bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Theoretical Study on the Environmental Effects on Photoexcited Properties of Donor-Acceptor-Linked Molecules
Authors: Higashi Masahiro
Published: September 2023

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 molecular dynamics (MD) simulation. In particular, we have focused on the environmental effects on photoexcited properties. In this presentation, we will present recent progress of our research. For example, we will talk about theoretical analysis of 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 acceptor-donor-acceptor type non-fullerene acceptor molecule, ITIC, which has a shorter lifetime in the film state than in solution. 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. First, it is found that the excited-state potential energy surface of TACIC monomer is similar to that of ITIC monomer, which is consistent with the experimental result that both have similar lifetimes in solution. Next, the packing structure of TACIC in the film state is much different from that of ITIC. Analysis of the excited states of dimer obtained from the film state structure demonstrated that the transition dipole of TACIC dimer is much smaller than that of ITIC dimer. These results could be related to the difference in lifetime of the excited state between TACIC and ITIC in the film state. Further analysis is currently in progress. We will also talk about the photoexcited properties of porphyrin-fullerene linked molecules.
In-Situ Charge Carrier Dynamics of Au-Decorated TiO2 Nanorods Toward Photoelectrochemical Water Oxidation
Authors: Chang Yu Peng
Published: September 2023

TiO2 nanorod arrays have been widely used as photoanodes for conducting photoelectrochemical water splitting. Upon decoration with Au, the charge carrier separation of TiO2 can be improved to enhance the water oxidation efficiency. In addition, the plasmonic effect of Au can promote additional charge carrier generation for TiO2, increasing the photoelectrochemical efficiency as well. Interfacial charge dynamics play an important role in governing the photoelectrochemical efficiency of photoelectrodes. In particular, employing in-situ spectroscopic techniques to monitor charge dynamics of photoelectrodes under operation conditions is essential for realizing the veritable working mechanism. In this study, in-situ transient absorption spectroscopy is utilized to monitor the interfacial charge dynamics of Au-decorated TiO2 nanorods under photoelectrochemical operation conditions. The effect of applied bias on the charge carrier dynamics of Au-decorated TiO2 has been elucidated. In specific, the hole dynamics at the photoanode surface has been elucidated to establish the correlation with the photoelectrochemical performance.
Cu-Doped InP/ZnS Core/Shell Quantum Dots:Charge Carrier Dynamics and Solar Hydrogen Production
Authors: Shih Jen An , Hsu Yung-Jung
Published: September 2023

Photocatalytic hydrogen production is a clean and sustainable method to convert solar energy into chemical fuel. Among the different structural types of photocatalysts, colloidal quantum dots (QDs) with narrow bandgap and tunable band structure have demonstrated particularly effective utility in solar hydrogen production. In the present study, InP/ZnS core/shell QDs were prepared and employed as photocatalyst backbone for hydrogen production. By introducing Cu dopants into the ZnS shell of InP/ZnS, the interfacial charge dynamics between InP and ZnS can be manipulated to achieve an activity optimization for solar hydrogen production. Time-resolved photoluminescence spectroscopy was utilized to study the quantitative effect of Cu dopants on the interfacial charge dynamics of the samples. This work provides a fresh hint to manipulate the charge transfer dynamics of QDs by means of dopant introduction towards highly efficient solar hydrogen production.
Colloidal Synthesis and Photoluminescence Property of Near-IR-Responsive Ag8GeS6 Quantum Dots
Authors: Rismaningsih Nurmanita , Kubo Junya , Fujihira Norikazu , Kameyama Tatsuya , Torimoto Tsukasa
Published: September 2023

Semiconductor nanocrystals of a few nanometers in size, called quantum dots (QDs), exhibit unique photochemical properties due to quantum size effect. In recent years, high-quality near-infrared responsive QDs such as CdTe and PbS have been used for wide-ranged applications from light-energy conversions to biomedical applications. However, the contents of highly toxic elements, Cd and Pb, restrict their practical use. On the other hand, group IV-based multinary compound semiconductors, such as Ag2ZnSnS4, Ag8SnS6, and Ag8GeS6, have attracted much attention because of their less toxicity and light absorption property in visible and near-IR region. However, there are only a few reports to prepare size-quantized nanocrystals for tuning their photoelectrochemical properties. In this study, we report the preparation of Ag8GeS6 core and Ag8GeS6@ZnS core/shell QDs using a feasible liquid-phase chemical synthesis method.

As a moisture and air stable Ge precursor, Ge(gly)2(H2O)2 was prepared by the literature method with slight modification[1]. Precursor powders of Ge(gly)2(H2O)2, silver(I) diethyldithiocarbamate, and thiourea were dispersed in a mixture solvent of 1-dodecanethiol and oleylamine, followed by the heat treatment at 423 K for 20 min. Thus-obtained QDs were isolated from the reaction solution by the addition of methanol and ethanol as a non-solvent. Then, the obtained QDs were finally dispersed in chloroform. The obtained Ag8GeS6 QDs were further surface-coated with thin ZnS layer to form Ag8GeS6@ZnS core/shell QDs.

The onset wavelengths in the absorption spectra of Ag8GeS6 and Ag8GeS6@ZnS were observed at 850 nm and 830 nm, respectively. The XRD analysis showed that the obtained nanocrystals had an orthorhombic Ag8GeS6 crystal structure. TEM measurements revealed that the prepared Ag8GeS6 QDs had an average particle size of 4.53 nm while that of Ag8GeS6@ZnS was 5.80 nm. From the difference between the sizes before and after ZnS coating, we estimated the ZnS shell thickness of Ag8GeS6@ZnS to 0.63 nm. The energy gap of Ag8GeS6 QDs was slightly decreased from 1.45 eV to 1.37 eV with an increase in Ge/(Ge+Ag) ratio. Ag8GeS6 QDs with Ge/(Ge+Ag) = 0.8 exhibited a broad photoluminescence (PL) peak at 850 nm with PLQY of about 25%. The surface coating with ZnS remarkably increased the PLQY to 65%, which was considerably high in comparison to those of near-IR-emissive multinary QDs in our previous papers such as Ag–In–Ga–Se and Ag–In–Ga–S–Se QDs [2,3]. Thus, the present Ag8GeS6@ZnS QDs seem to be a promising probe for bio-imaging with near-IR photoluminescence.

[1] A.S.R. Chesman, et al., Chem. Mater, 26, 5726 (2014).

[2] T. Kameyama, et al., ACS Appl. Nano Mater, 3, 3275-3287 (2020).

[3] N. Rismaningsih, et al., J. Mater. Chem. C, 9, 12791-12801 (2021).
Machine-Learning Assisted Identification of Battery Life Models
Authors: Gasper Paul , Collath Nils , Hesse Holger , Jossen Andreas , Smith Kandler
Published: September 2023

Predictive battery life models are commonly utilized to extrapolate degradation trends observed during accelerated aging tests for simulation of degradation in real-world applications. Thus, fitting accelerated aging data as accurately as possible and with low uncertainty is crucial for making believable projections of battery lifetime, but it is challenging to identify algebraic expressions that accurately fit multivariate degradation trends. A review of models published in literature reveal some common expressions for fitting calendar aging data, which is only dependent on temperature and state-of-charge, but no consistency across many models for fitting cycle aging data, indicating the need for a statistically rigorous data driven approach for developing empirical models.

This talk will describe a machine-learning assisted method for identification of predictive battery life models utilizing bilevel optimization and symbolic regression. Bilevel optimization with cross-validation is used to statistically determine cell- and stress-dependent model parameters, while symbolic regression identifies both linear and multiplicative candidate expressions to predict stress-dependent degradation rates by selecting low-order subsets of features from a generated feature library. Because model expressions are identified empirically, it is crucial to ensure resulting models behave according to physical expectations, so the stability of models for interpolation or extrapolation is interrogated qualitatively through simulation and quantitatively through cross-validation and uncertainty quantification via bootstrap resampling. This model identification approach substantially improves upon models identified purely using expert judgement in terms of both accuracy and uncertainty.

Model simulation and validation is then conducted by deriving a state-equation form of the predictive model, enabling simulation of battery aging under dynamic stresses. This enables validation of the predictive battery model on lab-based tests with varying conditions or on drive-cycle or application-cycle testing protocols. Parameter uncertainty can be carried forward into model simulation, giving lifetime estimates and confidence windows for cell- or system-level lifetime. The financial impact of battery model uncertainty can be estimated by incorporating uncertainty into a technoeconomic model.
Metallic Organic Framework (MOF) Applications in Novel Lithium-Sulfur Batteries
Authors: Smolinski Maciej , Ossowska Aleksandra , Szczęsna-Chrzan Anna , Łaszcz Adam , Marczewski Maciej , Marcinek Marek
Published: September 2023

Today lithium-ion batteries are the basis of portable energy source. Wildly used in electronic devices and electric vehicles lithium-ion type of batteries became a standard. Despite good electrochemical performance and their universality, fast development of the market for efficient power sources makes them unable to meet this challenge. As a promising competitor or even a successor of lithium-ion batteries often named are lithium-sulfur batteries. It’s mostly because of their high specific capacity (1675 mAh g-1) and relatively big deposit of sulfur on Earth. The main reason, why this type of batteries is not commercialized yet is the problem with the application and stability of the sulfur electrode. The expansion of the sulfur when charging, its insulation and dissolution in organic solvents from the electrolyte, resulting the creation of polysulfides chains, are the remaining problems to solve before lithium-sulfur batteries could be spread in the commerce devices. To solve these issues many additives and compounds have been examined. One of the idea is to use metal-organic frameworks (MOFs) as a sulfur host on the electrode. Because of the porosity of the structure of these materials they are able to “hold” sulfur inside them. Not only it improves the electronic conductivity but also can be a solution to reduce the electrode expansion and sulfur reactions with electrolyte. This report presents a few methods of the possible ways of doping MOFs with sulfur and electrode slurry preparation. All the research was made in cooperation of Warsaw University of Technology from Poland and NTNU and SINTEF from Norway in M-ERA.NET 2 MOGLiS project.
Conductive Metal Organic Framework as Trapping Cathode Additive for High Performance Lithium-Sulfur Batteries
Authors: Nazir Aqsa , Motevalian Saeme , El-Zahab Bilal
Published: September 2023

Lithium-Sulfur (Li-S) batteries with high capacity and energy density have arisen as one of the most promising secondary batteries. However, higher order lithium polysulfide (LiPSs) shuttling and insulating nature of sulfur cathode results in capacity degradation and premature failure of the cell [1]. Here for the first time, we have implemented conductive Cu metal-based Metal organic framework (Cu-MOF) as a Li-S battery cathode material. Cu-MOF cathode catalyst not only reduce the LiPSs shuttle effect but also increase the conductivity of Li-S battery cathode [2].

Here, Cu-MOF pore morphology will trap the polysulfides and further prevent LiPSs shuttling. In addition, the well-defined architecture of organic ligands of Cu-MOF also participate to explicate the involved surface-binding mechanisms of S and polysulfide products. Furthermore, Cu-MOF improve the diffusion rate of Li ions, shackling LiPSs, upsurging conduction of electrons/ions, and regulating the deposition of Li2S2/Li2S towards cathode side [3]. Furthermore, sulfur active material is well percolated inside the pores of conductive Cu-MOF which shows the long-cycling performance as shown in Figure 1.

Benefiting from the unique fibrous, porous, interwoven structure, the conductive MOF@S-composite cathode demonstrates a high initial capacity of 1671 mAh g–1 at 0.05 C rate with a good coulombic efficiency of >95% and the outstanding capacity of 849 mAh g-1 cycles even after 200 cycles at the 0.5 C-rate with coulombic efficiency of 98.3%. It is believed that, the experimental findings and mechanistic understanding of Cu-MOF cathode in this work will open a new avenue for the further development of other conductive MOFs in the Li-S batteries.

Figure 1: Cycling performance of S@Cu-MOF composite at 0.5 C-rate.

References

Mingyue Wang, Zhongchao Bai, Ting Yang, Chuanhao Nie, Xun Xu, Yunxiao Wang, Jian Yang, Shixue Dou, and Nana Wan."Advances in High Sulfur Loading Cathodes for Practical Lithium-Sulfur Batteries." Energy Mater, no.12 (2022): 2201585.

Dan Luo, Chaojie Li, Yongguang Zhang, Qianyi Ma, Chuyin Ma, Yihang Nie, Matthew Li, Xuefei Weng, Rong Huang, Yan Zhao, Lingling Shui, Xin Wang, Zhongwei Chen. "Design of Quasi-MOF Nanospheres as a Dynamic Electrocatalyst toward Accelerated Sulfur Reduction Reaction for High-Performance Lithium–Sulfur Batteries." Mater, no.34 (2022): 210554.

Jun Zhang, Ye Shi, Yu Ding, Lele Peng, Wenkui Zhang, Guihua Yu. "A Conductive Molecular Framework Derived Li2S/N,P-Codoped Carbon Cathode for Advanced Lithium–Sulfur Batteries." Energy Mater, no.7 (2017): 1602876.

Figure 1
Pristine SWCNT Based Cathode Materials for Solid-State Li-Sulfur Batteries
Authors: Kuznetsov Oleg A , Harutyunyan Avetik R.
Published: September 2023

Lithium-Sulfur is a long-studied, but yet to be practically implemented battery chemistry which carries a promise of creating high energy density batteries. It uses cheap and abundant materials, but faces major technological challenges. One of the key challenges is that sulfur as the cathode material has negligible electronic conductivity (5x10-28 S/m), preventing electron exchange in the cathode during battery charge/discharge cycling. The other challenge is the significant (up to 80%) volume changes of sulfur during battery cycling that leads to cracking, delamination, voids formation and loss of electrical contacts, therefore limiting battery durability. To overcome these problems, we have developed a solution-free technology of manufacturing composite self-standing electrodes by in-situ mixing of the aerosolized phases and co-deposition [1]. The electrodes consist of sulfur and catholyte particles imbedded in a 3D network of as grown, pristine single-walled carbon nanotubes. The electrodes are flexible and do not include current collector metal foils or binders. They can be produced up to 1 mm thick, up to 200 mgsulfur/cm2 loading, or 330 mAh/cm2 capacity without the loss of the SWCNT network 3D structure. The macroscopic electrical conductivity of the material increases 30 orders of magnitude compared to that of sulfur, and reaches 102-104 S/m, depending on the SWCNT concentration. The presence of SWCNT network not only solves the electrical conductivity challenge but also durability issue, since flexible/stretchable SWCNT network accommodates the volume change of the sulfur active particles without disruption of the cathode integrity. The electrodes fabricated by this method are being studied as perspective cathodes for solid-state LiS batteries.

A. Kuznetsov, S. Mohanty, E. Pigos, G. Chen, W. Cai, A.R. Harutyunyan, High energy density flexible and ecofriendly lithium-ion smart battery. Energy Storage Materials, 2023 (54) 266-275, ISSN 2405-8297, doi.org/10.1016/j.ensm.2022.10.023
Study of Alternative Binders for Battery Electrode in Aqueous System
Authors: Sepp Silver
Published: September 2023

Materials used to prepare energy storage devices need to be affordable, durable, and safe for environment. PVDF, which is the most popular polymer used as a binder in battery electrodes, requires the use of and toxic solvents for processing, such as N-methyl-pyrrolidone (NMP).1 Water insoluble organic polymers could replace PVDF as the binder in aqueous batteries or redox flow batteries with solid boosters.2 For example, ethyl cellulose is a biodegradable and water-insoluble polymer. Ethyl cellulose-based slurry can be prepared using ethanol as solvent, which makes the process cheaper and more sustainable. Also cross-linked gluten could be used as a binder. In that case water-based slurry could be used to prepare the electrode. Replacing PVDF with more environmentally friendly binder would be beneficial in many ways. It would shorten the assembly procedure due to high speed of solvent evaporation, there are no strict requirements for humidity control and the recycling procedure is easier as there are no fluorinated compounds.3 Therefore, this replacement would enable to produce safer and cheaper energy storage devices.

In this work positive electrodes with different composition have been described using galvanostatic charging-discharging and cyclic voltammetry. Various cell setups have been tested. LiMn2O4 (LMO) has been used as active material for cathode and carbon black Super P as conductive additive. PDVF has been compared with various organic biodegradable polymers as the binder. Using ethyl cellulose as a binder, discharge capacity 100 mAhg−1 was achieved at 0.2C rate for LMO cathode which is comparable to the results obtained with PVDF as a binder. 500 cycles at the rate of 1C showed somewhat better capacity retention for electrodes prepared using PVDF. Also rotating disk electrode experiments were conducted to study the effect of binder to the kinetics of the reaction. The results show that some biodegradable and cheaper binders could be promising option to replace PVDF as binder in aqueous systems. This is highly important in aqueous redox flow battery with solid boosters, where large amount of solid charge storage material is used in tanks to increase the capacity of the system.2

Acknowledgements:

The research was supported by the Estonian Research Council grant MOBTP1023, Archimedes Foundation project SLTKT16432T and by the EU through the European Regional Development Fund under project TK141 (2014–2020.4.01.15–0011).

References:

I. Doberdò, N. Löffler, N. Laszczynski, D. Cericola, N. Penazzi, S. Bodoardo, G. T. Kim, and S. Passerini, J. Power Sources, 248, 1000–1006 (2014).

M. Moghaddam, S. Sepp, C. Wiberg, A. Bertei, A. Rucci, and P. Peljo, (2021) Molecules, 26 (8), 2111 (2021).

L. Ibing, T. Gallasch, P. Schneider, P. Niehoff, A. Hintennach, M. Winter, and F. M. Schappacher, J. Power Sources, 423, 183–191 (2019).
Evolution of the Dynamic Solid Electrolyte Interphase for Halogen-Containing Vs Non-Halogen Mg Electrolytes
Authors: Fan Shengqi , Cora Saida , Sa Niya
Published: September 2023

High-performance electrolytes play a pivotal role in the development of Mg batteries. Grignard-type electrolytes were considered a potential electrolyte for commercial application in Mg batteries. However, due to the limited number of high-voltage cathodes and the corrosion of the battery’s components, non-halogen Mg-based electrolytes have received considerable attention recently. Although some studies reported film formation and passivation at the Mg electrolyte/electrode interface, there is a lack of in-depth analysis of the interfacial evolution for multivalent battery systems, which governs the performance and longevity of the Mg battery. In this study, our aims are to investigate the evolutionary process of the solid electrolyte interphase (SEI) at the Mg interface and to compare reaction mechanisms for halogen-containing versus non-halogen Mg electrolytes. The work presented here offers an in-depth qualitative and quantitative analysis of the SEI evolution.
Understanding Solvation Structures of Localized High-Concentration Electrolytes Used for Li-Metal Batteries
Authors: Efaw Corey M. , Wu Qisheng , Gao Ningshengjie , Zhu Haoyu , Gering Kevin L. , Hurley Michael , Xiong Claire , Dufek Eric J. , Qi Yue , Li Bin
Published: September 2023

Liquid electrolytes in batteries are typically treated as macroscopically homogeneous ionic transport media, despite having complex chemical composition and atomistic solvation structures, thus leaving a knowledge gap of microstructural characteristics. A promising electrolyte system design has recently been developed with the title of a localized high-concentration electrolyte (LHCE). These electrolytes are a summation of three components – a charge-carrying salt, a solvent that solvates the salt, and a diluent that is highly immiscible with the salt. This creates the perception of a high-concentration electrolyte (HCE) with high anion-cation interactions that supports a salt-derived, stable solid-electrolyte interphase, while an LHCE improves bulk electrolyte properties, such as ionic conductivity and viscosity, when compared to an HCE. Much trial by error design of this LHCE concept has been supported by simulations to confirm ionic interactions, cycling data to confirm cell stability, and post-mortem analysis to provide evidence of mechanisms. However, a systematic design to extend the capabilities of LHCEs is still to be desired. Here, we analyzed a specific LHCE mixture with the use of a ternary phase diagram to dictate the best viable mixture to extend the localization of solvation structures while maintaining viable cell-level capabilities. It was seen that the electrolyte mixture has complex mechanisms from individual ion solvation up to the solution network scale, both of which are dictated by the interactions between the three electrolyte components. With the support of both experimental and computational analysis of different electrolyte features, we have begun a methodology of formulating the most ideal LHCE mixtures for improving the cyclability of high-capacity battery chemistries.
Supercapacitors with Gold Colloids That Are Placed at a Short Distance from Active-Carbon Electrodes; The Case for a Plasmonic Effect at the Electrolyte/Electrode Interface
Authors: Grebel Haim , Yu Shupei , Zhang Yuanwei
Published: September 2023

Supercapacitors (S-C) are fast charge/discharge elements. These short-term energy storage found many applications; among which are, powering electronic devices, boosters of fast charging batteries and possibly, as buffers between highly fluctuating sustainable sources and the rather stable electrical grid. For double-layer S-C, one takes advantage of the very narrow interface between an electrolyte and a conductive porous electrode. In contrast, ordinary capacitors are made of a relatively thicker dielectric material, sandwiched between two electrodes.

In the past, polarity increase in capacitors was achieved by dispersing conductive colloids in the entire volume of the dielectric material. This approach was primarily used for microwave and optical devices – a field known as plasmonics. For S-C it means that the conductive colloids should be dispersed within the double-layer region, or fairly close to it. The impact of such an approach on the low frequency supercapacitors is not fully yet known. In order to maintain a full polarization effect (as opposed to simply increasing the electrode conductivity), we kept the AuNP at a short distance from the electrode. This is achieved by coating the colloids with a negatively charged ligand - the same approach used to keep a colloidal suspension intact.

Here we explore the addition of nano-size Au particles (AuNP) to active-carbon electrodes to find a large amplification in the specific capacitance. For example, C-V data at a scan rate of 20 mV/s indicated a specific capacitance amplification of more than 10 (!) (with respect to a reference sample without the colloids) when 30 micro-g of AuNPs were incorporated with 200 milli-g of active carbon while using a 1 M Na2SO4 electrolyte and a 5% cellulose acetate butyrate binder. These experiments were corroborated by simulations: the Au colloids are indeed to be placed at close proximity but not in contact with the electrodes.
The Influence of Additives on the Polybenzimidazole Membranes in Vanadium Redox Flow Batteries
Authors: Diaz-Abad Sergio , Jesse Kate Ashley , Davis Benjamin L , Maurya Sandip
Published: September 2023

In recent years, membrane development has been a focus to replace Nafion as the only viable choice for Vanadium redox flow batteries (VRFBs). Efforts were made to develop polymeric membranes with a lower cost and especially with lower vanadium ions crossover to minimize the costs and hassles associated with frequent electrolyte rebalancing. Among researched VRFB membranes, polybenzimidazole (PBI) membrane stands out as one of the most promising candidates thanks to its incredibly low vanadium permeability and lower cost than Nafion. However, its lower ionic conductivity when compared to Nafion which results in low voltage and energy efficiency – is a main barrier for its widespread acceptance in VRFBs.

In order to improve the conductivity of PBI membranes, efforts have been made, such as chemical alteration of PBI backbone, and addition of ionic and non-ionic side groups. However, these approaches add complexity in the synthetic procedure resulting in a higher membrane cost. Therefore, simple approaches such as blending PBI polymer with additives (e.g. Nafion, polypentafluorostyrene, etc.) provide composite membranes with suitable conductivities for VRFBs. However, these additives leach into the vanadium electrolyte solution depending on their solubility. They can affect the kinetics of the anode and cathode reactions which is largely omitted in the literature. Therefore, in this study, we have investigated the effects of different additives, used for the fabrication of composite PBI membranes, on the electrode and VRFB performance. The kinetic performance loss is studied in-situ and ex-situ by electrochemical impedance spectroscopy. We have also established the Structure–Performance Relationship of additives with VRFB performance.
Pemion®, a High-Performance Hydrocarbon Proton-Exchange Membrane Demonstrating >100 °C Stability for Next-Generation Heavy Duty Fuel Cell Systems
Authors: Britton Benjamin , Jones Scot , Chen Nathan , Adamski Mike , Lee Hsu-Feng , Skalski Thomas
Published: September 2023

Until recently it was thought that hydrocarbon-based (i.e. non-fluorinated) proton-exchange membranes faced intractable issues in achieving the high performances, chemical stability, and mechanical integrity for effective integration into fuel cells. However, Pemion® PF1-HLF8-15-X, a composite membrane incorporating a new class of polyarylene sulfonic acids, has been commercialized to meet and exceed precedents set for decades by perfluorosulfonic acids (PFSAs) membranes. These attributes include:

The first demonstrable success in all three categories of US Department of Energy accelerated stress tests (open circuit, humidity cycling, combined oxidative-mechanical cycling) without additives, using mass-market components and processes.

This suggests greater system lifetimes are achievable and readily incorporated by fuel cell OEMs.

Consistent high performances that exceed heavy duty targets (e.g. peak power densities >1.4 W/cm² with a 15 µm membrane) exhibiting comparable area resistances to state-of-the-art PFSA-based materials but across a broader operational temperature range, including a higher temperature operating window of 95 °C without area resistance gain and 110 °C without degradation,

This enables long-targeted benefits, chief among which are heat exchanger size reductions and an end to over-specification for heavy duty transportation and aviation applications.

Significantly reduced gas crossover in all conditions

This enables greater fuel efficiency and the potential for increased component lifetimes or operational pressures.

A green and “future proof” chemistry

In light of EU-REACH and EPA threat of regulation and the fact that PFSAs emit fluorinated acid derivative PFAS of concern during operation, hydrocarbon materials are the only way to ensure a robust supply chain into the future, with additional benefits of simplifying recycling at end-of-life.

These combined benefits represent the near-term potential to realize a step-function alteration in the economic viability of fuel cell systems for both transportation and stationary applications.
High Capacity Sn Metal Anode for Aqueous Proton-Based Batteries
Authors: Zhang Haozhe , Lu Xihong , Meng Shirley
Published: September 2023

Aqueous proton-based batteries (APBs) as a good choice to respond battery diversity, delivering safety, cost, environmental friendliness and high-power necessary for renewable energy storage.1 However, most promising conventional aqueous battery anodes have relatively poor compatibility in acid. The limited existing anode options like Pb and MoO3 can hardly match the high-performance of advanced cathodes, leading low-voltage and unsatisfactory energy density of APBs.2-4 Therefore, the exploration of high-performance anode materials is thus of critical issue for the APB assembling.

Sn metal should be one of the most suitable APB anode choices due to its relatively high hydrogen evolution reaction (HER) overpotential, large theoretical capacity (451.6 mAh g−1) and negative redox potential (−0.14 V vs. SHE). With a body-centered tetragonal crystal structure and similar facet surface energy, Sn metal deposit in polyhedral morphology isotropically. This may cause serious “dead Sn” issue when deposition capacity increases because large Sn particle has limited contact with the substrate and easily to shed from the electrode, resulting in low Coulombic efficiency and short lifespan.

We will present our efforts of developing Sn anode with high capacity and long lifespan by an interfacial alloying regulation approach. Smaller grain size and more uniform Sn deposition can be achieved by higher propensity for nucleation and Sn migration energy barrier. Extra interfacial interaction suppresses shedding of Sn polyhedron particles, thus prohibiting the formation of “dead” Sn. Based on the optimized Sn metal anode, we propose several promising designs for APBs, with high performance such as high output voltages, good specific energy densities, fast kinetics, and long life.

References

X. Wu, J. J. Hong, W. Shin, L. Ma, T. Liu, X. Bi, Y. Yuan, Y. Qi, T. W. Surta, W. Huang, J. Neuefeind, T. Wu, P. A. Greaney, J. Lu, X. Ji. Nat. Energy
2019, 4, 123-130.

W. Chen, G. Li, A. Pei, Y. Li, L. Liao, H. Wang, J. Wan, Z. Liang, G. Chen, H. Zhang, J. Wang, Y. Cui. Nat. Energy
2018, 3, 428-435.

Y. Liang, Y. Jing, S. Gheytani, K. Y. Lee, P. Liu, A. Facchetti, Y. Yao. Nat. Mater.
2017, 16, 841-848.

X. Wang, Y. Xie, K. Tang, C. Wang, C. Yan. Angew. Chem. Int. Ed.
2018, 57, 11569-11573.
Push-Pull Charge Transfer and High-Potentials Induced by Hypervalent Ions in Antimony(V) and Phosphorus(V) Porphyrins
Authors: Poddutoori Prashanth , Bayard Brandon J , Holzer Noah , Hamza Jam Riyan , Sharma Jatan , D'Souza Francis , Karr Paul
Published: September 2023

When main-group element phosphorus(V) or antimony(V) is inserted into the porphyrin cavity, the resulting phosphorus(V) porphyrin or antimony(V) porphyrin acquires several unique properties: (i) it remains as an excellent photosensitizer, (ii) introduces two chemically active axial bonds orthogonal to the plane of the porphyrin, (iii) attains strong oxidizing potentials, and (iv) induces a push-pull type intramolecular charge transfer. Our recent research has been focused on the latter two properties. The high oxidation number of the phosphorus and antimony ions makes the porphyrin central ring electron deficient. The presence of meso-substitutions (R) with moderate to high electron densities is sufficient to induce a push-pull type intramolecular electron transfer from peripheral aryl units to the central porphyrin ring. By varying the electron richness of the R unit, it is possible to modulate the charge transfer character. Steady-state and transient absorption studies were employed to establish the push-pull intramolecular charge transfer. Here, I will present some hypervalent porphyrins and discuss their structural, redox, and photophysical properties.

Figure 1
Synthesis and Excited State Charge Separation Involving Coordinated C60 of π-Extended Pyrazinepyrene Fused Zinc Phthalocyanines
Authors: Sastre-Santos Ángela
Published: September 2023

Polycyclic aromatic hydrocarbons (PAHs) play an important role in organic electronics.[1] To increase the stability and the conjugation, pyrene units could be further attached through heteroatoms to improve the photo/chemical stability to oxygen or light.[2] In terms of the synthesis of these types of large acenes through pyrene, many routes have been studied and one of the best protocols is to synthesize the quinoxaline derivative from the dione and the corresponding diamino subunit.[3]

Herein, we will present a series of pyrazinepyrene fused zinc phthalocyanines (ZnPc-Pyrn) as a new class of π-extended phthalocyanine systems. Bathochromically shifted absorption as a function of the number of pyrazinepyrene entities due to extended π-conjugation, and quenched fluorescence due to the presence of fused pyrazinepyrene were witnessed. The electronic structures of these phthalocyanines were probed by systematic computational and electrochemical studies while the excited state properties were examined by pump-probe spectroscopies operating at the femto- and nanosecond time scales. Like the excited singlet lifetimes, the excited triplet states also revealed diminished lifetimes with an increased number of pyrazinepyrene entities. Further, the coordinatively unsaturated zinc in these molecules was coordinated with phenyl imidazole functionalized fullerene, ImC60 to form a new series of donor-acceptor conjugates. Upon full characterization of these conjugates, the occurrence of excited-state charge separation was established by transient pump-probe spectroscopy covering wide temporal and spatial regions. With an increase in pyrazinepyrene entities, an increased rate of forward charge separation was witnessed while rate constants for charge recombination were slower resulting in the final lifetime of charge-separated states of about 40-50 ns, better than that reported earlier for a similar pristine zinc phthalocyanine derived dyad. [4]

Acknowledgments

Authors acknowledge the support from the Spanish Ministerio de Ciencia e Innovación (MICINN/FEDER, PID2020-117855RB-I00 to ASS) and Generalitat Valenciana (CIPROM/2021/059 and MFA/2022/028 to ASS) and US-National Science Foundation (2000988 to FD). The computational work was completed at the Holland Computing Center of the University of Nebraska, which receives support from the Nebraska Research Initiative.

References

1. Zhang, Y. Cao, N. S. Colella, Y. Liang, J.-L. Brédas, K. N. Houk, A. L. Briseno, Acc. Chem. Res.
2015, 48, 500-509.

2. T. M. Figueira-Duarte, K. Müllen, Rev.
2011, 111, 7260-7314; b) P. Jin, T. Song, J. Xiao, Q. Zhang, Asian J. Org. Chem.
2018, 7, 2130-2146.

3. a) H. Shang, Z. Xue, K. Wang, H. Liu, J. Jiang, Eur. J.
2017, 23, 8644-8651; b) T. Khoury, M. J. A. Crossley, Chem. Commun.
2007, 4851-4853; c) K. Kise, A. Osuka, Chem. Eur. J.
2019, 25, 15493-15497

4. J. Follana-Berná, Andrew Dawson,Sairaman Seetharaman, Paul A. Karr, Ángela Sastre-Santos, and Francis D’Souza, submitted.

Figure 1
Self-Assembly of Functional Organic Chromophores
Authors: Hill Jonathan P.
Published: September 2023

Aggregate structures of organic chromophores strongly affect their properties and so has become an active area of research. Self-assembly and supramolecular methods present important means to influence aggregation processes, and these have become active areas of research. We have studied the self-assembly of differently structured chromophore molecules with emphasis on porphyrins,1 pyrazinacenes,2 hexabenzocoronenes (HBC) and oligophenylenes (such as sexiphenyl), and the various methods of doing this including molecular design, surface assembly (under ambient or UHV conditions), and using interfacial media such as in the Langmuir and Langmuir-Blodgett techniques. For the latter, we have applied principles of amphiphilicity to generate on-interface structures,3 which can be lifted as multilayered films and exploited for the preparation of electronic devices.4 In this work, we will describe the self-assembly properties based on precipitation/gelation, assembly at solid surfaces, and interactions at an air-water interface. We will emphasize the molecular structure as a key feature including the effects of π-π stacking, conformational flexibility and amphiphilicity. Self-assembly and supramolecular techniques stand out as the most effective methods for obtaining nanomaterials having the molecule-level definition of structure important for any applications of the resulting materials.

References: 1) Y. Xie, M. Akada, Jonathan P. Hill, Q. Ji, R. Charvet, K. Ariga. Chem. Commun. (2011) 47, 2285–2287; 2) G. J. Richards, J. P. Hill. Acc. Chem. Res. (2021) 54, 3228–3240; 3) P. Mondal,G. Manna,T. Kamilya,M. Das,K. Ariga,G. J. Richards,J. P. Hill,S. Acharya. Adv. Mater. Interfaces (2022) 9, 2200209; 4) P. Mondal, et al. Submitted (2023).
Motifs in Porphyrin-Nanographene-Conjugate Chemistry
Authors: Gazetas Pascal , Schöll Kilian , Guldi Rebecca , Oleszak Christoph , Bozinovic Filip , Jux Norbert
Published: September 2023

Porphyrins form fascinating conjugates with nanographenes that possess exceptional properties. We will present various connectivity modes, such as direct bonds or coordination of N-containing nanographenes. In pursuit of this task, we prepared donor-acceptor moieties, which will be discussed as well. Some novel nanographenes that came into our hands during the synthesis of porphyrin conjugates including chiral moieties will also be shown.

References

M. Martin, D. Lungerich, P. Haines, F. Hampel, N. Jux, Angew.
Chem. Int. Ed.
2019, 59; 8932-8937.

M. Martin, D. Lungerich, F. Hampel, J. Langer, T. K. Ronson, N. Jux, Chem. Eur. J.
2019, 25, 15083-15090.

Hölzel, P. Haines, R. Kaur, D. Lungerich, N. Jux, D. M. Guldi, J. Am. Chem. Soc. 2022, 144, 8977-8986.

Figure 1
Electrochemical Investigations of Ru(L)(NO)(OPh) and Related Derivatives (L = Porphyrin or Bis(salicyl)Diiminate Ligand)
Authors: Shaw Michael , Zink Jeremy , Pumford Dustin , Warhausen Adam , Richter-Addo George , Ramuglia Anthony
Published: September 2023

A set of porphyrin and non-porphyrin complexes Ru(por)(NO)(OAr) and Ru(sal)(NO)(OAr’) complex have been prepared and studied by electrochemical and spectroelectrochemical methods (por = octaethylporphyrin, Ar = Ph, C6H4-2-NHC(=O)CF3; C6H3-2,6-(NHC(=O)CF3)2, sal = racemic (R,R/S,S)-N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2- cyclohexanediamine, N,N-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminobenzene; Ar’ = OPh, p-C6H4CF3). The consequence of 1-electron oxidation is loss of the aryloxide ligand, however the mechanism of that loss depends on the specific aryloxide ligand present in the complex. This conclusion is supported by cyclic voltammetry, DigiElch simulations, chemical oxidation studies, EPR spectroelectrochemistry and in-situ fiber-optic infrared spectroelectrochemistry measurements.
Hydrogen Catalysis By Macrocyclic Pyrrole Catalysts
Authors: Nocera Daniel G
Published: September 2023

We have designed hangman porphyrins for the study of hydrogen evolution catalysis. The hangman constructs utilize a pendant acid/base functionality within the secondary coordination sphere that is “hung” above the redox platform onto which the substrate binds. In this way, the delivery of a proton can precisely be controlled to substrate bonded to the metal of the macrocycle, thus ensuring efficient coupling between the proton and electron. Beyond the benefits of proton-coupled electron transfer (PCET), we have uncovered the impactful role of co-catalysts on electrocatalytic hydrogen production at the macrocyclic platform. Hydrogen evolution from a weak acid, acetic acid, occurs at extremely high rates in the presence of tertiary amine as a co-catalyst. These findings reveal controlled proton delivery and co-substrates as important design principles for creating efficient hydrogen evolution catalysts.
Modern Applications of Porphyrin-Based MOFs in Agriculture
Authors: Harvey Pierre D.
Published: September 2023

Nanosized metal-porphyrinic frameworks are an interesting class of porous electro- and photoactive materials finding applications in medicine (photodymanic therapy, photothermal therapy, drug delivery and chemotherapy, immunotherapy), [1], sanitary and antimicrobial devices [2], waste water purification [3], photocatalytic organic transformations [4], production of solar fuels [5], and more recently, in agriculture [6]. The fact that porphyrin derivatives are colored, they are prone for the photosensitization of singlet oxygen (1O2(g); a reactive oxygen species of type II) either at the solid state/air interfaces or in solution leading to applications listed above using visible light. In fact, they even do this efficiently. Reactive oxygen species of type I (for examples, H-O radical, HO-OH, superoxide radical, perhydroxyl radical, etc) are also photo-produced when given metals inside the porphyrins and metallic nodes in the frameworks are used, or when the metal-porphyrinic frameworks form a composite with another semiconductor. Moreover, the size of the nanoparticles can be tailored. All of these properties are cleverly exploited in the field of agriculture and include the following applications: controlled delivery of pesticides and agro-chemicals, detection of pesticides and pathogenic metals, elimination of pesticides and toxic metals, and photodynamic antimicrobial activity, and the nanosized metal-porphyrinic frameworks also have an important implication in food safety. This presentation will describe these features along with new experimental results.

References:

[1] Harvey, Pierre D.; Ple, Jessica, Journal of Inorganic and Organometallic Polymers and Materials (2021), 31(7), 2715-2756.

[2] Schlachter, Adrien; Asselin, Paul; Harvey, Pierre D., ACS Applied Materials & Interfaces (2021), 13(23), 26651-26672.

[3] Harvey, Pierre D., Journal of Materials Chemistry C, (2021), 9(47), 16885-16910.

[4] Harvey, Pierre D., Journal of Porphyrins and Phthalocyanines (2021), 25(7/8), 583-604.

[5] Asselin, Paul; Harvey, Pierre D. ACS Applied Nano Materials (2022), 5(5), 6055-6082.

[6] Sajjadinezhad, Seyed Mehrzad; Tanner, Kevin; Harvey, Pierre D., Journal of Materials Chemistry B, (2022), 10(44), 9054-9080.
Porphyrins – Effective Photocatalysts for Red Light-Induced Functionalizations of Biomolecules
Authors: Gryko Dorota
Published: September 2023

Recently, photoredox catalysis has begun to influence molecular biology and medical sciences for its mild conditions for generating highly reactive species (i.e., radicals), enabling novel and selective functionalisations of biomolecules.[1] In line with this, porphyrins, which can transfer energy (photosensitization) or electrons (photoredox catalysis) when exposure to light, seem to be highly advantageous. Given that their electron absorption shows a characteristic Soret band at 420 nm with a high molar extinction coefficient (105 M-1 cm-1),[2] they have been mainly used in blue-light-induced reactions. These molecules, however, absorb red light (four Q-bands at 518, 553, 592 and 648 nm with molar extinction coefficients of 104 M-1 cm), which has the benefit of low energy, lower health risks,[3] and more in-depth penetration of various media.[4]

Fig. 1: Porphyrins in red lightinduced transformations

We established that due to their diverse photophysical properties, porphyrins promote photoinduced electron transfer events under red light irradiation.[5] They act as effective photooxidants (alkylation of carbonyl compounds, thiol-ne reaction and reductive decarboxylation) and photoreductants (in arylation of heteroarenes, selenylation, thiolation and reduction of nitro compounds). These bioinspired photocatalysts exhibit features that outperform other catalysts operating under red light, as they are really non-toxic and can be applied in biological systems. Thus, we believe that free-radical porphyrins are a valuable contribution to the set of red-light photocatalysts, and this study will lead to more practical biosynthetic applications.

References

[1] Liu, W.; Watson, E. E.; Winssinger, N. Chim.
Acta
2021, 104, e202100179

[2] Giovanetti, R. The Use of Spectrophotometry UV-Vis for the Study of Porphyrins, Macro to Nano Spectroscopy, 2012, ISBN 978-953-51-0664-7, InTech

[3] Smith, A. M.; Mancini, M. C.; Nie, S. Nature Nanotechnology
2009, 4, 710–711.

[4] Szacilowski, K.; Macyk, W.; Drzewiecka-Matuscek, A.; Brindell, M.; Stochel, G. Rev.
2005, 105, 2647–2694.

[5] Rybicka-Jasińska, K.; Wdowik, T.; Łuczak, K.; Wierzba, A.J.; Drapała, O.; Gryko, D. ACS Org. Inorg. Au
2022, 2, 422–426.

Figure 1
Biocatalytic Intramolecular C-H Aminations Via Engineered Heme Proteins: Full Reaction Pathways and Axial Ligand Effects
Authors: Wei Yang , Conklin Melissa , Zhang Yong
Published: September 2023

Engineered heme protein biocatalysts provide an efficient and sustainable approach to develop amine-containing compounds through C-H amination. A quantum chemical study to reveal the complete heme catalyzed intramolecular C-H amination pathway and protein axial ligand effect was reported, using reactions of an experimentally used arylsulfonylazide with hemes containing L = none, SH-, MeO-, and MeOH to simulate no axial ligand, negatively charged Cys and Ser ligands, and a neutral ligand for comparison. Nitrene formation was found as the overall rate-determining step (RDS) and the catalyst with Ser ligand has the best reactivity, consistent with experimental reports. Both RDS and non-RDS (nitrene transfer) transition states follow the barrier trend of MeO- < SH- < MeOH < None due to the charge donation capability of the axial ligand to influence the key charge transfer process as the electronic driving forces. Results also provide new ideas for future biocatalyst design with enhanced reactivities.