bluuebunny/crossref_metadata_2025 huggingface dataset:
Na-Sn Alloy Regulated Protective Coating Layer Enables the Long Life Dendrite-Free Sodium Metal Batteries
Authors: Moorthy Megala , Ganesan Bala Krishnan , Dhansekaran Hariharan , Kim Yeong-A , Song Jeong-Hyeon , Lee Yun-Sung
Published: February 2024

Sodium metal anodes are highlighted as the most potential candidates for next-generation batteries due to their high theoretical capacity (1166 mAh/g), low electrochemical potential (-2.71 V vs standard hydrogen electrode), and cheaper material cost. However, practical application of sodium metal batteries is limited due to the uneven solid electrolyte interphase layer and insignificant coulombic efficiency. Designing a protective coating layer as an artificial solid electrolyte interphase layer on a sodium metal anode is one of the main approaches to maintaining the homogenous deposition and long-term stability during the process of electrochemical plating/stripping. Herein, a protective layer of (Na-Sn) alloy and Na-Cl insulator was formed by establishing the spontaneous self-alloying reaction. Most importantly, the proposed Na-Sn metal alloy layer has high ionic conductivity, stable chemical/electrochemical interphase, and robustness to enhance the homogenous Na ion deposition and prevent the uncontrollable sodium dendrites. Based on these effects, using the Na-Sn alloy symmetric cell exhibits the stable electrochemical performance (500 h at 2 mA/cm2 & 2 mAh areal capacity). The Full cell was assembled using the Na3V2(PO4)3 cathode and Na-Sn alloy over sodium metal anode in diglyme electrolyte, showing excellent cycle stability up to 100 cycles at 1 C rate and discharge capacity of 168 mAh/g at 0.1 C rate. This work presents a new technique to produce a uniform Na ion deposition and safe dendrites-free sodium metal batteries (SMBs).
(Invited) Integration of Sulfide and Halide Based Solid-Electrolyte Membranes with Li-Ion Cathodes
Authors: Nanda Jagjit
Published: February 2024

Lithium metal-based batteries (LMBs) employ a Li-metal anode coupled with a conventional high voltage ceramic cathode. The higher capacity of Li vs. graphite (3861 mAh g-1
vs. 372 mAh g-1) combined with high voltage cathodes results in an over 50% increase in the specific energy versus conventional ion-insertion anodes. All-solid-state batteries (ASSBs) can achieve the sought-after high energies when employing cathodes such as LiNi0.8Mn0.1Co0.1O2 (NMC811) and LiNi0.5Mn1.5O4. Having the SEs be as thin as practically possible maximizes the energy density of the cells by both reducing the total weight and achieving voltage window closer to the theoretical limit due to reduced impedance. Likewise, a thin metal anode is sought-after since it reduces the cell weight as well as the risk associated with accidental ignition of the metal. Argyrodite SEs such as Li6PS5Cl (LPSCl) and Li6PS5Br (LPSBr) form terminal decomposition products such as Li3P and Li2S at the metal anode. However, it is the presence of halide-based decomposition products such as LiCl that kinetically stabilizes the interface. For example, substantially improved ASSB performance has been achieved with “sandwich” structures such as LPSCl/LGPS/LPSCl.

The talk will focus on the recent approaches to improve interfacial stability of sulfide based solid electrolytes (SEs) with Li-metal and NMC based cathodes for SSB’s. A comparative evaluation of SSB performance between Argyrodite (Li6PS5X, X= Cl, Br) and halide-based SE (Li3ACl6, A = In, Y) using them as a separator and catholyte will be presented. Overall, these results demonstrate that incorporating oxidatively stable SEs in composite cathodes does not necessarily ensure the formation of robust NMC/SE interfaces, and cumulative irreversible capacity losses in such cells can yield rapid performance decline. Rather than SE decomposition, the dominant cause for capacity fade in SSBs is due to active material isolation resulting from repeated volume changes during cycling. Further, additional understanding of the mechanics of solid-solid interfaces and their dynamical evolution during SSB operation will be critical to address key performance bottlenecks for Li metal SSBs.
Crystal Orientation-Dependent Interface Compatibility in the Oxide Composite Cathode by in Situ Heating Transmission Electron Microscopy
Authors: Lee Sunyoung , Park Hayoung , Park Jungwon , Kang Kisuk
Published: February 2024

All-solid-state batteries (ASSBs) with oxide-based solid electrolytes are getting prominence as a forthcoming battery system capable of overcoming the drawbacks of current lithium-ion batteries by satisfying the expanding demand for high energy density and safety. However, the poor interfacial contact between cathode active materials and solid electrolytes, at which lithium ions diffuse and the charge transfer occurs, is a major concern for practical utilization. Although the co-sintering process at high temperatures is essential to achieve an intimate interface contact, excessive thermal energy reversely accelerates the interfacial degradation reaction, of which the mechanism has been still unexplored. Here, using an epitaxial model system in which the crystal orientations of the Li(Ni1/3Co1/3Mn1/3)O2 cathode and Li3xLa(2/3)-x⎕(1/3)-2xTiO3 solid electrolyte are controlled, we directly probe the interfacial reaction in real-time during heating by in situ heating transmission electron microscopy, and investigate the impact of the crystal orientation at the interface on the interfacial reaction mechanism and kinetics. In situ observation reveals that the interfacial reactions are highly dependent on the crystal orientation at the interface involving the onset temperature of the reaction, the diffusion behavior of lithium ions, the intermediate states, and the overall degradation mechanism between the active material and the solid electrolyte. The interfacial degradation during heating increases the charge transfer resistance between the cathode active material and the solid electrolyte, and the increasing tendency of the resistance is closely related to the crystal orientation-dependent interfacial degradation.
Microstructure- and Surface-Modified Ni-Rich Layered Cathode for High-Energy All-Solid-State Batteries
Authors: Yu Tae-Yeon , Kim Un-Hyuck , Lee Jin wook , Sun Yang-Kook
Published: February 2024

Li-ion batteries, which have been widely commercialized in the portable electronic devices and electric vehicles, pose a potential safety risk because the flammable liquid electrolyte can cause explosions under certain conditions. All-solid-state batteries (ASSBs) are promising candidates due to the potentially improved safety as well as high energy density. However, realizing high energy density ASSBs by employing Ni-rich layered cathode is difficult because of the microcrack with detrimental volume contraction near charge end as well as side reaction with solid electrolytes (SE). To overcome these limitations, this study show that the simultaneous boron doping and coating of a Ni-rich Li[Ni0.9Co0.05Mn0.05]O2 (NCM90) cathode, which modifies the cathode microstructure and protects cathode-SE interface, respectively, afford an ASSB that demonstrates an initial discharge capacity of 214 mAh g-1 and cycles stably 300 cycles with minimal capacity fading. The proposed dual treatment of the NCM90 cathode offers a viable approach to realizing a high energy density ASSBs with long cycle life by fracture-toughening the Ni-rich cathode and constructing a mechanically and chemically robust cathode-SE interface.
A Glass-Interphase for Highly Reversible and Stable RT-Na/S Batteries
Authors: Soni Chhail Bihari , Soni Chhail
Published: February 2024

Owing to the high theoretical specific capacity (1165 mA h g-1), high natural abundance, and low redox potential (-2.71 V vs standard hydrogen electrode), sodium metal is considered as an ideal anode material for the next-generation high-energy batteries. Though, a high-temperature variant of the sodium-sulfur batteries has already been commercialized, its compromised safety (due to high-temperature operation, 250 – 300 ⁰C) has triggered the research interest in developing its room-temperature analogue. At room-temperature, the thermodynamic instability of Na metal with the liquid electrolytes often leads to develop a thick and chemically unstable interphase, often called the solid electrolyte interphase (SEI). Upon Na plating/stripping, the SEI grows and dissolves repeatedly, results in consuming both the Na anode and the electrolyte inventory. The Na dendrites, the primary unknown risk associated with Na metal-based batteries, are inclined to develop from the fractured sites of the SEI. The SEI exfoliation can be attributed to weak chemical adhesion between the SEI and the Na metal anode. Functional additives, engineered solvents, and the high concentration electrolytes have often been used to alter the mechanical and electrochemical properties of the SEI. It is apparent that, a stable and durable SEI is the key to creating a secure, dendrite-free, and long-lasting RT-Na/S batteries.

More recently, the idea of glass-electrolytes to stabilize the metal anodes is disclosed by the Nobel laureate Prof. J. Goodenough. The glass-electrolyte is used to suppress the dendrite growth and ensured improved safety of the high-energy metal-sulfur batteries. However, the cell experiences a huge interfacial resistance due to metal anode/glass-electrolyte interface.

The present work relates to the development of a glass-interphase for RT-Na/S batteries. The interphase is grown directly over the sodium metal anode through a simple and scalable approach. To growth the interphase, a novel organic molecule is used to facilitate the formation of the glass-interphase, and called as “glass-interphase forming additive (GIFA). In general, GIFAs contains the hydrolysable group, which is commonly an amine, acyloxy, alkoxy, or halogen on one side, and one Si atom. It contains organo-functional group, such as epoxide, on other side. The presence of oxide or hydroxide is essential in realizing interaction of GIFA with the sodium metal surface.
(Invited) Coupling of Electrochemistry with Surface Science and Computational Modeling to Understand Nanoparticle Electrocatalysts
Authors: Deng Xingyi , Alfonso Dominic , Sorescu Dan C. , Nguyen Phan Thuy Duong , Kauffman Douglas
Published: February 2024

We investigated nanoparticle electrocatalysts in oxygen evolution reaction (OER) and CO2 reduction reaction (CO2RR) via an approach coupling electrochemistry with ultra-high vacuum (UHV) surface science and computational modeling. Well-defined nanoparticle electrocatalysts such as Fe2O3, NiFeOx, and Ag, were prepared in the UHV chamber via physical vapor deposition (PVD) and characterized with surface science techniques including X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM), followed by electrochemistry measurements to establish the structure-property relationships in OER and CO2RR. Calculations based on density functional theory (DFT) and microkinetic modeling (MKM) were then implemented to gain fundamental insight into these systems. We observed the edge-enhanced OER activity of Au-supported, ultra-thin Fe2O3 electrocatalysts and revealed incorporation of Ni at the edge sites (NiFeOx) further boosting their OER activity. We also resolved the size-dependent transition between CO2RR and H2 evolution reaction (HER) selectivity in sub-5 nm Ag electrocatalysts and identified an effective minimum size limit of ∼4 nm for active and selective Ag catalysts: particle diameters below this range experienced increased H2 evolutions due to a high population of Ag edge sites; and larger diameter particles favored CO2RR as the population of Ag(100) surface sites grew but will begin to lose catalyst utilization based on total metal masses.
(Invited) Current Status and Progress in Anion Exchange Membrane Electrolysis
Authors: Vincent Immanuel , Fernandez Ekain , Francisco Jose Fernandez Carretero , Velasco Ion , Garcia Alberto
Published: February 2024

Anion exchange membrane (AEM) electrolysis is a promising solution for large-scale hydrogen production from renewable energy resources. However, the performance of AEM electrolysis is still lower than what can be achieved with conventional technologies. Materials chemistry, MEA designs, and optimal operation conditions have driven recent advancements. Majority of the AEM research has focused on improving ionic conductivity and alkaline stability. Many AEMs exceed 0.1 S/cm (at 60–80 °C), however stability at temperatures above 60 °C needs improvement. Oxygen evolution reaction OER remains a bottleneck. The active-site mechanism of NiFe catalysts is disputed, and their long-term stability is unknown. Co boosts NiFe catalyst conductivity. Carbon-supported Pt dominates the hydrogen evolution process (HER), whereas PtNi alloys and clusters of Ni(OH)2 on Pt compete. Well-dispersed Ru nanoparticles on functionalized high-surface-area carbon substrates show promising HER actions. New in situ methods, AEMWE evaluation processes, and catalyst-structure designs could help the field advance faster. Nonetheless, single AEM water electrolyzer cells have operated for several thousand hours at 60 °C and 1 A/cm2.
(Invited) Transition Metals in Ni/GDC for the Reversible Solid Oxide Cell Operation: Optimization of the Mo-Au-Ni Synergy and Further Enhancement Via Substitution of Mo with Fe
Authors: Zaravelis Fotios , Sygellou Lamprini , Souvalioti Athina , Niakolas Dimitris K.
Published: February 2024

The study focused on the elucidation of the synergistic interaction of different wt.% loadings of Mo and Au in Ni/GDC, with the objective to find their optimum content for enhanced rSOC performance. In addition, the promoting effect of Fe in Ni/GDC was stabilized via co-deposition with Au and there is for the first-time comparison among the transition metal modifications of Mo-Au-Ni vs Fe-Au-Ni. A series of samples was prepared, where the content of Au varied between 1 and 3 wt.% and between 0.4 and 1 wt.% for Mo. Physicochemical characterization took place with XRF, BET, SEM, H2-TPR, TPH2O and in-situ H2O-XPS. The effect of the transition metals interaction on the performance of SoA Ni/GDC was investigated via electrochemical I-V and EIS measurements in rSOC operation, by applying different pH2O/pH2 mixtures in the temperature range of 900 – 800 oC. It was found that high Mo and/or Au wt.% content, results in larger Mo-Au-Ni particles and affects differently the bulk and surface interaction of the samples with H2O, as well as the Rohm
and Rpol
values of the fuel electrodes. The modified samples were less prone to bulk oxidation by H2O, while they exhibited higher surface oxidation of Ni and higher amount of Ce3+, compared to Ni/GDC. On the surface of the optimum 0.4wt.% Mo-1wt.%Au-Ni/GDC: (i) Ni was less oxidized, (ii) Au0 enrichment was more stable and (iii) Mo was more oxidized, overall affecting positively the Rpol
versus the electrode with the higher loadings of 1 wt.% Mo-3 wt.% Au. The main degradation factor of the latter cell was ascribed to the increased Rohm
. Finally, a new ternary 0.5 wt.% Fe-3 wt.% Au-Ni/GDC electrode is presented, which exhibited superior electrochemical rSOC performance and stability, compared to the optimum Mo-Au-Ni/GDC, highlighting the need for further research in the transition metals effect on SOCs.
Overpotential Behavior of Electrolysis and Fuel Cell Modes of Molten Carbonate Cells
Authors: Lee ChoongGon , Koomson Samuel
Published: February 2024

Molten carbonate is an high operating temperature electrolyte for the fuel cell (MCFC) and electrolysis cells (MCEC). In particular, the liquid molten carbonates allow the reversible operation between fuel cell and electrolysis cells. The electrode kinetics and mass transfer characteristics of MCFC have been rather extensively investigated compared with those of MCEC. In this work, the mass transfer behaviors between MCFC and MCEC have been focused by experimental way with 100 cm2 class bench cells.

The electrodes and matrix in the cell were supplied by KIST in Korea. The cells were operated at 923K under atmospheric pressure. The hydrogen electrode was supplied by a mixture of H2:CO2=1:1, 2:1, 1:2 ratios at 20% or 40% H2O. The oxygen electrode was fed by Air:CO2=0.7:0.3 atm. The steady state polarization (SSP) from 0 to 150 mA cm-2, inert gas step addition (ISA), and reactant gas addition (RA) methods were employed. The ISA adds inert gas to the hydrogen or oxygen electrodes, then the addition varies reactants flow rate and partial pressures. Consequently, the variations are reflected to the cell voltage at open circuit and polarization states. The voltage shift by the flow and partial pressure change represents overpotential behaviors at the electrodes [1]. The RA method uses a reactant gas instead of inert gas in the ISA. Therefore, the RA provides the overpotential information of the added reactant species [2].

From the experimental investigations, the total voltage loss at the FC is larger than that of EC mode. In addition, the hydrogen electrode has significant gas phase mass transfer resistance due to the H2, CO2, and H2O species at the FC and EC modes. A similar overpotential was observed at the hydrogen electrode. On the other hand, the oxygen electrode has much less overpotential at the EC mode than the FC mode. Since the oxygen reduction at the FC mode contains O2 dissolution and mass transfer through the carbonate electrolytes, liquid phase mass transfer resistance is dominant. However, the oxidation of carbonate ions to oxygen does not contain liquid phase mass transfer process at the EC mode. Therefore, much less overpotential was observed at the oxygen electrode at the EC mode than the FC mode. This can be a reason of smaller total voltage loss at the MCEC than the MCFC.

[1] Samuel Koomson, Choong-Gon Lee, J. Electroanalytical Chemistry, 925, 116896 (2022).

[2] C.-G. Lee, H.-C. Lim, J. Electrochem. Soc., 152, A219-A228 (2005).
(Invited) The Liquid Sunlight Alliance: Solar-to-Chemical Energy Using Systems of Catalytic Microenvironments
Authors: Houle Frances , Atwater Harry A.
Published: February 2024

The Liquid Sunlight Alliance’s science program is focused on codesigning systems that convert CO2 into useful fuels with high efficiency, selectivity and durability using sunlight as its sole source of energy. The function of the (photo)electrocatalytic reaction center is inextricably tied to the center’s connections to its surroundings, which govern the availability of reactants and charge carriers, and the removal of desired products. The intrinsic scale of these connections defines the catalytic microenvironment. This talk will describe our current understanding of key aspects of this microenvironment, with a specific focus on how both the catalyst nanostructure and the presence of liquid and solid electrolytes control the availability of dissolved anions, cations, water and CO2.
Diffusion-Restricted Cation Exchange Derived Rhodium Nanoparticles for Hydrazine Assisted Hydrogen Production
Authors: Lee Hak Hyeon , CHOI JI Hoon , Kim Dong Su , Cho Hyung Koun
Published: February 2024

Water splitting using renewable energy is a promising hydrogen production method without carbon emission. However, oxygen evolution reaction still suffers from its large overpotential and sluggish kinetics. Thus, alternative oxidation reactions rather than oxygen evolution reaction, such as ammonia, alcohols and hydrazine oxidation reaction are developed for hydrogen production. Rh is one of the most promising catalysts for electrochemical hydrazine splitting that can promote hydrogen evolution reaction on the cathode, which is a much more energy-saving way to generate hydrogen gas than water splitting. Unfortunately, Rh is also one of the most expensive novel metals on the market. Nevertheless, only a few studies have considered the amount of used Rh. In this study, the diffusion-restricted cation exchange (CE) process is suggested as an effective method to reduce the mass of inactive Rh for enhanced mass activity. By immersing the NiOOH substrate in the Rh3+ aqueous solution, Rh3+ atoms are easily exchanged with Ni3+ atoms in the NiOOH lattice on the surface, and the RhOOH forms on the outermost layer. Then, the RhOOH compounds are reduced into metallic rhodium by an electrochemical reduction process, resulting in fine Rh nanoparticles smaller than 2 nm. Due to the suppression of Rh aggregation, a doubled mass activity for electrocatalytic hydrazine oxidation reaction is attained compared to that of conventional electrodeposited Rh catalysts. As a result, the proposed CE-derived Rh catalyst shows stability over 36 hours under the two-electrode hydrazine splitting system.
Polymeric Anion Exchange Membranes for Green Hydrogen Production
Authors: Roggi Andrea , Martinelli Elisa
Published: February 2024

Producing green hydrogen by using anion exchange membrane (AEM) water electrolysis is a promising approach to address the severe climate and energy crisis facing human society and aid the transition to net-zero emissions. AEM electrolysis can be integrated with renewable energy sources and utilizes cost-effective (Pt-free) electrocatalysts and other inexpensive components in stacks. To enable commercially viable hydrogen generation, improvement of the AEM component is imperative, and the goal of fabricating a membrane, in which the chemical, mechanical and electrochemical requirements are combined and optimized in a synergistic way, still represents a challenging task.The present work was, therefore, aimed at addressing several unique features of AEMs for implementation in an industrially scalable and sustainable energy-production process through a suitable synthetic strategy that involves the post-modification of a commercially available and relatively cheap poly(styrene-b-butadiene) (SB)-based block copolymer matrix by grafting vinylbenzyl chloride (VBC). The synthesized SB-g-VBC copolymers were, therefore, used for the fabrication of AEMs by solution casting followed by quaternization reaction with trimethylamine (TMA) for the quantitative conversion of –CH2Cl into –CH2(CH3)3N+ groups. Obtained AEMs were thermally, mechanically and electrochemically characterized. By varying the VBC functionalization degree of the copolymers it was possible to modulate the ionic exchange capacity, conductivity, water uptake and mechanical properties of the membranes derived therefrom. The most promising AEMs were selected for testing in electrolytic cells (Figure 1) and were found to resist to real operating conditions for more than 40 days.

Acknowledgements. The authors thank the company Enapter s.r.l. for the contribution to the electrochemical characterization and the financial support.

Figure.1 Polarization curves of the SB-g-VBC based AEM as a function of residence time in an electrolytic cell (KOH 1 wt % at 55 °C).

Figure 1
Metal−Organic Framework CPO-27 Derivatives As Non-Precious Metal Catalyst for Anion Exchange Membrane Fuel Cell
Authors: Pradesar Yusuf , Yusuf Afandi , Kabtamu Daniel Manaye , Wang Chen-Hao , Huang Hsin-Chih
Published: February 2024

Fuel cell stands as an environmentally friendly technology harnessing the power of hydrogen to generate clean water. In the range of fuel cell types, the anion exchange membrane fuel cell (AEMFC) stands out, effectively converting chemical energy to electricity without relying on platinum catalyst. Nonetheless, platinum catalyst is still used in addressing the sluggishness of the oxygen reduction reaction (ORR) during AEMFC operation. The scarcity and expense of platinum, however, hinder its widespread adoption. Furthermore, in the alkaline environment, platinum surface is covered with OH species, impeding active sites and diminishing electrochemical activity. Consequently, seeking an efficient, stable, and abundant platinum substitute is a primary target in the development of fuel cell.

This study focuses on the development of the non-precious metal catalyst for the ORR in AEMFC. The catalyst, denoted as NiCo2-CPO-27/PCN, is derived from a carbon nanorod structure obtained from the metal-organic framework (CPO-27). Through the optimized process, the catalyst demonstrates the distinct carbon nanorod configuration. Additionally, the NiCo2-CPO-27/PCN catalyst exhibits enhanced ORR activity, achieving the electron transfer number of 3.99, which closely approaches the ideal four-electron transfer number. This improvement in activity is attributed to factors such as the specific structure, heteroatom contribution, and coordination arrangement of the catalyst.
Active Electrochemical Catalysts for Ammonia and Hydrogen Evolution Reaction
Authors: Wang Di-Yan
Published: February 2024

An environmentally friendly alternative synthesis process is desired to produce NH3 with no CO2 emissions and low energy demand in a sustainable and ecological way in the future. The electrochemical method assisted by earth-abundant materials has been widely utilized for the chemical energy conversion. We have developed new earth-abundant layered structure metal sulfide based materials as active catalysts for electrochemically nitrogen reduction reaction. From electrochemical analysis, the Faraday efficiency of MoS2 and FeS2 for NRR can be achieve to~27% and 14% with good catalytic stability, respectively. The energy profile of the NRR reaction pathway on the catalysts will be performed by the density functional theoretical (DFT) calculation. Besides, there have been lots of studies on hydrogen evolution reaction (HER) catalytic activity using ultralow loading of Pt catalysts or even Pt single atom catalysts as well. However, Pt single atom deposited on the surface of the carbon or metal oxide material showed some drawbacks, such as high possibility of Pt desorption from the supported material in the electrolyte. Our work demonstrated that gold nanodendrites (Au NDs) with high facet surface was chosen as the supported materials for studying the relation between the low loading amount of Pt atoms and reaction mechanism of HER activity. Overall results provides a feasible approach to morphological control of metal sulfide and atomic deposition of Pt element on the specific substrate as active catalysts for NRR and HER applications, respectively.
Rapid Fabrication of Efficient and Stable Microporous Electrodes for Practical Alkaline Water Electrolysis
Authors: Jiang Xinge , Costil Sophie , Kyriakou Vasileios , Liu Taikai , Jiang Tao , Liao Hanlin
Published: February 2024

Efficient and stable electrode is paramount for advancing practical alkaline water electrolysis (AWE) technology. In this study, we employed a rapid and scalable laser texturing process to create microporous nickel electrodes, demonstrating promising catalytic performances for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The alkaline electrolyzer cell (AEL) incorporating laser-textured electrodes (NP-LT30) exhibited a remarkable improvement, with voltage drops exceeding 300 mV under a current density of 1 A cm−1, compared to conventional perforated Ni plate electrodes (NP) based cell. This enhancement resulted from a substantial boost in mass transport, as unveiled by in-situ electrochemical impedance analysis. Of particular note is the unique multi-channel porous structure within the NP-LT30 electrode, enabling rapid mass transport through an innovative convection mode driven by an intermittent bubble eruption (IBE) mechanism, outperforming the traditional convection mode. Furthermore, AEL using NP-LT30 electrodes demonstrated exceptional durability, maintaining performance at 1.0 A cm–2 for an impressive 300 hours. This study highlights the capability of the multi-channel structure within NP-LT30 electrodes to expedite mass transport in practical AWE applications significantly. Moreover, the cost-effective and scalable nature of laser-textured porous electrodes positions them for commercialization, enabling the production of highly efficient electrodes for practical AWE implementation.
Long Term Evolution of MEA for AEM
Authors: Dokhani Sepanta , Khataee Amirreza , Lundblad Anders , Lindbergh Goran
Published: February 2024

Green hydrogen technology, aimed at revolutionizing clean hydrogen production, has recently garnered significant attention. However, the pursuit of cost-effective methods for obtaining clean hydrogen remains a substantial challenge for various industries. Anion exchange membrane water electrolysis (AEMWE) has emerged as a promising solution, leveraging low-cost materials and high efficiency, thus attracting extensive interest from both researchers and industries. Yet, the adoption of AEMWE faces two major hurdles: its relative immaturity as a technology and the limited exploration of its durability and stability. Within the Production, Use, and Storage of Hydrogen (PUSH) Research Center, a collaborative effort involving Chalmers Technical University, Lund University, Umeå University, and Research Institutes of Sweden (RISE), we are dedicated to addressing the scientific and technical barriers currently hindering the seamless integration of hydrogen into sustainable energy systems. Our comprehensive research strategy encompasses every facet of hydrogen, including production, storage, distribution, and utilization, all working synergistically in harmony. One of the ongoing projects in this research center, conducted in cooperation with RISE, around enhancing the durability of components and devices through advanced testing techniques applied to AEMWE. This study present the results of a 2000-hour lifetime test and Accelerated Stress Testing (AST) conducted on a commercial Membrane Electrode Assembly (MEA), showcasing the system's remarkable stability. It must be mentioned that in the next step, these results will be compared with lifetime test and AST from MEAs from other partners within PUSH Research Center.
Growth of Medium-Sized InP Quantum Dots with High Photoluminescence Efficiency and Enhanced Stability
Authors: Yi-Jui Ho , Cheng-Yang Chen , Chen Hsueh-Shih
Published: February 2024

This study introduces medium-sized core/shell InP quantum dots (QDs) with high photoluminescence (PL) efficiency and remarkable material stability. The incorporation of a ZnSe interlayer between the core and the thicker outer ZnS shell enhances both the optical performance and material stability. When further increasing the S/Se ratio to synthesize larger QDs with a thicker ZnS layer, optical performance significantly declines despite the improvement in stability. To achieve QDs with superior optical performance and stability, we controlled the S/Se ratio variation during shell growth and examined its impact on the structure, morphology, and size of InP QDs. Our approach resulted in medium-sized InP/ZnSe/ZnS QDs with tunable wavelengths (606-630 nm), PL quantum yields (PLQY) > 90%, full width at half maximum (FWHM) values < 40 nm, and enhanced material stability.

Keywords: indium phosphide (InP), quantum dots (QDs), high efficiency and stability, S/Se ratio of shell, medium-size quantum dots, stainless steel reactor

Figure 1
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
(Invited) Exploring Electrochemical Deep Reduction for Accessing New Chemical Space
Authors: Lennox Alastair J. J.
Published: February 2024

The definition of electrochemical deep reduction will be discussed and then defined, and our recent research efforts into the use of these potentials will be presented. Specifically, we have initiated a programme of research in electrochemical reductive defluorination of C-F bonds. From this research we show how it is possible to take the relatively inert trifluoromethyl functional group and derivatise it into more valuable building block compounds. I will discuss how this is performed, and what we have achieved to date in this area.
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

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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