflow and eliminate expensive post-manufacturing steps. In this research, the feedstock modification was conducted using ball milling of various additives and 316L powder. Corrosion performance of the SLM specimen was dependent on the additive used to modify the feedstock. Some of the additives imparted significantly improved corrosion performance, as evident from the high pitting and repassivation potentials and absence of metastable pitting. Observed corrosion performance was correlated with the microstructure which was studied using scanning and transmission electron microscopes. X-ray photoelectron spectroscopy and time of flight secondary ion mass spectrometry was used to study the surface film. Role of additives on microstructure and corrosion performance will be discussed.
Effect of the Microstructure on the Corrosion and Fatigue Behavior of the Additively Manufactured M789 Stainless Steel
Authors: Yassine Sarah , Laliberté-Riverin Simon , Mena Morcillo Emmanuel , Cova Matteo , Brochu Myriam , Mauzeroll Janine
Published: July 2022

Corrosion is one of the most destructive on the environment and also on our safety. Not only does the microstructure influence the severity of corrosion, but also does many other chemical and mechanical factors such as fatigue. For this reason, the ability to evaluate and further predict localized corrosion on materials subjected to stress has been a growing interest in an attempt to foresee the fatigue-corrosion damage before escalating into a material failure, years later.

A quantitative and qualitative investigation was conducted to assess the effect of the heterogeneous microstructure on the fatigue and corrosion resistance of the additively manufactured martensitic stainless steel, AMPO M789, employed in application where a high hardness and corrosion resistance is of need. We first examined quantitatively the inclusion content of polished surfaces and the roughness of net-shaped samples, in order to estimate the fatigue strength of the alloy with statistics of extreme values and linear fracture mechanic approach. We then exposed the material to electrochemical tests in synthesized seawater, in order to identify possible corrosion mechanisms and to further assess the pits initiation and their dimensions. Considering those results, we finally predicted a possible performance of M789 in high-cycle fatigue in presence of corrosive environment. We believe our work represents a first step towards studying the synergistic effect of localized corrosion and fatigue strength on the heterogeneity of this new additively manufactured alloy.
Novel Magnesium Protective Coatings Offering Excellent Corrosion Performance
Authors: Valdez Lyanne , Allen Kristi M , Harris Rachel , Rock Reza
Published: July 2022

There has been a growing interest in using magnesium alloys in automotive, industrial, and aerospace applications due to their low density, high strength-to-weight ratio, good machinability, and low cost. These alloys have the potential to lighten cars and aircraft, reducing their fuel consumption and emissions. A major drawback to magnesium alloys is their highly reactive nature, which results in corrosion. Through a project administered by the U.S. Automotive Materials Partnership (USAMP), PPG focused on the development of metal pretreatment solutions for different magnesium alloys to address the reactivity challenge, while eliminating the use of chromium, a carcinogenic and environmentally toxic corrosion inhibitor used in existing magnesium pretreatment solutions. A major technical advance was accomplished by creating several chromium-free cleaning and pretreatment processes that offer excellent corrosion protection when compared to a typical automotive pretreatment to combat magnesium’s reactive nature. This work also concentrated on optimizing the pretreatment solutions by making them compatible with magnesium and other metals without the need for additional process steps, enabling the use of magnesium in more multi-metal applications and greatly expanding utilization opportunities.
(Digital Presentation) Formation Mechanism and Defects of Electrodeposited Ca-P Coating on Biodegradable Mg-Zn-Ca Alloy
Authors: FU Shian-Hwu , Chu Peng-Wei
Published: July 2022

Biodegradable implants are a new concept to substitute current nondegradable medical materials. The biodegradable implant can decompose in the patients’ body when the treatment is finished and be discharged through metabolism. Mg alloys, with their biocompatibility and high reactivity, meet the requirements of a biodegradable material. Also, Mg has a similar density to the human bones and the lowest elastic modulus among the structural metallic biomaterials, which can mitigate the stress shielding effect. For Mg-Zn-Ca alloys, besides the merits of Mg, Zn is related to bone metabolism and osteopathic phosphate activity, while Ca is the main element of bones that is essential for the synthesis of bone compounds. However, the degradation rate of Mg alloy implants needs to be controlled, or the implant may corrode too fast, causing local hydrogen accumulation and alkalization that hurts the patients. One of the effective ways to improve the alloy corrosion resistance is by coating. Ca-P coatings, such as brushite (dicalcium phosphate dihydrate, DCPD) and hydroxyapatite (HA), can mitigate the degradation rate of Mg alloys and show good biocompatibility and osseointegration. Electrodeposition is a simple way to synthesize coatings on metallic materials with an easy experimental set-up, and the process parameters are highly controllable.

Even though there are plenty of reports about the fabrication of Ca-P coatings on Mg alloys through electrodeposition, few of them focus on the film formation mechanism. Issues related to coating defect formation and inhomogeneity are rarely discussed. Therefore, this report focuses on the film formation mechanism and the relationship to the defects of the electrodeposited DCPD coating on a Mg-2.5wt%Zn-1wt%Ca alloy. By altering the deposition potential, the reduction reactions that proceed on the substrate are different. The involvement of H2O reduction affects the formation of DCPD and changes the microstructure of the coating. Combining electrochemical tests and microstructure analysis, the corrosion properties of the coatings are measured, and the results are linked to the difference in film microstructure and defects. With SEM/FIB cross-sectional observations, the formation mechanism of the coatings and the relationship to the process condition will be discussed. The degradation rate of Mg alloys can be tuned by understanding the DCPD film formation mechanism and the cause of the defects.