bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of NaY9Si6O26:Yb3+ Phosphor with High Thermal Stability and Its Crystals Structure and Luminescent Properties for NIR Anti-Counterfeiting
Authors: Kim Sun Woog , Kang Taewook , Park Young Ji 
Published: February 2024

Near-infrared (NIR) radiation has attracted considerable industrial and research interest. NIR emission has promising potential for varied applications, mostly related to the characterization of chemicals, security, pharmaceutical, medical, cosmetic, food, and agricultural industries, which contribute to the advancement of modern technology. Emission sources such as tungsten halogen lamps, light emitting diodes (LEDs) and phosphor converted LEDs (pc-LEDs) can emit in the infrared range. Among these, NIR pc-LED is considered as the most suitable emission source because it provides adequate emission, high efficiency, long lifetime and excellent durability. In recent years, studies have been conducted to adjust the emission spectrum suitable for NIR phosphors and to improve quantum efficiency in order to apply them to advanced applications and devices of pc-LEDs.
Recently, it is necessary to develop a material capable of specifying the near-infrared emission wavelength of near-infrared excitation beyond ultraviolet excitation infrared for advanced anti-counterfeiting against advanced counterfeiting technology. In the present study, a rare-earth-containing compound doped with an activator was used as a host system for a near-infrared phosphor to develop suitable luminescent properties. Yb3+-doped NaY9Si6O26 phosphors were synthesized using a conventional solid-state reaction method. The main phase of the synthesized phosphor samples exhibited a hexagonal structure NaY9Si6O26 phase, and had an angular-shape with an average grain size of 1-3 μm. The NaY9Si6O26:Yb3+ phosphors showed a broad near-infrared emission from 950 to 1100 nm, which was attributed to the 2F5/2 → 2F7/2 transition of Yb3+ ions under 270 and 920 nm excitation. The excitation spectra, recorded by monitoring the emission at 985 nm, showed two bands in the ultraviolet and infrared regions The excellent thermal stability of NaY9Si6O26:Yb3+ phosphor was evident from the fact that the relative PL intensity of NaY9Si6O26:Yb3+ phosphor was 82% of the initial PL intensity at 300 °C, and the thermal degradation was negligible after cooling. These results suggest NaY9Si6O26:Yb3+ phosphors are promising next-generation candidates for advanced anti-counterfeiting applications.
(Invited) Electrocatalytic Syntheses with Interfacial Control
Authors: Wuttig Anna 
Published: February 2024

Synthesis driven by renewable electricity offers a sustainable, scalable, decentralized, and energy-efficient route to furnish value-added products. As all electrocatalytic reactions occur at the phase boundary between conductive solids and liquid electrolytes, the discovery, design, and manipulation of selective electricity-driven reactivity demands new methods to probe and tune this interface and predict how interfacial structural changes influence reaction selectivity.
The functionalization of aldehydes and ketones with organic halide electrophiles remains a privileged reaction class to construct C(sp3)‒C(sp3) bonds. Translation to molecular catalytic strategies remains challenging due to competitive side reactivity imposed by radical intermediates following sp3 organic halide activation. Our group has uncovered an alternative paradigm that deploys catalytic electrode surfaces to develop reductive fragment-based electrophile coupling reactions. Using in-situ spectroscopy and electrochemical analyses, we reveal the “black box” of the catalytic interface. The addition of Lewis acids pre-organizes the surface, enabling a carbon-centered radical (obtained via electrocatalytic activation) to efficiently add to the carbonyl. Our studies lay a foundation to develop sustainable synthetic methodologies by tuning the interfacial structure at catalytic, reusable electrodes at the molecular level.
TEMPO-Modified Polymethacrylates As Mediators in Electrosynthesis - Influence of the Molecular Weight on Redox Properties and Electrocatalytic Activity
Authors: Prudlik Adrian , Mohebbati Nayereh , Francke Robert 
Published: February 2024

Compared to direct electrolysis, homogeneous electrocatalysis often gains better selectivity and higher yields with less energy consumption.[1] However, additional separation steps are necessary for product isolation and catalyst recycling increasing waste generation and adding expenses. Polymerized electrocatalysts (polymediators) can be separated and reused by membrane filtration and therefore simplify the separation process.[2] Tuning the molecular weight distribution represents a possibility for optimization of the overall reaction rate that is currently under investigation in our laboratory.
We used cyclic voltammetry as a tool to analyze the electrochemical behavior of two model compounds (ACT and BTM) as well as TEMPO-modified polymethacrylates (TPMA) of different molecular weight (MW) distributions in view of anodic alcohol oxidation. The MW distributions were adjusted using the RAFT technique,[3] leading to well-defined polymediators with average MWs from 2.5 kDa to 126 kDa and monomodal weight distributions.
While the electrochemical properties of all polymers (redox potential, current enhancements) are similar, the diffusion rate of the polymediators is curbed with increasing MW, also decreasing the overall reaction rate during electrolysis, and increasing reaction time.[4] The remaining task is to find an optimal operating range in which both reasonable filtration efficiencies and sufficient current densities are achieved.

References

[1] R. Francke, R. D. Little. Chem. Soc. Rev.
2014,
43, 2492.
[2] B. Schille, N. O. Giltzau, R. Francke, Angew. Chem. 2018, 130, 429.
[3] N. Mohebbati, A. Prudlik, A. Scherkus, A. Gudkova, R. Francke, ChemElectroChem,
2021
8, 3837.
[4] A. Prudlik, N. Mohebbati, L. Hildebrandt, R. Francke, Chem. Eur. J.
2023, 29, e202202730.

Figure 1
Markov State Models for Electrostatic Channeling in Bioelectrocatalysis
Authors: Wark Christina , Xie Yan , Calabrese Barton Scott 
Published: February 2024

Multistep biocatalytic cascades benefit from channeling mechanisms that guide intermediate transport between active sites. Channeling approaches such as electrostatic interactions and steric confinement are best exemplified in natural biocatalytic complexes such as tryptophan synthase and malate dehydrogenase–citrate synthase, but are also amenable to application in de novo cascades designed to accomplish chemical conversion and energy production.
We have recently conducted an extensive computational study of the Malate Dehydrogenase–Citrate Synthase (MDH-CS) complex, which displays a positively charged patch on its surface, capably of electrostatically channeling a negatively-charged oxaloacetate intermediate. Our collaborators have demonstrated experimentally that mutation of residues in the positively-charged patch can strongly effect intermediate transport, as measured by lag time, the time required for the second of a two-reaction cascade to approach steady state [1].
Using classical molecular dynamics approaches to study the transport of oxaloacetate in the presence of the charged surface, we created a Markov State model that effectively maps the prevalence of the intermediate across the enzyme surface as well as in bulk solution. Building the model involved seeding the possible states of the intermediate using metadynamics to force the intermediate out of low-energy states and to explore the overall energy landscape. Once assembled, this model enables us to study the dominant pathways of intermediate transport, for example contrasting transport along the charged enzyme surface with diffusion into the bulk solution. A “hub score” approach enabled identification of key residues that control intermediate traversal over the charged surface, and we are able to calculate pathway efficiency that is directly relatable to lag time [2].
We will discuss a new, fast finite-difference approach to predict lag times for these multidimensional complexes. The steady-state transition matrix of the Markov state model is easily converted to a material balance for each node in the network. Using the model, the lag time of MDH-CS was determined computationally to be comparable to experiment for both the original and mutant complex. Using the model, the the dynamics of each of the four possible reaction pathways between the the two source (MDH) active sites and the two sink (CS) sites could be studied independently. This analysis provides a dynamic model for intermediate transport in an electrostatically channeled system, and can be used as a predictive tool to provide mechanistic insight into path dominance.

B. Bulutoglu, K. E. Garcia, F. Wu, S. D. Minteer and S. Banta, ACS Chem. Bio., 11, 2847–2853 (2016). doi:10/f9c5cp

Y. Xie, S. D. Minteer, S. Banta and S. C. Barton, ACS Nanosci. Au, 2, 414 (2022). doi:10/gqkvtq
Using Enzymes to Understand and Control the Local Environment of Catalysis
Authors: Cobb Samuel J. , Dharani Azim M , Oliveira Ana Rita , Pereira Inês A. C. , Reisner Erwin 
Published: February 2024

Local environments within porous electrodes are an inherent, but often neglected component of catalysis as the local conversion of reactants to products means catalysis occurs in a very different environment to bulk solution. By understanding and modifying these local environments using a combination of experimental and computational techniques, we show how to improve the performance of electrocatalytic reactions to address the climate crisis by efficiently converting renewable energy to chemical fuels. The selectivity and activity of enzymes means they are ideal model catalysts that can guide the design of synthetic systems. However, they must be in an environment that is close to their optimal to operate efficiently, with small changes in properties such as pH drastically affecting their activity. By optimising their local environment, the rates of fuel formation can be drastically (>18×) increased.[1] We also demonstrate the crucial role of CO2 hydration kinetics on the local pH and CO2 concentration using the enzyme Carbonic Anhydrase co-immobilised with Formate Dehydrogenase.[2] Carbonic Anhydrase catalyses CO2 hydration, causing CO2 to act as a better buffer to mitigate changes in the local pH environment allowing the system to operate closer to its optimal and how this contrasts with heterogeneous CO2 reduction. (fig. 1a)
We extend this approach to low CO2 concentrations, taking inspiration from the natural carboxysome to develop a system where Formate Dehydrogenase and Carbonic Anhydrase are co-immobilised in a nanoconfined structure to improve low CO2 concentration utilisation. (fig. 1b).[3] The electrolysis of dilute CO2 streams suffers from low concentrations of dissolved substrate and its rapid depletion at the electrolyte-electrocatalyst interface. These limitations require first energy-intensive CO2 capture and concentration, before electrolyzers can achieve acceptable performances. For direct electrocatalytic CO2 reduction from low-concentration sources, we introduce a strategy that mimics the carboxysome in cyanobacteria by utilizing microcompartments with nanoconfined enzymes in a porous electrode. Carbonic Anhydrase accelerates CO2 hydration kinetics and minimizes substrate depletion by making all dissolved carbon available for utilization, while a highly efficient formate dehydrogenase reduces CO2 cleanly to formate; down to even atmospheric concentrations of CO2. This bio-inspired concept demonstrates that the carboxysome provides a viable blueprint for the reduction of low-concentration CO2 streams to chemicals by using all forms of dissolved carbon.

References

[1] E. E. Moore, S. J. Cobb et al., Proc. Natl. Acad. Sci. USA
2022,119, e2114097119
[2] S. J. Cobb et al., Nat. Chem.
2022, 14, 417 – 424
[3] S. J. Cobb et al., Angew. Chem. Int. Ed.,2023
Just Accepted, DOI: 10.1002/anie.202218782

Figure 1
Electrosynthetic Carboxylation of Biomass-Derived Compounds in Ionic Liquids
Authors: Steffensen Astrid Kjær , Lundberg Helena , Riisager Anders 
Published: February 2024

Chemical production from renewable biomass and CO2 is a sustainable alternative to the current fossil based chemical industry as it will enable significant reduction of greenhouse gas emissions. CO2 is a desirable chemical building block as it is abundant and steadily becoming more available as carbon capture technologies are maturing. However, activation and valorization of CO2 remains a challenge due to its thermodynamic stability and kinetic inertness. CO2 activation has been demonstrated with thermal, (photo)catalytic and electrochemical methods, and especially the electrochemical approach allows for mild reaction conditions and high efficiency. In this context, the synthesis of carboxylic acids by electrosynthetic carboxylation represents an interesting strategy for valorization of biomass-derived alcohols and CO2.
In electrosynthesis, a supporting electrolyte salt is needed in the reaction medium to ensure high conductivity. A major drawback of using such a supporting electrolyte salt is increased waste generation. However, by replacing supporting electrolyte salts with recyclable ionic liquids the waste generation can in theory be avoided. In addition, ionic liquids can provide a highly conducting reaction medium with a sufficiently large electrochemical window allowing CO2 activation to take place. Furthermore, room temperature ionic liquids are especially suitable for electrosynthetic carboxylation reactions due to their high CO2 absorption capacity.
In this work, we present preliminary results, including cyclic voltammetry and reaction optimization studies, for electrosynthetic C-O activation and carboxylation of biomass-derived compounds with room temperature ionic liquids as electrolytes.
Electroreductive Desulfurative Transformations with Thioethers As Alkyl Radical Precursor
Authors: Kuzmin Julius , Röckl Johannes , Schwarz Nils , Djossou Jonas , Ahumada Guillermo , Ahlquist Mårten , Kuzmin Julius 
Published: February 2024

Thioethers are highly prevalent functional groups in organic compounds of natural and
synthetic origin but remain remarkably underexplored as starting materials in
desulfurative transformations. As such, new synthetic methods are highly desirable to
unlock the potential of the compound class and electrochemistry is an ideal tool to
enable new reactivity and selectivity under mild conditions.
We target aryl alkyl thioethers, which outperformes their well-established sulfone
analogue, to form C-C bonds through the reactive intermediate. Cleaving the bond in
the precense of a hydrogen donor results in the dehydrosulfurisation product. Doing the
same reaction in the precense of CO2 or electron deficient alkene results either in the
carboxylic acid or the C(sp3)–C(sp3) product.

Figure 1
Understanding the Effects of Transition Metal Impurities on Nickel (oxy) Hydroxide Electrocatalysts in Alkaline Media
Authors: Marquez-Montes Raul A. , Kawashima Kenta , Son Yoon Jun , Kalokowski Emma , Espinosa Michael , Smith Lettie A. , Chukwuneke Chikaodili E. , Miller Nathan , Mullins Charles Buddie 
Published: February 2024

Nickel-based materials are widely used as critical components of electrochemical energy devices, including alkaline electrolyzers, capacitors, and alkaline batteries. These materials are often preferred because of their availability and low cost compared to precious metals, which makes them excellent candidates for accomplishing the decarbonization goals and electrifying our society. However, several studies have demonstrated that the incorporation of trace impurities from commercial alkaline electrolytes induces significant changes in the intrinsic activity, pseudocapacitance, and stability of Ni-based materials, resulting in erroneous descriptions of their performance. Thus, having a better understanding of the effects of these impurities will lead to practical ways to prevent or control their impact on electrochemical energy devices.
In this work, we study the incorporation of transition metals (i.e., Fe, Co, Cu) that form insoluble hydroxides in alkaline media over nickel (oxy) hydroxide electrocatalysts. We systematically examine how these trace impurities modify the OER activity, stability, and the pseudocapacitive properties of NiOOH. As depicted in Figure 1, KOH electrolytes containing trace impurities of Fe and Co induce significant changes in the OER onset potential of Ni(OH)2/NiOOH electrocatalysts, according to the irreversible charge increase measured through coulovoltammetry (QV) curves. Moreover, distinct redox peaks can be seen for each scenario. After aging in purified KOH electrolyte (Fig. 1a), the cyclic voltammogram (CV) of Ni(OH)2/NiOOH exhibits four oxidation peaks that can be ascribed to a mixture of both α and β structural phases (Fig. 1b) while aging in Fe-unpurified KOH promotes the α phase and shifts the redox peak anodically (Fig. 1c). Aging in Co-unpurified KOH promotes a more ordered β structural phase without changing the OER activity significantly (Fig. 1d), which is desirable for pseudocapacitive materials. Additional experiments examining the OER activity, stability, and capacitance provide valuable insights into these impurities, and specific strategies to prevent and minimize their effects will be discussed. Overall, this work illustrates the importance of tracking trace metal impurities in alkaline electrolytes to minimize undesirable effects in electrochemical energy devices.

Figure 1
Surface Dual-Modification of Nano-Cu2o for Controlling CO2 Electrochemical Reduction to Ethylene and Syngas
Authors: Luo Haiqiang , Li Bo , Ma Jian-Gong , Cheng Peng 
Published: February 2024

Carbon dioxide (CO2) is an important substance in the natural carbon cycle, and the gradual increase of CO2 emissions has exceeded the amount that can be absorbed by the nature, which has brought a huge impact on climate conditions and ecological environment. In addition, CO2 is an important C1 resource, and it is of great significance to convert it by electrochemical methods to important chemical raw materials (such as ethylene and syngas) needed for human life. Cu2O is an ideal electrocatalyst due to its relatively low cost and unique product selectivity, as well as the abundant Cu reserves on the earth. However, there is still a lack of systematic studies on the improvement of the C2H4 selectivity of Cu2O-based catalyst and the regulation of product selectivity.
In this work, different exposed facet nano-Cu2O were obtained by induction of reducing agent. Combined with in-situ characterization and theoretical calculation, it was found that the terrace × step structure (332) crystal surface can significantly reduce the free energy of C-C coupling process, and greatly improve the selectivity of electrochemical CO2 reduction to C2H4, which is the highest value (74.1%) obtained by Cu2O based catalyst with neutral electrolyte.
Subsequently, the ZIF-8 shell is introduced in-situ on the surface of Cu2O nanoparticles. The coated ZIF-8 shell effectively regulates the hydrophilic and hydrophobic environment of the material, and provides a material exchange channel for reactants and product molecules simultaneously, which promote the desorption of CO molecules and improve the adsorption of CO2, realizing the switch of product from C2H4 to syngas.
In carbon dioxide reduction, it is an important strategy to modify the surface of metal/metal oxide by interface engineering to regulate the microenvironment at the reaction interface. In this paper, from the aspects of material design, synthesis and regulation of reaction products, the great advantages of facet structure and MOFs for improving the stability and activity of catalyst are demonstrated. Combined with in situ characterization and theoretical calculation, a new idea is provided for the design of efficient carbon dioxide electroreduction catalyst in the future.

Figure 1
Decoupled Electrolysis Based on Pseudocapacitive Auxiliary Electrodes: Mechanism and Enhancement Strategies
Authors: Sutka Andris , Vanags Martins , Iesalnieks Mairis 
Published: February 2024

Hydrogen is the way for connecting the renewable energy plants and consumers. However, achieving cheap, widespread hydrogen production and storage is complicated task. For hydrogen production the alkaline and acidic membrane electrolysers are used most widely. The membrane electrolysers have their limits, for example high standard potential of water splitting reaction, moderate efficiency, high cost and low durability. Decoupling oxygen evaluation reaction (OER) and hydrogen evaluation reaction (HER) is promising strategy to avoid using of membrane. Water electrolysis in separate cells was reported in 2017 by A. Landman et al., reaching the efficiency of 58% [1].
In 2022, we reported for the first time the amphoteric decoupled electrolysis by combining acid and alkaline cells [2]. The efficiency was enhanced due to reduced standard potential for water splitting by realizing HER in acidic environment but OER in alkaline. For maintaining decoupled amphoteric electrolysis, we connected acid and alkaline cell with the primary Pt electrodes and pseudocapacitive auxiliary electrodes (AE). For acid cell the AE electrode based on WO3 was used while for the alkaline cell electrodes based on Ni(OH)2. In proposed electrolyser two separate working cycles can be distinguished – different chemical processes occur at different polarities applied between primary Pt electrodes. The potential for gas generation depends on the polarity of the applied potential due to different chemical processes. In both polarities, hydrogen and oxygen are generated in separate cells. At the first cycle, ions are diffusing into the AEs and gases are generated with the Faradaic efficiency of 98 % and energetical efficiency of 43 %. At the second cycle, ions are released from AEs and gasses are generated with the Faradaic efficiency of 98 % and energetical efficiency of 201 %, providing the total energetical efficiency for whole operation of 71 %.
Herein we will discuss the effect of acid OER catalyst or the structure and composition of AEs on the performance of decoupled electrolysis, illuminating the pathways for bringing this concept as the main strategy for water splitting.

References

[1] A. Landman, H. Dotan, G.E. Shter, M. Wullenkord, A. Houaijia, A. Maljusch, G.S. Grader, A. Rothschild, Photoelectrochemical water splitting in separate oxygen and hydrogen cells, Nature Materials 16 (2017) 646-651.
[2] M. Vanags, G. Kulikovskis, J. Kostjukovs, L. Jekabsons, A. Sarakovskis, K. Smits, L. Bikse, A. Šutka, Membrane-less amphoteric decoupled water electrolysis using WO3 and Ni(OH)2 auxiliary electrodes, Energy Environ. Sci., 15 (2022) 2021-2028.