bluuebunny/crossref_metadata_2025 huggingface dataset:
Ionic 2D Materials
Authors: Ruiz Eliseo
Published: August 2024

2D materials are an exciting topic with a wide variety of applications in many research fields, from optoelectronics, photonics or qubit devices to catalysis. So far, these layered nanoscopic materials have been obtained by different procedures. In top-down approaches, from simple mechanical "Scotch tape" exfoliation to liquid exfoliation to break the weak non-covalent interactions between layers. In this project, the challenge was to obtain 2D flakes of a 3D ionic starting material with cubic rock salt structure (e.g. alkali halides NaCl, NaF, KCl, KF or CsF). They will have physical properties with substantial differences from those of known 2D materials. For example, there are few large bandgap 2D materials, almost exclusively BN layers. The BN bulk system has a band gap around 4 eV and its monolayer 6 eV, while the employed alkali halides in this project, the bulk vales are 10.0 eV (CsF), 10.9 eV (KF), 11.7 eV (NaF), KCl eV (8.5) and eV NaCl (8.6). This will open many applications that are now only restricted to BN layers. The crucial point is how it is possible to exfoliate an isotropic 3D material with ionic interactions in three spatial directions.(1,2) The intercalation of bromine molecules in CsF was corroborated, many years ago, by X-ray single-crystal diffraction.(1,3, see Figure) The intercalated structure is analogous to that of other conventional 2D materials; for example, graphene also with bromine molecules. This intercalation into the 3D structure of the alkali halide has two effects, one is to generate an anisotropic 2D structure with alternated monoatomic CsF layers and layers of Br2 molecules. The second important effect is that now for the exfoliation of the CsF-Br2 compound, only the non-ionic F···Br-Br interactions must be broken. Preliminary DFT calculations indicate that such contact energies are of the same order of magnitude as other non-covalent interactions of common 2D materials.

The intercalation of such 2D materials has been performed by the intercalation of Br2 and IBr molecules combined with different exfoliation techniques (sonication-centrifugation, ball milling, microwaves..). The characterization of the 2D flakes has been performed using Atomic Force Microscopy. The final goal of this project is to make a profit from the large gap of such 2D systems for optoelectronic properties, such as single-photon emission.

(1) Desmarteau, D. D.; Grelbig, T.; Hwang, S. H.; Seppelt, K., Angewandte Chemie-International Edition in English
1990,
29 (12), 1448-1449

(2) Ruiz, E.; Alvarez, S., Journal of the American Chemical Society
1995,
117 (10), 2877-2883.

(3) Drews, T.; Marx, R.; Seppelt, K., Chemistry-a European Journal
1996,
2 (10), 1303-1307.

Figure 1
In Situ transmission Electron Microscope Observation of Biased-Induced Dynamic Evolution of Two-Dimensional CrS2
Authors: Chou Pin-Yu , Sung Hsin-Ya , Wu Wen-Wei
Published: August 2024

Two-Dimensional transition-metal dichalcogenides (2D-TMDs) have attracted great attention recently owing to their potential to become the important material for next generation semiconductor devices. While using the device, it needs to ensure high density current and biased voltage for a long time. However, the study on TMDs in high-energy environment is insufficient. In this work, the phase evolution of CrS2 are revealed via in-situ biasing experiments and recorded by transmission electron microscope (TEM) at atomic scale. The ultra-thin layered (~1.6nm) CrS2 was synthesized through atmospheric pressure chemical vapor deposition (APCVD), followed by transferring the as-grown samples onto specialized TEM electrical chips. The TEM characterization of CrS2 initial sample provided the basic understanding of this Cr-based TMD, identified as pure 1T phase with single crystal structure as shown in Figure 1. The advanced in situ technique was employed to record the structural evolution and was tested the endurance of CrS2 during biasing. Moreover, the results can make significant contributions to future semiconductor device designs and demonstrate CrS2 has great potential as a semiconductor device with its outstanding characteristic of biased-endurance.

Figure1. (a) Low-magnification TEM image of 1T-CrS2. (b) High-resolution TEM image of 1T-CrS2, corresponding with FFT along [001] zone axis. (c) AFM image of the as-grown CrS2 sample, blue bar in the image is X axis of (d). (d) AFM height profile of as-grown 1T-CrS2 with average thickness of~1.6nm. (e) STEM image of 1T-CrS2 and shows d-spacing~0.336 nm. (f) Low-magnification TEM image of the device, showing that the transferred CrS2 layer was suspended on the membrane with Au electrodes on both sides. (g,h) In-situ TEM observation of the biasing experiment after 5V biasing for 5 min of 1T-CrS2. Time-sequencing TEM images showing the structural evolution of biasing. The inset shows the corresponding FFT-DP to reveal the variation of crystallinity of the sample. (g) Initial structure of 1T-CrS2. (h) 1T-CrS2 under in-situ biasing experiment after 10 minutes.

Figure 1
(Invited) Laser-Induced Graphene for Improved Electrochemical Biosensors
Authors: Bedewy Mostafa
Published: August 2024

Laser-induced graphene (LIG) has emerged as a promising technique for fabricating porous graphene electrodes for many applications, including biosensors and medical devices. However, improving electrochemical properties of LIG hinges on not only understanding the kinetics and energetics governing the physicochemical process of lasing, but also the tunability of surface chemistry and morphology of the produced LIG. This talk reveals the spatiotemporal laser control for achieving different LIG morphology and atomic structures with demonstrations of seamless transitions between conductive networked LIG structures and insulating fibrous LIG morphologies. The effect of laser fluence and multi-pass lasing on LIG morphology and properties will be shown. In addition, molecular engineering of the polymer substrate is explored for controlling the chemical and physical properties of the produced LIG. Finally, the electrochemical detection of neurotransmitters in the nanomolar range will be demonstrated. Our results show that heteroatom doping of graphene is possible by including sulfur or fluorine atoms into the backbone of the polyimide synthesized by two-step polycondensation. Accordingly, both the surface hydrophobicity and sensing sensitivity are shown to depend on the heteroatom-doping content. Taken together, our work paves the way for scalable fabrication of functional graphene-based electrodes and coatings on polymers for flexible and wearable electronics, as well as implantable devices, such as neural probes.
(Invited) Blue Organic Light-Emitting Diode Using Dynamic Exciton for Low Driving Voltage
Authors: Izawa Seiichiro
Published: August 2024

Among the three primary colors, blue emission in organic light-emitting diodes (OLEDs) are highly important but very difficult to develop. OLEDs have already been commercialized; however, blue OLEDs have the problem of requiring a high applied voltage due to the high-energy of blue emission. Herein, an ultralow voltage turn-on at 1.47 V for blue emission with a peak wavelength at 462 nm (2.68 eV) is demonstrated in an OLED device. This OLED reaches 100 cd/m2, which is equivalent to the luminance of a typical commercial display, at 1.97 V. Blue emission from the OLED is achieved by the selective excitation of the low-energy triplet states at a low applied voltage by using the charge transfer (CT) state as a precursor and the triplet-triplet annihilation, which forms one emissive singlet from two triplet excitons. We found that the essential component for efficient blue emission is a smaller energy difference between the CT state and triplet exciton, accelerating the energy transfer between the two states and achieving the optimal performance by avoiding direct decay from the CT state to the ground state. Our study demonstrates that the developed OLED allows for a much longer operation lifetime than that from a typical blue phosphorescent OLED because the blue emission originates from a stable low-energy triplet exciton that avoids degrading the constituent materials.
(Invited) Two-Dimensional Metal–Organic Framework Acts As a Hydrogen Evolution Cocatalyst for Overall Photocatalytic Water Splitting
Authors: Sakamoto Ryota
Published: August 2024

Water-splitting semiconductor photocatalysts require hydrogen evolution reaction (HER) cocatalysts, the majority of which are robust metals and metal oxides. Metal complexes feature designability and reaction selectivity. This feature should be appreciated in the application as HER cocatalysts by suppressing unfavorable back reactions; however, low stability hampers their application. In this research, we demonstrate that a fully π-conjugated and conductive two-dimensional metal–organic framework (2D MOF), which possesses both virtues of metals/metal oxides and metal complexes, serves as an ideal HER cocatalyst candidate. NiBHT, a kind of 2D MOF, is deposited on the photocatalyst SrTiO3:Al with CoO
x
as an oxygen evolution cocatalyst to show long-term overall one-step water splitting with an apparent quantum efficiency (AQE) of 6.5% at 350 nm. In comparison to Pt as a representative HER cocatalyst, NiBHT turns out to be a suppressor of back reactions related to oxygen reduction reactions, which is proven both experimentally and theoretically.
(Invited) Charge Separation Processes in Non-Fullerene Acceptors Studied by Time-Resolved IR
Authors: Yamakata Akira
Published: August 2024

The mechanism of charge transfer and charge dissociation processes are investigated by femtosecond time-resolved IR absorption spectroscopy.
(Invited) Real-Time Quantum–Classical Simulation as an Observation Tool for Dynamic Exciton Phenomena
Authors: Uratani Hiroki
Published: August 2024

Real-time computational simulations are promising tools for investigating ultrafast and nanoscale dynamical phenomena because of the absence of limitations in spatial and temporal resolutions. In this talk, we will introduce our efficient computational simulation technique for coupled electronic–nuclear dynamics and show how it can provide the microscopic insights into dynamic exciton phenomena such as exciton dissociation at donor–acceptor interfaces.
(Invited) Computational Analysis of the Excited States in the Film States of Non-Fullerene Acceptors
Authors: Higashi Masahiro
Published: August 2024

Non-fullerene acceptors are currently widely used as the acceptors of organic thin film solar cells due to their high efficiency. However, the molecular mechanism is still unclear. We have studied the excited states in the film states of non-fullerene acceptors together with experimental collaborators by using theoretical methods. In this presentation, we will present recent progress of our research. For example, we will talk about the excited states in the film states of ITIC. ITIC is a popular acceptor-donor-acceptor-type non-fullerene acceptor. Recently, our collaborator, Prof. Yamakata at Okayama University, Japan, found that the charge separation can take place in ITIC acceptor film even without donor molecules. We investigated this phenomenon by using MD simulations and quantum chemical calculations. MD simulations of the ITIC film showed that the acceptor parts of ITIC are stacked with each other. The dominant angle between two stacked ITIC was found to be ~180 degrees, making J-type dimer. On the other hand, it was also found that there are quite a few V-type dimers with the angles less than 90 degrees. Quantum chemical calculations revealed that the dipole moment in the excited state of J-type dimer is almost zero whereas that of V-type dimer is quite large, indicating strong charge-transfer excited state. Therefore, it is considered that the charge separation of ITIC film can take place in the V-type dimers. We also investigated the excited states in the film states of ITIC analogs. Recently, our collaborator, Prof. Ie at Osaka University, Japan, synthesized several ITIC analogs with different sidechains and found the different efficiency of solar cells. We theoretically investigated the excited states in the film sates of ITIC analogs as in the case of ITIC. It is found that the modification of side chains can change the distributions of angles between two stacked molecules and excited-state properties. These findings highlight the importance of controlling stacking structures in the film state for the efficiency of organic thin film solar cells.
(Invited) Influence of Vibronic Interaction of Charge Transfer Excitons in PTB7/BTA-Based Nonfullerene Organic Solar Cells
Authors: Muraoka Azusa , Ikeyama Sumire , Minamia Yuzuka
Published: August 2024

For the design of rational D/A interfaces, it is important to elucidate the dynamic processes of excitons generated at the D/A stacking structure interface and the photoelectric conversion mechanism. We predict that the charge-transfer excitons initially formed are weakly bound electron-hole polaron pairs, which dissociate without relaxing to the charge-transfer state and diffuse as free electron polarons and hole polarons. We consider this to be a nonadiabatic process due to oscillatory interactions in the initial charge-transfer excitonic state. In this study, we use time-dependent DFT to investigate the electronic structure, electron-hole distance, electron coupling in charge transfer state generated by photoexcitaion and the Huang- Rhys factors of the D/A complex BTAx, PCTBT/BTAx and PDCBT/BTAx (x = 1, 3)) in the excited state and the exciton-phonon coupling and nonadiabatic process. Based on the above, we aim to elucidate the role of vibronic interactions in CT excitonic states and the control of JSC and electron-hole recombination.
(Invited) Synthesis and Application of Perfluorinated Compounds
Authors: Akiyama Midori
Published: August 2024

The presentation includes

(1) Synthesis and properties of perfluorocubane

(2) Perspectives on perfluorocubane and its derivatives

(3) Application of perfluoroadamantyl groups for materials
Activation/ Deactivation of Surface States of Heterostructure (Anatese-TiO2/Au) Via Addition of Materials with High Band Gap, Rutile TiO2 (R-TiO2) or Low Band Gap Silicon (Si), and Fabrication Strategy
Authors: Gyanprakash Maurya , Sharma Gyan , Behra Dilip Kumar , Upadhyay Arun , Pala Raj Ganesh
Published: August 2024

The addition of high band gap or low band gap material not only modulates the optical absorption cross-section but also affects the surface state reactivity of heterostructure towards the photoelectrochemical (PEC) water splitting. Further, the deposition strategy to assemble the heterostructure also affects the effectiveness of the heterostructure. To explore such issues, we fabricated the two sets of heterostructures containing (A-TiO2, R-TiO2) and (Si, A-TiO2) via the click chemistry approach through two different strategies, i.e., layer-by-layer heterostructure (LLH), and randomly deposited heterostructure. In LLH strategy, only the addition of high band gap material R-TiO2 enhances the reactivity of the surface states. On the other hand, the addition of the low band gap material Silicon (Si) hampers the reactivity of the surface states of the heterostructure deposited via the LLH. Further, by changing the deposition strategy to RDH, the reactivity of surface states diminishes by adding either the high band gap or the low band gap material. These observations were rationalized from the framework of band structure/band-alignment in the heterostructure and also via electrochemical impedance spectroscopy (EIS).

In LLH, the addition of the A-TiO2 quenches electrons from the conduction band (CB) of R-TiO2, and the holes of A-TiO2 are transferred to R-TiO2. The holes from R-TiO2 participate in activating the surface states present at the surface. On the other hand, the addition of silicon to LLH, having CB above the CB of A-TiO2, does not allow the electrons to transfer from A-TiO2 to Si; hence, the CB electrons from A-TiO2 transfer to surface states, which enhances the energy level of surface states, making it more negative than the VB of Si. The negative shift of surface states of A-TiO2 makes it the recombination center. Interestingly, changing the fabrication strategy from LLH to RDH makes the nature of surface states from reactive to recombination states due to the interfacing of all materials with the underlying substrates.

EIS was utilized to measure and analyze the low-frequency capacitance due to the reactive surface state. The low-frequency capacitance of LLH with A-TiO2 shows the maxima at onset potential, confirming the role of reactive surface states. On the contrary, low-frequency capacitance increases monotonically for LLH with Si addition, showing the effect of recombination surface states. Overall, the study provides pointers on the interplay between band positions and electron-hole separation in heterostructures and how they can be effectively used to enhance surface reactivity in PEC water splitting.
(Invited) Realizing the Lowest Bandgap and Exciton Binding Energy in a Two-Dimensional Lead Halide System
Authors: Sarma D. D.
Published: August 2024

3-dimensional hybrid halide perovskites have been intensely researched because of their extraordinary optoelectronic properties with spectacular quantum efficiencies arising primarily from their suitable bandgaps to harvest the solar spectrum, low excitonic binding energies, and low-cost synthetic processes. However, stabilizing these materials under real-life operating conditions has proven to be a challenge, leading to extensive explorations of lower dimensional analogous hybrid halide materials that are often more stable, though generally having considerably higher bandgaps and excitonic binding energies. I shall present some of our investigations leading to the synthesis of a highly moisture-stable 2-dimensional hybrid lead halide material with the lowest bandgap and exciton binding energy within this class of compounds.1 I shall detail the origin of such a low bandgap and exciton binding energy, identifying the most critical control parameters to determine these properties. In addition, I shall also present preliminary results to suggest the beneficial impacts of incorporating the same organic ligand while making a solar photovoltaic device based on three-dimensional hybrid lead halide perovskites.

Reference:

Debasmita Pariari, Sakshi Mehta, Sayak Mandal, Arup Mahata, Titas Pramanik, Sujit Kamilya, Arya Vidhan, Tayur N. Guru Row, Pralay K. Santra, Shaibal K. Sarkar, Filippo De Angelis, Abhishake Mondal, and D. D. Sarma, Realizing the Lowest Bandgap and Exciton Binding Energy in a Two-Dimensional Lead Halide System, J. Am. Chem. Soc. 145, 15896 (2023).
Deciphering the Interplay of Structure and Charge Carrier Dynamics in Reduced-Dimensional Perovskites
Authors: Sun Kun , Zheng Tianle , Guo Renjun , Liu Shangpu , Jiang Xiongzhuo , F. Huber Linus , Liang Yuxin , A. Reus Manuel , Li Zerui , Guan Tianfu , Schwartzkopf Matthias , Deschler Felix , Müller-Buschbaum Peter
Published: August 2024

Reduced-dimensional perovskites (RDPs) have advanced the development of perovskite solar cells (PSCs) due to their tunable energy landscape, structure, and orientation. Thus, we aim for an increase in the understanding of structure-photophysical properties of Dion-Jacobson (DJ) and Ruddlesden-Popper (RP) RDPs with different dimensionalities. Our findings reveal that RP RDPs with lower dimensionality exhibits a dominant n=2 phase, preferential out-of-plane orientation, and longer charge carrier lifetime compared with DJ RDPs, as evidenced by X-ray scattering technique and transient absorption spectroscopy. In addition, we unveil the film growth of respective RDPs by in-situ X-ray scattering, showing the stoichiometry-determined phase growth. The formation of lower-n phases in RP RDPs with higher dimensionality is thermodynamically favored, while those phases are likely in the form of “intermediate phase”, which bridge the 3d-like and lower-n phases in DJ RDPs. DJ RDPs with higher dimensionality demonstrate comparable phase purity, giving rise to more sufficient energy transfer and longer charge carrier lifetime. As such, DJ-based PSCs (n=4) demonstrate better device stability under ISOS-I-L conditions compared to RP-based PSCs. Leveraging these structural and photophysical insights, our work paves the way for dictating the utilization of RDPs in 3D PSCs and the fabrication of quasi-2D solar cells.
Modulating the Electronic Structure of Metal Halide Perovskites for Efficient Selective CO2 Photoreduction to CO
Authors: Wang Chunhua , Zhu Zhi , Liu Biao , Wang Yannan , Ng Yun Hau
Published: August 2024

Metal halide perovskites (MHPs) have recently held great promise for solar-to-fuel conversion via artificial photosynthesis technology. However, the conversion efficiency of most MHP photocatalysts is still far below that necessary for their practical implementation. Modulating the electronic structure is a promising strategy to solve this issue. Here, taking Cs2AgBiBr6 as a prototype, we investigate the interplay between the local electronic structure of Cs2AgBiBr6 and its photocatalytic performance via introducing heteroatoms. Theoretical calculations reveal that Au heteroatom-mediated orbital rehybridization induces high electron densities and tailors the d-band center of Cs2AgBiBr6, endowing more upshifted d-band center and enhanced adsorption strength of intermediates, thereby resulting in decreased energy barriers for selective CO2 photoreduction to CO product. Experimentally, we report the Cu-incorporated Cs2AgBiBr6 catalyst for selective photoreduction of CO2 to CO in a solid-gas system without sacrificial agents, yielding an on average CO generation rate of 47.3 μmol g−1 with approximately 100% selectively, outperforming the pure Cs2AgBiBr6 and comparable to the reported MHP-based photocatalysts. This work showcases modulating the electronic structure of MHP photocatalysts offering a powerful route for effective solar fuel generation.
(Invited) Plasmonic Nanofabrication of Chiral Nanodisk Ensembles
Authors: Tatsuma Tetsu , Ishida Takuya , Kameoka Yuri
Published: August 2024

Chiral plasmonic nanostructures attract attention because those could be applied to enantioselective chemical sensors, optical isolators, light sources for circularly polarized light (CPL), metasurfaces, and metamaterials. In many cases, chiral plasmonic nanostructures are fabricated by a top-down method such as electron beam lithography (EBL). Since EBL is time-consuming and expensive, we have developed photoelectrochemical methods in which a site-selective reaction is driven by optical near field generated around anisotropic metal nanoparticles under right- or left-CPL. As anisotropic metal precursors for preparation of chiral nanoparticles, we have used gold or silver nanocuboids, nanorods, nanocubes, and triangular or hexagonal nanoplates so far.1-5 In the present work we demonstrate that laterally isotopic, circular nanodisks can also be used as precursors for the preparation of chiral nanostructures.

We prepared ensembles of circular gold nanodisks on a glass plate by a nanosphere lithography method. A glass plate was coated with a gold thin film, and an array of polystyrene spheres (500 nm diameter) was prepared on the gold film. The polystyrene spheres were etched by oxygen plasma, and the exposed gold film was etched by argon ion milling. As a result, an ensemble of gold nanodisks (~200 nm diameter) was obtained. Each nanodisk was capped with a polystyrene cone, and the cap was removed by sonication in toluene if necessary. We used both capped and uncapped nanodisk ensembles. The ensemble was irradiated with visible right- or left-CPL in the presence of silver ions and sodium citrate. The obtained Au-Ag nanostructures exhibited circular dichroism (CPL), indicating that the nanostructures have chirality. Initial deposition at arbitrary site may break the geometric symmetry, resulting in the growth into chiral structures.

Saito, K.; Tatsuma, T. Nano Lett.
2018, 18, 3209–3212.

Morisawa, K.; Ishida, T.; Tatsuma, T. ACS Nano
2020, 14, 3603–3609.

Shimomura, K.; Nakane, Y.; Ishida, T.; Tatsuma, T. Appl. Phys. Lett.
2023, 122, 151109.

Homma, T.; Sawada, N.; Ishida, T.; Tatsuma, T. ChemNanoMat
2023, 9, e202300096.

Ishida, T.; Isawa, A.; Kuroki, S.; Kameoka, Y.; Tatsuma, T. Appl. Phys. Lett.
2023, 123, 061111.
(Invited) Energy Transfer in Hybrid Plasmonic-Polymer Nanomaterials
Authors: Landes Christy F.
Published: August 2024

Energy transfer between plasmonic nanoparticles and polymer acceptors is a possible means to overcome fast competing processes such as rethermalization. I will discuss recent work in which we showed that polyaniline (PANI), which readily hybridizes onto gold nanorods (AuNRs), undergoes switchable energy transfer when the PANI chemical structure is modulated between its emeraldine base and salt forms. Energy transfer had not previously been identified as a mechanism in this common hybrid nanomaterial, despite the fact that AUNR/PANI hybrids have been widely studied for refractive index switching. Because energy transfer depends strongly on spectral overlap between the donor (AuNR plasmon) and the acceptor (PANI absorption) spectra, small changes in overlap within a heterogeneously broadened colloidal sample are enough to obscure the effect in ensemble spectroscopy. Single-particle scattering studies exploit the innate heterogeneity of AuNR/PANI samples because we were able to examine the spectral overlap 1 hybrid at a time and show that strong energy transfer can occur when overlap is maximized in either the emeraldine base or salt forms. Thus, the small differences in AuNR/PANI structure turn out to be an advantage when we look one hybrid at a time.
(Invited) Calendar Life Analysis of Si-Containing Anodes for Li-Ion Batteries
Authors: Tomich Anton , Verma Ankit , Gupta Abhay , Rodrigues Marco-Tulio F , Jansen Andrew N. , Abraham Daniel P. , Carroll Gerard Michael , Schulze Maxwell C , Burrell Anthony , Colclasure Andrew M. , Veith Gabriel M. , Dufek Eric J. , Weddle Peter J , Prakash Nina , Harrison Katharine L. , Neale Nathan R. , Vaughey John T. , McBrayer Josey D, , Johnson Christopher S.
Published: August 2024

Because of their high-gravimetric capacities, the use of Si-containing anodes in Li-ion batteries can lead to a large jump in energy densities. However, the calendar life of these Si containing batteries is poor because of the highly reducing chemical reactivity of lithium silicides at high states of charge (SOC) as well as other factors posing challenges for future life estimation and those attempts to extend lifetime. Lithium consumption through loss of inventory to solid electrolyte interphase (SEI) growth (and re-growth), and potential impedance increase through loss of active material contributes greatly to the shortened calendar life; typically on the order of one year to 80% energy retention. The US Department of Energy (DOE) has established a program (the Silicon Consortium Project or SCP) that currently is confronting the basic and applied science problems of Si with the hopes of developing >10 year calendar life for Si-containing cells. In this presentation, I will discuss these issues and provide some solutions to partly solve the short calendar life of Si together with models to estimate the future life.
(Invited) Novel Q Carbon Anodes for Sodium-Ion Batteries
Authors: Paranthaman Mariappan Parans , Pethe Saurabh , Sahoo Siba Sundar , Sun Xiao-Guang , Narayan Jagdish
Published: August 2024

The main goal of this research is to develop low-cost anodes for sodium-ion batteries. Lack of standard carbon intercalation/insertion anode for sodium-ion batteries has greatly hindered its application. Two types of Q carbons have been studied as a potential anode material for sodium-ion batteries. Q1 carbon exhibits a high initial columbic efficiency of 81% but has a low-capacity retention of less than 60%. Whereas Q2 carbon has a low initial columbic efficiency of 58% but has a high-capacity retention of 81%. Q2 exhibited a stable capacity of 168 mAh/g at a cycling rate of C/3 which is comparable to other high performing hard carbon anodes. This work will discuss in detail about the synthesis procedure, microstructural and electrochemical performance of the Q carbons. This study reports the successful pathway of using Q carbon as a promising anode for sodium ion batteries.

ACKNOWLEDGEMENTS

This research was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.
Applications of Porphyrin-Based MOFs in Food Security
Authors: Harvey Piere d. D.
Published: August 2024

Metal-organic frameworks, MOFs, are a very important class of porous materials, many of which being already commercial. Concurrently porphyrin-based MOFs, PMOFs, are one sub-class, but the porphyrin unit provides multiple features rendering them quite special. Indeed, the PMOFs are semi-conducting, deeply colored and strongly fluorescent materials, all at the same time, and can easily be prepared in the nano-sized scale. These features can cleverly be exploited in the field of food security. The various manners by which PMOFs contribute to food security is surveyed and critically described. Detection of toxins and mycotoxins, and preventions against microbes, mainly fungi and bacteria, are the two main current research topics in this area. The development of sensors and biosensor (including aptasensors) is clearly the most flourishing topic as colorimetric, fluorescence, electrochemistry, and electroluminescence techniques have successfully been developed. Prevention is another successful approach. Despite it is quite important, sanitary prevention and correcting techniques have not been fully explored so far. Two strategies have been assessed, 1) antibacterial food packaging and 2) extraction of contaminants, when possible. This presentation surveys the various techniques and applications developed so far in food security hazards using PMOFs.
Copper Corrole Electropolymers
Authors: Paolesse Roberto , Di Zazzo Lorena , Guido Lorenzo , Di Filippo Ilaria , Magna Gabriele , Di Natale Corrado
Published: August 2024

The electrochemical polymerization of the copper complex of 5,10,15-tris-(4-aminophenyl) corrole leads to the formation of conductive films, which have been deposited onto interdigitated electrodes to develop chemoresistive sensors. These devices are of interest because of their facile miniaturization and integration into low-cost electronic circuits. It is interesting to note that the properties of these films, such as morphology, semiconducting nature and sensitivity, can be tuned by modifying the synthetic electropolymerization protocols. This opportunity can allow the preparation of cross-selective sensors that can be integrated into miniaturized conductometric electronic nose platforms.
Biocatalytic Carbenoid N-H Insertions Via Engineered Myoglobins: A Systematic Reaction Mechanism Study
Authors: Khade Rahul , Zhao Xinyi , Wang Carolyn , Zhang Yong
Published: August 2024

Recently engineered myoglobins have demonstrated excellent biocatalytic activities for a broad range of carbenoid N-H insertion reactions with up to >99% yield. Such biocatalysts offer various tuning points beyond protein residues, such as metal center, and axial ligand, to regulate different chemical reactivities. However, there is no computational mechanistic study to reveal its basic reaction mechanism, which could be utilized to study effects of different catalyst component for rational biocatalyst design. The reported computational mechanistic papers of other heme protein catalyzed N-H insertion have limited information without a careful comparison of all possible pathways and just focused on certain steps. Building on our group’s recent mechanistic work on a number of heme carbene transfer reactions, we performed a quantum chemical study to systematically study all possible reaction pathways for myoglobin catalyzed N-H insertions, which starts from the reactants to final released products and thus constitute a complete reaction pathway study. We examined ylide (proton transfer), hydrogen atom transfer, and hydride transfer pathways. In the favored ylide pathways, we calculated the direct proton transfer from amine to carbene and indirect paths with both concerted and stepwise proton transfer and dissociation components. For the indirect pathways in which the proton resides on the carbonyl oxygen of the original carbene substituent, subsequent water-assisted proton transfer from this carbonyl oxygen to carbene’s carbon to form the final product was also investigated. The most favorable pathway from this systematic reaction mechanism study was further supported by new experimental work from our collaborators, the original developer of myoglobin-based biocatalysts. These novel mechanistic results provide important mechanistic information for future biocatalyst design with enhanced reactivities.
Exploration of Synthesis and Coordination Chemistry of Thiazole-Containing Calix[3]Pyrroles
Authors: Shibata Kotaro , Shibata Kotaro , Pati Narendra N. , Inokuma Yasuhide
Published: August 2024

Calix[n]pyrroles have been used as powerful and specific receptors and as extractants for anions and ion pairs over the past 20 years. In the recent past, calix[4]pyrroles have been used as systems that can move ions and ion pairs over lipophilic membranes [1]. Unfortunately, the coordination chemistry of calix[n]pyrroles hardly explored. The ring-contracted analog of calix[n]pyrrole, calix[3]pyrrole, was synthesized and recently published [2]. The structure of calix[3]pyrrole and its analogues is strained, and they show an appealing strain-induced ring expansion response. On the other hand, the synthesis of calix[3]pyrrole requires multistep reactions including cyclization of hexaketone precursor and Paar–Knorr synthesis with the total yield of 4%. Extended use of calix[3]pyrrole analogues necessitates further refinement of the synthesis process.

Here, we demonstrate the synthesis of new calix[3]pyrroles analogue, calix[1]pyrrole[2]thiazole (3). Direct macrocyclization between bis(α-bromoketone) and 2,2-dimethylpropane (bis-thioamide) produced the calix[1]furan[2]thiazole (1), with 60% yield. The furan unit of 1 was converted into pyrrole to give calix[1]pyrrole[2]thiazole 3 (Figure 1).

Single-crystal X-ray analysis revealed a cone-shaped conformation of calix[1]pyrrole[2]thiazole 3, with all three heterocycles pointing in the same direction through strong intramolecular hydrogen bonding. However, unlike calix[3]pyrrole, calix[1]pyrrole[2]thiazole was completely stable under acidic conditions, which may be due to the basic nature of the thiazolimine units.

Metal coordination of calix[1]pyrrole[2]thiazole was attempted and its Zn(II), Ag(I) and Pd(II) complexes were obtained by appropriate metalation procedures. The central metal ion of the Zn(II) complex is coordinated by a conical 3 and an axial ethyl group to behave as a monoanionic tridentate ligand. In contrast, it acts as a bidentate neutral ligand for Pd(II) or Ag(I) complexation. The synthesis of meso-aza calix[1]pyrrole[2]thiazole is in progress.

Figure 1
Elucidating the Hydrogen Evolution Reaction Mechanism of Immobilized Iron Porphyrin Electrocatalysts
Authors: Heppe Nils , Gallenkamp Charlotte , Snitkoff-Sol Rifael Z , Paul Stephen Daniel , Segura Salas Nicole , Potapkin Vasily , Jafari Atefeh , Leupold Olaf , Schuenemann Volker , Elbaz Lior , Krewald Vera , Kramm Ulrike I.
Published: August 2024

Based on global warming our society need to change towards CO2 free or neutral options of energy supply. The hydrogen economy plays an important role in providing and utilizing green hydrogen. While platinum is the best-known catalysts for the hydrogen evolution reaction (HER), alternatives are required that are sustainable and free of platinum group metals (PGMs).

Metal-nitrogen-carbon (MNC) catalysts have shown promising activity for the HER [1], however, often beside catalytically active MN4 centers they contain side phases that hinder mechanistic insights. The inhomogeneity in composition is based on the usual preparation approaches, that involve in minimum one pyrolysis or heat-treatment step. To avoid side phases, we focused on immobilized iron porphyrin model complexes and explored there the HER.

In this work, I will present our results associated with a substituent variation [2] and in-depth characterization by post-mortem and in situ approaches using different nuclear resonance techniques [3]. On the basis of this, we identified different species associated with the reaction cycle and the rate limiting step.

The knowledge on this will help further improvement of the porphyrinic system for HER and validation to what extent a similar mechanism applies after the pyrolysis.

References

[1] A. Shaharei, A. Moradabi, I. Martinaiou et al., Elucidating the origin of hydrogen evolution reaction activity in mono and bimetallic Metal- and Nitrogen-doped Carbon Catalysts (MeNC), ACS Appl. Mater. Interfaces 2017, 9, 25184−25193.

[2] N. Heppe, C. Gallenkamp, S. Paul et al., Substituent effect in iron porphyrin catalysts for the hydrogen evolution reaction, Chem. Europ. J. 2023, 29(19) e202202465.

[3] N. Heppe, C. Gallenkamp, R. Snitkoff-Sol et al., Applying Nuclear Forward Scattering as in situ and operando tool for the characterization of FeN4 moieties in the hydrogen evolution reaction, ChemRxiv, 2023, 10.26434/chemrxiv-2023-sk5sr.
Design, Reactivity, and Active Site of Atomically Dispersed Pt Catalysts for Electrochemical Chlorine Evolution Reaction
Authors: Joo Sang Hoon
Published: August 2024

The electrochemical chlorine evolution reaction (CER) is a key anodic reaction in the chlor−alkali process for Cl2 production, on-site generation of ClO–, and Cl2-mediated electrosynthesis.1−3 For more than a half-century precious metal-based mixed metal oxides (MMOs) have been mainstays as CER catalysts, however, they intrinsically suffer from the selectivity problem arising from a parasitic oxygen evolution reaction (OER). We have recently developed a new CER catalyst based on atomically dispersed Pt sites on a carbon nanotube (Pt1/CNT), which catalyzes the CER with excellent activity and selectivity.4 The Pt1/CNT catalyst shows superior CER activity to a commercial Ru/Ir-based MMO and a Pt nanoparticle-based catalyst. Importantly, Pt1/CNT exhibits very high CER selectivity near 100% even in low Cl− concentrations (0.1 M) and neutral media, under which the OER is favored over the CER. In situ X-ray absorption spectroscopy and density functional theory calculations reveal that the CER over Pt1/CNT augments with the direct adsorption of Cl− ion on Pt, which can break the scaling relationship between CER and OER. The Pt1/CNT catalyst also shows unusual potential-dependent switching behavior of CER kinetics and rate-determining step.5 Pt1/CNT shows a reaction order of ~1.8 in the low overpotential regime, where the Volmer step is the rate-determining step (RDS). Interestingly, in the high overpotential region, the CER over Pt1/CNT proceeds with a lower reaction order and the RDS switches to the Heyrovský step. We also show that the Pt1/CNT catalyst is comprised of multiple Pt sites with different coordination environments and identify a genuine active site in Pt1/CNT catalysts for the CER.6

K. B. Karlsson and A. Cornell, Selectivity between Oxygen and Chlorine Evolution in the Chlor-Alkali and Chlorate Processes. Chem. Rev.
116, 2982–3028 (2016).

S. Exner, T. Lim, and S. H. Joo, Circumventing the OCl vs. OOH Scaling Relation in the Chlorine Evolution Reaction: Beyond Dimensionally Stable Anodes. Curr. Opin. Electrochem.
34, 100979 (2022).

Trasatti, Electrocatalysis: Understanding the Success of DSA. Electrochim. Acta
45, 2377–2385 (2000).

Lim, G. Y. Jung, J. H. Kim, S. O. Park, J. Park, Y.-T. Kim, S. J. Kang, H. Y. Jeong, S. K. Kwak, and S. H. Joo, Atomically Dispersed Pt−N4 Sites as Efficient and Selective Electrocatalysts for the Chlorine Evolution Reaction, Nat. Commun.
11, 412 (2020).

Lim, J. H. Kim, J. Kim, D. S. Baek, T. J. Shin, H. Y. Jeong, K.-S. Lee, K. S. Exner, and S. H. Joo, General Efficacy of Atomically Dispersed Pt Catalysts for the Chlorine Evolution Reaction: Potential-Dependent Switching of the Kinetics and Mechanism, ACS Catal.
11, 12232−12246 (2021).

Cho, T. Lim, H. Kim, L. Meng, J. Kim, J. H. Lee, G. Y. Jung, F. Viñes, F. Illas, K. S. Exner, S. H. Joo, and C. H. Choi, Importance of Broken Geometric Symmetry of Single-Atom Pt Sites for Efficient Electrocatalysis, Nat. Commun.
14, 3233 (2023).
Molecular Materials Based on Subphthalocyanines
Authors: Torres Tomas , Labella Jorge , Laforga Juan B. , Agramunt Adriana , Holgado Daniel , Azizi Kobra , Garcia-Calvo Jose , Boughanmi Habiba
Published: August 2024

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
The Diverse Electrochemistry and Photophysics of Pyrrolopyrroles
Authors: Vullev Valentine I. , Gryko Daniel T. , O`Mari Jaime O. , Vakuliuk Olena
Published: August 2024

Pyrrole is among the most popular molecular scaffolds for biology. Tetrapyrroles, such as porphyrins, corrins and their derivatives, are the quintessential redox centers and chromophores exhibiting a wide range of electrochemical and optical characteristics. Similarly, pyrrolopyrroles, built on condensed five-member rings with nitrogens as heteroatoms, offer scaffolds for organic chromophores with diversity of redox and photophysical properties. For example, pyrrolo[3,2-b]pyrroles are stable electron-rich UV absorbers with quadrupole symmetry (Acc. Chem. Res.
2017, 50, 2334-2345). They can act as immensely potent electron donors and attaching electron-accepting moieties to them leads to the emergence of a myriad of optical phenomena, such as excited-state symmetry breaking (Commun. Chem.
2020, 3, 190) and generating white fluorescence by tuning donor-acceptor electronic coupling (Chem. Sci.
2023). Attaching carbonyls to the pyrrolopyrrole rings drastically changes their electronic properties, making them pronouncedly electron deficient and shifting their absorption to the visible spectral region. For example, 2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-diones, or diketopyrrolopyrroles (DPPs) for short, are excellent electron acceptors and photooxidants (Adv. Opt. Matter.
2015, 3, 2018-320). Their reduction potentials are susceptible to localized electric fields, which has allowed demonstrating dipole-induced rectification of photoinduced hole transfer (Angew. Chem. Int. Ed.
2018, 57, 12365-12369). This field susceptibility extends to the optical properties of DPPs, providing an extra dimension in their utility for photonics and optoelectronics. DPPs, and pyrrolopyrroles in general, are built on small bicyclic scaffolds, i.e., considerably smaller than those of other multi-pyrrole chromophores. The small size enhances the susceptibility of their redox properties to solvation and makes them attractive photoprobes. Therefore, this class of compounds have become indispensable agents for electrochemical and photonic science and engineering.
Charged Porphyrins That Form Electronically Functional Ion Pairs and Assemblies Via
I
π–
I
π Interactions
Authors: Maeda Hiromitsu
Published: August 2024

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 positively and negatively charged species in the assemblies.[1–3] In fact, π-electronic ion pairs comprising porphyrin-based π-electronic anions 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] Among various combinations of the porphyrin anions with porphyrin–AuIIIcomplexes as π-electronic cations,[5] the “activated” ion pair of meso-EWG (electron-withdrawing group)-substituted cation and meso-EDG (electron-donating group)-substituted anion exhibited the electron transfer in the ground state, resulting in the production of the heterodiradical in a close stacking structure as revealed by the ESR.[6] Further modifications of charged porphyrins and analogs have been examined for the electronic properties that are derived from ion pairing.

[1] Recent reviews: (a) Haketa, Y.; Yamasumi, K. et al. Chem. Soc. Rev.
2023, 52, 7170; (b) Haketa, Y. et al. Responsive Mater.
2023, 1, e20230018. [2] Recent reports on ion pairs and assemblies: (a) Yamasumi, K. et al. Angew. Chem. Int. Ed.
2023, 62, e202216013; (b)Sugiura, S. et al. J. Am. Chem. Soc.
2023, 144, 8122; (c) Haketa, Y. et al. Chem. Sci.
2024, 15, in press (DOI: 10.1039/d3sc04564a). [3] Selected reports on pyrrole-based π-electronic molecules: (a) Haketa, Y. et al. J. Am. Chem. Soc.
2020, 142, 16420; (b) Ishikawa, S. et al. under revision. [4] Sasano, Y.; Tanaka, H. et al. Chem. Sci.
2021, 12, 9645. [5](a) Haketa, Y. et al. iScience
2019, 14, 241; (b) Nakajima, R. et al. to be submitted; (c) Maruyama, Y. et al. to be submitted. [6](a) Tanaka, H. et al. J. Am. Chem. Soc.
2022, 144, 21710; (b) Tanaka, H. et al. Chem. Eur. J.
2023, 29, e202203957.