bluuebunny/crossref_metadata_2025 huggingface dataset:
Unveiling the Inner Workings of Lithium-Sulfur Pouch Cells: A Multimodal Operando Analysis Approach
Authors: Müller Rafael , Risse Sebastian , Hilger Andre , Kardjilov Nikolay , Boenke Tom
Published: February 2024

This presentation will discuss the use of multimodal operando analysis to investigate the complex processes occurring within lithium-sulfur (Li-S) batteries during charge and discharge cycles. Li-S batteries have attracted significant attention due to their high theoretical energy density, but their practical use has been hampered by several challenges, such as poor cycling stability and low Coulombic efficiency. By using advanced techniques such as X-ray radiography, electrochemical impedance spectroscopy, force measurement, and temperature mapping, we can gain a deeper understanding of the fundamental mechanisms and degradation pathways that occur within Li-S batteries. The results describe macroscopic effects like wetting, swelling, and heating as well as microscopic phase changes, material depositions and interface properties. We will discuss how this knowledge can be used to develop improved battery materials and electrode architectures, ultimately leading to more efficient and durable Li-S batteries.

Figure 1
In-Situ Scanning Transmission X-Ray Microscopy Studies of MnO2-Based Supercapacitor Electrodes
Authors: Eraky Haytham , Zhang Chunyang , Higgins Drew Higgins , Hitchcock Adam
Published: February 2024

Supercapacitors (SCs) as energy storage devices provide higher energy density than conventional capacitors and higher power density than batteries1. Understanding how charge is efficiently stored in the electrodes or across the electrolyte/electrode interface is key to developing advanced SC electrodes. Scanning transmission x-ray microscopy (STXM) studies2 have been used to investigate MnO2 based supercapacitor electrodes using a novel three-electrode based in-situ flow electrochemical device (Fig. 1)3,
4. Near-edge X-ray absorption fine structure (NEXAFS) spectra of MnO2 films in-situ deposited and subjected to several different electrochemical processes were measured with high spatial resolution at the Mn L3 and O K edges (Fig. 2) at both working electrode (WE) and counter electrode (CE) regions. In this work, the redox state changes associated with pseudocapacitance during charging/discharging processes in a potential window of -0.5 VAu to +0.9 VAu (+0.1 VRHE to +1.5 VRHE) have been investigated. The spectroscopic data and quantitative chemical mapping by in-situ STXM measurements demonstrated that an as-electrodeposited MnO2 film was reduced to both Mn3+ and Mn2+ oxidation states through a reversable Mn4+ ↔ Mn3+/Mn2+ redox reaction. A significant change from a quasi-uniform MnO2 film to a dendritc MnO2 structure was observed during discharging at +1.5 VRHE (Fig. 3, Fig. 4) corresponding to redeposition of Mn2+ dissolved into electrolyte during the reduction process5. In-situ STXM measurements at the CE showed there is deposition of MnO2 during the reduction reaction (charging process) at +0.1 VRHE. Mn L3 features of Mn2+ appeared in the electrolyte region during the reduction process and disappeared during the oxidation process, confirming the dissolution/redeposition mechanism. We have developed a novel and versatile platform for in situ studies of electrochemical processes, including supercapacitors, batteries, and electro-catalysts3,
4.

References

A. G. Olabi, Q. Abbas, A. Al Makky, and M. A. Abdelkareem, Energy,
248 123617 (2022).

K. V. Kaznatcheev, C. Karunakaran, U. D. Lanke, S. G. Urquhart, M. Obst, and A. P. Hitchcock, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,
582 (1), 96-99 (2007).

A. P. Hitchcock, C. Zhang, H. Eraky, L. Shahcheraghi, F. Ismail, and D. Higgins, Microscopy and Microanalysis,
27 (S2), 59-60 (2021).

C. Zhang, N. Mille, H. Eraky, S. Stanescu, S. Swaraj, R. Belkhou, D. Higgins, and A. Hitchcock, (2023).

T.-H. Wu, Y.-Q. Lin, Z. D. Althouse, and N. Liu, ACS Applied Energy Materials,
4 (11), 12267-12274 (2021).

Figure 1
Dynamics of Novel Zinc Ion Electrolytes
Authors: Suarez Sophia , Paterno Domenec , Pranto Tawhid , Ahmed Fariha
Published: February 2024

Zinc ion batteries are a niche alternative for battery applications. Their implementation is however afflicted by several factors, one of which is the need for more efficient electrolytes. Deep eutectic solvent (DES) electrolytes based on ZnCl2salt offer many attributes including, including improved stability and reduced dendrite formation. In this work we will present a molecular level understanding of the ion dynamics in electrolyte mixtures based on ZnCl2 and various co-solvents including organic carbonates and water. Focus is on the ion dynamics as interrogated by 1H NMR spin-lattice relaxation times (T1
) combined with ionic conductivity, viscosity and density measurements. As shown in Figure 1, preliminary T1
results infers multiple ionic coordinated species with varying rates of mobilities that are co-solvent dependent. Additionally, data shows selective interaction sites between the hydrogen bond donors and acceptors, as well as the co-solvents.

Figure 1. 1H T1
for the null and AcN co-solvent mixtures of (a) 1ZnCl2:4EtG and (b) 1ChCl:1ZnCl2:6EtG.

Figure 1
Ionic Liquid - Glyme Mixtures to Modify Solvation Chemistry, Electrochemical and Physiochemical Properties in Lithium Containing Electrolytes
Authors: Biddinger Elizabeth J. , Keating Michael , Bernard Elijah , Lall-Ramnarine Sharon , Messinger Robert J.
Published: February 2024

Pyrrolidinium-based ionic liquids are an intriguing material for lithium-based battery electrolytes due to their inherit non-flammability and large electrochemical windows. Poor lithium-ion transport in ionic liquid-based electrolytes hinder the effectiveness of these electrolytes. Solvate ionic liquids were introduced as a subclass of ionic liquids consisting of high concentrations of lithium salts and glymes. For example, the solvate ionic liquid Li(G4)TFSI is an equimolar ratio of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and tetraethylene glycol dimethyl ether (G4). In this work, pyrrolidinium-based ionic liquids containing short polyether side chains, structurally analogous to glymes, are mixed with equimolar amounts of LiTFSI and varying portions of G4. These tertiary mixtures were evaluated based on the ratio of solvating oxygen to lithium ion ([O]/[Li+]) present in the mixture. Trends in the oxidative stability, conductivity and lithium transference number were evaluated from mixtures of [O]/[Li+] between 5 to 8. Oxidative stability of tertiary mixtures with [O]/[Li+] = 5 showed improved oxidative stability compared to the binary Li(G4)TFSI, while [O]/[Li+] > 5 had diminished oxidative stability. DSC thermal analysis between -85°C to +120°C showed the tertiary mixtures helped suppress the glass transition temperature of Li(G4)TFSI to lower temperatures. Changes in the solvation structures were evaluate using spectroscopic analysis, including Raman spectroscopy. The changes in the solvation chemistry were correlated to the physiochemical and electrochemical properties.
Anomalous Increase in Double Layer Capacitance in Ionic Liquid-Metal Salt Blends
Authors: McAlpine Jack , Tupkar Hrishikesh , Gebbie Matthew A.
Published: February 2024

Supercapacitors provide exiting opportunities for the future of energy storage due to a combination of fast charge-discharge kinetics, high safety, and long device lifetimes. Yet, current supercapacitors have energy densities that are orders of magnitude lower than those of lithium-ion batteries, relegating them to niche uses such as regenerative braking systems. While ionic liquids have shown promise as next generation electrolytes in supercapacitors due to their nonflammable nature, large electrochemical stability window, and predicted large capacitances, neat ionic liquids have capacitances ranging from 5 to 20 µFcm-2 which does not compete with current supercapacitors made with cheaper electrolytes. In this talk, I will discuss how we have substantially increased the capacitance of ionic liquid-electrode interfaces though the addition of metal salt additives containing Li, Na, K, and Mg ions. We maintain the large voltage window while increasing the capacitance to up to 80 µFcm-2 at both positive and negative polarizations of gold electrodes. By conducting complementary surface structuring studies, we elucidate molecular assembly at charged surfaces to understand ion behavior when only surrounded by other ions in solution. We hypothesize that the introduction of metal salts interrupts ion aggregates that exist in concentrated electrolytes, reducing the screening lengths in ionic liquids and thus increasing capacitance. Overall, our study demonstrates that ionic liquids may have transformative promise for next-generation supercapacitors, and highlights new paradigms for tuning interfacial properties via modulation of ion coordination in concentrated electrolytes.
Electrochemical Behavior of Tris(2,2'-bipyridine)Iron Complex in 1-Butyl-1-Methylpyrrolidinium Bis(fluorosulfonyl)Amide Ionic Liquid in the Presence and Absence of Lithium Ion
Authors: Katayama Yasushi , Kato Shodai , Serizawa Nobuyuki
Published: February 2024

Ionic liquids composed of bis(fluorosulfonyl)amide (FSA–) have been investigated as the promising electrolytes for rechargeable batteries because of the formation of favorable solid electrolyte interphase (SEI) for some alkali metal ions in addition to relatively low viscosity. The FSA–-based ionic liquids are also considered to be applied to redox flow batteries, which utilize the electrode reactions of soluble species on inert electrodes. However, few electrode reactions of dissolved species have been explored in the FSA–-based ionic liquids. On the other hand, ion-conductive membranes are necessary for development of redox flow batteries. An inorganic solid-state conductor, lithium ion conductive glass ceramics (LICGC, Li1+x+y
Al
x
(Ti,Ge)2-x
Si
y
P3-y
O12), is one of the possible membranes usable in ionic liquids containing Li+. In the present study, the electrochemical behavior of tris(2,2'-bipyridine)iron complexes, [Fe(bpy)3]2+, was investigated in BMPFSA (BMP = 1-butyl-1-methylpyrrolidinium) in the presence and absence of Li+.

The redox reactions of [Fe(bpy)3]3+/2+, [Fe(bpy)3]2+/+, [Fe(bpy)3]+/0, and [Fe(bpy)3]0/– were observed by cyclic voltammetry in the absence of Li+. However, these reactions were affected by the SEI formation at a negative potential region in the presence of Li+. The donor number of BMPFSA was estimated from the formal potential of [Fe(bpy)3]3+/2+. The diffusion coefficients of [Fe(bpy)3]3+ and [Fe(bpy)3]2+ were determined by chronoamperometry. The standard rate constant for [Fe(bpy)3]3+/2+ was evaluated by electrochemical impedance spectroscopy. The relationship between these kinetic parameters and physical properties was discussed.
(Invited) Unravelling the Core of Fuel Cell Performance: Engineering the Electrolyte (ionomer)/Catalyst Interface
Authors: Xie Jian
Published: February 2024

The biggest challenge of the widespread implantation of the polymer electrolyte membrane fuel cells (PEMFCs) is the cost, primarily due to the use of platinum catalysts. The high intrinsic catalyst activity exhibited using a rotating disc electrode (RDE) is rarely realized in the membrane electrode assembly (MEA), which is the core of PEMFC, due to the difference on the electrolyte(ionomer)/catalyst interfaces. To translate the catalyst RDE performance into MEA, the design of an ideal ionomer/catalyst interface is proposed: a thin, conformal ionomer film covers the maximum surface of a Pt nanoparticle that simultaneously maximizes catalyst utilization, (i.e. high mass activity and electrochemical active surface area) and O2 diffusion (i.e. high current density performance) without compromising proton conduction. Building such an interface is a long-standing challenge due to no control of ionomer distribution over catalyst particle, resulting in large ionomer agglomerates and inhomogeneous ionomer coverage over the catalyst nanoparticle, consequently, poor fuel cell performance. In this work, this ionomer/catalyst interface has been constructed utilizing the electrostatic charge attraction between positively charged catalyst and negatively charged ionomer particles in a liquid and preserved into a solid catalyst layer. Consequently, this interface leads to the previously unachieved fuel cell performance on both the catalyst utilization (75% vs. 45%) and the rated/peak power density (Pt/C, 0.910/1.430 W/cm2 for H2/Air, Pt loading: 0.1 mgPt/cm2), matching that of Pt alloy catalysts. This work demonstrated the formation of the interface in the liquid phase (using ultra-small angle x-ray scattering in combination with cryo-TEM, isothermal‐titration‐calorimetry) and the preserved interface in the solid catalyst layer (using TEM) and estimated the effective coverage and thickness of the ionomer film (using the limiting current density, RDE and fuel cell performance).
(Invited) Electrochemical Characterization of Catalyst/Ionomer Interfaces
Authors: Kusoglu Ahmet
Published: February 2024

Electrochemical energy conversion devices such as polymer-electrolyte fuel cells, water-splitting or carbon dioxide reduction electrolyzers, utilize ionically-conductive polymers (ionomers) in their electrode structure where an ionomer forms interfaces with the catalysts. The ionomers exist as nanometer-thick film to cover the catalyst particles and act as a binder while enabling the transport of active species necessary for the reactions. While the nature of species and operational environment differs across these devices, their overall efficiency and performance is influenced by the electrode architecture, where the interfaces and interactions between the ionomers and catalysts play an important role. In hydrogen technologies, for example, ionomer thin films bind the catalyst sites and carbon supports to facilitate transport of ionic (e.g. protons), liquid (water) and gaseous (e.g., oxygen) species under a nano-confined environment. Such confinement effects not only change the ionomer structure and properties, usually with a tendency to increase transport resistances, but also amplify the impact of the electrocatalyst-ionomer interactions in the electrodes, thereby reducing the catalyst activity. Thus, understanding the behavior of nano-confined ionomers and their interactions with the catalyst surfaces is key for mitigating the transport resistances in catalyst ionomers and improving the electrode performance and cell efficiency.This talk will provide insights into electrochemical characterization of catalyst ionomers by focusing on varying chemistries of perfluorosulfonated cation-exchange ionomers with additional examples of anion-exchange ionomers for emerging technologies. The hydration and transport properties of proton-exchange catalyst-ionomers will be examined with the effects of chemistry, processing and thickness (degree of confinement), along with their impact on the morphological changes governing the film function. Through a systematic variation of material chemistries and environmental parameters, primary factors impacting the structure-property relationship of catalyst ionomers are described along with a discussion of secondary factors altering the cation-anion interactions. Then, the interplay between the effects of chemistry and ion exchange (capacity) on modifying the transport function and the strength of ionomer-catalyst interactions will be presented. The results will be collated to elucidate the underlying origins of the transport resistances occurring in electrodes, and to develop materials and processing strategies for their mitigation for improved performance and efficiency in electrochemical energy devices.
(Invited) Durable Hybrid Electrocatalysts for Fuel Cells
Authors: Shao Minhua , Xiao Fei
Published: February 2024

Proton exchange membrane fuel cell converts hydrogen and oxygen into electricity with zero emission. The high cost and low durability of Pt-based electrocatalysts for oxygen reduction reaction hinder its wide applications. The development of non-precious metal electrocatalysts also reaches the bottleneck because of the low activity and durability. Here we rationally design a hybrid electrocatalyst consisting of atomically dispersed Pt and Fe single atoms and Pt-Fe alloy nanoparticles. The Pt mass activity of the hybrid catalyst is 3.7 times higher than that of commercial Pt/C in a fuel cell. More importantly, the fuel cell with an ultra-low Pt loading in the cathode (0.015 mgPt cm-2) shows excellent durability, with 97 % activity retention after 100,000 cycles and no noticeable current drop at 0.6 V for over 200 h. These results highlight the importance of the synergistic effects among active sites in hybrid electrocatalysts and provide an alternative way to design more active and durable low-Pt electrocatalysts for electrochemical devices.
(Invited) Nanomembrane Coating for Advanced Electrocatalysis
Authors: Takanabe Kazuhiro
Published: February 2024

Advanced electrocatalysis that possesses higher selectivity and durability is more and more important for the electrification of chemical processes, which is expected in the renewable energy society in the future. Electrochemical reactions are often determined by the competition between the thermodynamic redox potential and the applied potential. Because the redox potential is characteristic for determining the product, it is often difficult to adjust the selectivity just by surface chemistry. Against this background, surface modification of electrodes is a well-studied field. Surface modification improves membrane functionality and selectivity, resulting in electrocatalysts with higher productivity and selectivity. Surface protective layers are also associated with material durability, as they prevent toxic and harmful substances from approaching the surface and prevent dissolution of the electrode material into the electrolyte. We are investigating the use of "nanomembrane" coatings on electrodes to achieve better selectivity and durability.

Electrochemical reduction deposition of ultrathin layers of Cr and Mo on Pt cathodes has been shown to yield O2-tolerant hydrogen-evolving electrodes in the appropriate pH range. Electrochemical measurements indicate that these surface layers act as a membrane film. Many bulky ions and O2 molecules cannot pass through these surface layers, but H2 molecules can, consistent with electrochemical and spectroscopic measurements. First, the electrochemical properties of Pt modified with other elements such as Cr and Mo were investigated and monitored for catalytic activity under different atmospheres. Next, in-operando X-ray absorption spectroscopy (XAS) was used to investigate the working state of the material: electrochemical measurements in H2 and O2 confirmed that the oxygen reduction reaction (ORR) was severely suppressed and the hydrogen evolution reaction (HER) was maintained. XAS results also showed that the oxidation state of Pt can be freely changed by a potential sweep with or without a coating layer. We extended this work to nanofilm coating on oxygen-evolving anodes for water splitting, and succeeded in anodic deposition of a thin Ce layer on Ni-Fe electrodes; the Ce layer not only prevents unwanted ions from reaching the electrode surfaces, but also prevents Fe ions from leaching from the electrodes, thus improving the durability of the electrodes. In this presentation, key findings of these nanomembrane coatings and future prospects for selective and durable electrodes will be discussed.
(Invited) Designing Advanced Low-PGM Core-Shell Electrocatalysts for Fuel Cells and Electrolyzers
Authors: Sasaki Kotaro , Zhao Xueru
Published: February 2024

The low-content Pt-based core-shell catalysts potentially alleviate the drawback in the existing Pt catalysts (i.e., high cost, slow kinetics, poor stability, etc.) and further improve the oxygen reduction reaction (ORR) activity and stability for the proton exchange membrane fuel cells (PEMFCs).1 There have been remarkable advances in both the development of promising core−shell catalysts and the understanding of the fundamental catalytic mechanisms, and it is clear that some of the low platinum-group-metal (PGM) core−shell catalysts with enhanced activity and stability have great potential for use in PEMFCs. Nevertheless, various issues still need to be clearly addressed for the advanced core−shell catalysts of the future. On the other hand, PEM electrolyzers (ELs) are desirable large-scale energy devices to produce green hydrogen toward a net-zero carbon economy. The technologies require the availability of effective catalysts, particularly for the oxygen evolution reaction (OER). However, Ir- and Ru-based catalysts are currently the best-performing OER catalysts and their cost and limited availability hamper the widespread commercialization/deployment of PEMELs. Therefore, there is also an urgent need for developing highly durable and inexpensive catalysts for the OER. This talk first focuses on synthetic strategies, catalytic mechanisms, and influencing factors of Pt- and Ir-based catalysts used for PEMFCs and PEMELs. We will then discuss effective and solid strategies/designs to employ transition-metal-nitride-based cores for the development of highly advanced low-PGM core-shell catalysts for the ORR, particularly in heavy-duty vehicle (HDV) PEMFC applications, and for the OER in PEMEL applications.

R. Zhao and K. Sasaki, Advanced Pt-Based Core-Shell Electrocatalysts for Fuel Cell Cathodes, Accounts of Chemical Research.
55 (2022) 1226-1236.
Disentangling pH Effects on Electrocatalytic Reactions
Authors: Eikerling Michael , Zhu Xinwei , Huang Jun
Published: February 2024

Electrocatalysis is the key discipline to enable breakthrough advances in electrochemical energy technology and in the conversion of CO2 into renewable fuels and value-added chemicals. However, crucial electrocatalytic reactions are afflicted with sluggish kinetics and low selectivity. The electrolyte plays a vital role for the course of an electrocatalytic reactions and, in this realm, understanding the impact of the local pH is crucial for electrocatalyst development and design. The high interest in this topic in the research community is well-reflected in the recent literature, cf., e.g., Science
2022, 375 (6579). Explanations of pH effects remain controversial, even for the simplest model reactions, i.e., the hydrogen evolution/oxidation reaction and the formic acid oxidation reaction (FAOR), since a complex interplay of multiple interacting factors, centered around the local reaction environment and kinetic effects, must be disentangled. Theory and modeling are indispensable in this context. We will present a hierarchical framework that self-consistently couples the impacts of the microkinetics, mass transport and double layer charging effects (going beyond Frumkin corrections).1,2 In our modelling work, we will assess the role of distinct phenomena and parameters at play in a step-by-step fashion. The developed framework will be demonstrated for the FAOR and other electrocatalytic reactions.

References

[1] X. Zhuet al. (2021). ACS Catalysis
11, 14521-14532.

[2] X. Zhu et al. (2023). JACS Au XXXX, XXX, XXX−XXX.

Figure 1
Nanoengineered Bifunctional Porous Ni5P4 Electrocatalyst with Accelerated Bubble Departure and Reduced Overpotential for Solar-Driven Water Splitting
Authors: Lalwani Shubra , Lu Xinnan , Yuan Lin , Abbas Abdelsalam Mohamed , Zhang TieJun , Lalwani Shubra
Published: February 2024

To achieve the global "carbon neutral" goal and low-carbon economy by 2050-2100, hydrogen has been considered as an ideal renewable and sustainable energy carrier.1,2 The electrochemical conversion of solar energy to energy dense hydrogen fuel ensures a promising approach to generate a clean and sustainable source of energy.3,4 The integrated solar powered water electrolyzers for green hydrogen production completely eliminate all sources of carbon emissions arising from the direct power supply, towards achieving a low-carbon economy.5,6 However, large-scale solar water splitting for green hydrogen production still remains a challenge due to expensive electrocatalyst. As a low-cost, earth-abundant catalyst Nickel phosphide shows enormous potential to effectively reduce water and generate hydrogen. We propose a low-cost and facile approach to fabricate nanoengineered hierarchically porous Ni5P4 as an electrocatalyst (p-Ni5P4) providing high surface area and enabling fast gas diffusion. Nickel phosphide (p-Ni5P4@NF) has pores ranging from 50-500 nm to 200-600 μm and enlarges the electrochemically-active surface area by 5 times. The porous structure of p-Ni5P4@NF offers abundant cavities to gas nucleation and fast growth of H2 bubble, and small bubbles (10-50 µm) depart quickly owing to reduced contact line. By enhancing gas transfer and reducing bubble overpotential by 30%, p-Ni5P4@NF achieves excellent electrocatalytic performance with a low HER (145 mV), OER (197 mV) and overall water splitting potential (1.54 V) at 10 mA cm-2. Powered by multijunction PV cell, the full electrolytic cell records a high solar-to-hydrogen efficiency of 14.5 %.

Keywords: Water splitting; Electrocatalysis; Green Hydrogen; Nickel Phosphide.

References

1. Agreement P. Paris agreement. Report of the Conference of the Parties to the United Nations Framework Convention on Climate Change. 2017, Retrieved December. 4.

2. Britain, G. Our energy future: creating a low carbon economy. Stationery Office. 2003.

3. Dunn, S. Hydrogen futures: toward a sustainable energy system. J. Hydrog. Energy 2002, 27, 235-264.

4. Turner, J. A. Sustainable hydrogen production. Science 2004, 305, 972-974.

5. Zeng, M.; Li, Y. Recent advances in heterogeneous electrocatalysts for the hydrogen evolution reaction. Mater. Chem. 2015, 3, 14942-14962.

6. Han, Y.; Chen, Y.; Fan, R.; Li, Z.; and Zou, Z. Promotion effect of metal phosphides towards electrocatalytic and photocatalytic water splitting. EcoMat. 2021, 3, e12097.
Operando X-Ray Absorption Spectroscopy of Solid Electrolyte Interphase Formation on Silicon Anodes
Authors: Swallow Jack E. N. , Fraser Michael , Kneusels Nis-Julian , Charlton Jodie F. , Sole Christopher G. , Phelan Conor , Björklund Erik , Bencok Peter , Escudero Carlos , Pérez-Dieste Virginia , Grey Clare P. , Nicholls Rebecca J. , Weatherup Robert S.
Published: February 2024

Lithium-ion batteries (LIBs) are key to the transition from fossil fuels towards increased use of renewable energy sources. However, more widespread deployment requires improvements in energy density, cost and cycle-lifetime. Various cathode and anode materials are under consideration for next-generation LIBs, and the interfacial stability of these materials in contact with the electrolyte is a critical consideration. Interface-sensitive operando characterization techniques are thus urgently needed to reveal the reactions occurring in working batteries.1,2

The solid electrolyte interphase (SEI) that forms on Li-ion battery anodes is critical to their long-term performance, however observing SEI formation processes at the buried electrode-electrolyte interface is a significant challenge. Here we show that operando soft X-ray absorption spectroscopy in total electron yield mode can resolve the chemical evolution of the SEI during electrochemical formation in a Li-ion cell, with nm-scale interface sensitivity. O, F, and Si K-edge spectra, acquired as a function of potential, reveal when key reactions occur on high-capacity amorphous Si anodes cycled with and without fluoroethylene carbonate (FEC).3 Cross-referencing to cycling data, complementary bulk sensitive fluoresecent yield (FY) XAS measurements, and density functional theory (DFT) calculated spectra enables identification of the electrolyte and SEI species, and the dominant mechanisms of SEI formation. Without FEC present, LiF formation is detected at 0.6 V vs. Li/Li+ prior to significant lithiation of the a-Si, whilst at lower potentials the SEI grows in thickness with an increased contribution from organic components containing -C(=O)O- species. The observed sequential formation of inorganic and organic components is implicated in layering of the SEI. With FEC as an additive we see the onset of SEI formation at much higher potentials (1.0 V vs. Li/Li+), and attribute the improved cycle life seen with this additive to the rapid healing of SEI defects formed during delithiation. Operando TEY-XAS offers new insights into the formation mechanisms of electrode-electrolyte interphases and their stability for a wide variety of electrode materials and electrolyte formulations.

References

Wu et al. Phys. Chem. Chem. Phys.
2015, 17, 30229.

Weatherup et al. Top. Catal.
2018, 61, 2085.

Swallow et al. Nature Commun.
2022, 13, 6070.
(Invited) First Principles Examination of Multiple Criteria of Organic Solvent Oxidative Stability in Batteries
Authors: Leung Kevin
Published: February 2024

Oxidative instability of the liquid electrolyte at or near battery cathode oxide surfaces has significant detrimental effects on batteries. Organic solvent molecules are often the fuel and precurors of such degradation processes, releasing electrons and protons that react with cathode oxides and electrolyte anions. These reactions contribute to cathode electrolyte interphase (CEI) film formation, transition metal ion dissolution, and phase transformation of the surface regions of the cathode. Here we apply Density Functional Theory calculations to examine four criteria of oxidative stability (oxidation potential, hydrogen removal energies, and initial reactivity on two types of oxide facets) using four different solvent/additive molecules (ethylene carbonate, fluoroethylene carbonate, 1,3-dioxolane, and dimethyl ether). The ranking of molecular stability differs with each criterion. Surprisingly, the all-oxygen terminated basal planes of layered oxides exhibit lower reaction barriers than spinel surface facets with exposed transition metal cations, especially for ether solvents; the calculations also suggest basal planes contribute to the dissolution of transition metal ions. The structure-degradation relation complexity underscores the challenge of understanding the function of the CEI, but also offers a guide to future degradation-mitigation strategies including facet-engineering. Our predictions and models help establish a framework for future studies relevant to high voltage conditions.

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the document do not necessarily represent the views of the U.S. Department of Energy or the United States Government.
(Keynote) Kinetic and Non-Kinetic Limitations during Oxygen Evolution Reaction on Nickel-Iron Oxyhydroxide Electrodes
Authors: Koper Marc
Published: February 2024

The rate and mechanism of the oxygen evolution reaction (OER) depends on many factors. Here, we show on the example of OER on nickel oxy-hydroxide electrodes in alkaline media, how the OER rate depends on pH, cations, nano-catalyst structure, bubble removal, mass transport, temperature and pressure. We illustrate that many of these parameters lead to a higher current (density) but also argue that they often do not actually remove true kinetic barriers. Tafel slope plots or differential Tafel plots are introduced as a powerful tool to separate kinetic from non-kinetic limitations.
Catalytic Active Sites Determination and Charge Transport of Transition Metal Oxides for Oxygen Evolution Reaction
Authors: Song Fang
Published: February 2024

The oxygen evolution reaction (OER) is a key process that enables the storage of renewable energies in the form of chemical fuels.[1] Unraveling the catalytic mechanism is of paramount significance for the rational design of efficient electrocatalysts.[1] Here, we use well-defined crystalline cobalt oxyhydroxides CoOOH nanorods and nanosheets as model catalysts to investigate the geometric catalytic active sites.[2] We disclose a linear correlation of catalytic activities with their lateral surface areas, suggesting that the active sites are exclusively located at lateral facets rather than basal facets. Theoretical calculations show that the coordinatively unsaturated cobalt sites of lateral facets upshift the O 2p-band center closer to the Fermi level, thereby enhancing the covalency of Co-O bonds to yield the reactivity. Following this, we develop a eutectic dealloying strategy to activate the porous spinel NiFe2O4 nanowires with up to four metal cation substitutions.[3] Spinel oxide of NiFeXO4 (X= Fe, Ni, Al, Mo, Co, Cr, ~195 mV@10mA·cm-2) outperforms most spinel phase OER electrocatalysts and comparable to the state-of-the-art NiFe hydroxides. This work elucidates the geometrical catalytic active sites and enlightens the surface engineering for efficient OER catalysts. Besides, we studied the dependence of catalytic performances on electrical conductivities and unveils that charge transportability, to our surprise, regulates the reaction kinetics of the electronically accessible active sites.[4] Remarkably, the regulation extent correlates with the electrical conductivities, suggesting the strong coupling of the electrocatalytic process with electronic transport. Furthermore, we argue the origin of Ov-promoted catalytic activities of NiFe-based (oxy)hydroxides.[5] We uncover the pivotal role of charge transport for their electrocatalytic OER and propose that the superficial Ov imposes electron donation to the conductive band of NiFeOOH and therefore enables the regulation of electronic transport to switch on/off OER catalysis. The work highlights the pivotal role of electronic transportability in unfolding catalytic potential, holding both fundamental and technical implications for electrocatalysts.

Fang Song, ..., and Xile Hu*.
Am. Chem. Soc.
2018, 140, 7748; Fang Song, Xile Hu*.
Nat. Commun.
2014, 5, 4477; Fang Song, Xile Hu*,
J. Am. Chem. Soc.
2014, 136, 16481-16484; Fang Song, ..., Hao Ming Chen,* Clemence Corminboeuf,* Xile Hu *.
ACS Cent. Sci.
2019, 5, 558; Chen, Wenshu; Gu, Jiajun*; Du, Yongping*; Song, Fang*; ...; Zhang, Di.
Adv. Funct. Mater.
2019, 30, 2000551; Bowen Liu, ..., Fang Song,* Qinglei Liu.*
ACS Nano
2022, 16, 9, 14121.

Sihong Wang, Qu Jiang, ..., and Fang Song,*
Commun.
2022, 13, 6650;

Qiwen Zhang, ..., Fang Song*, Mingwei Chen, and Pan Liu*.
ACS Nano
2023, 17, 1485.

Haoyue Zhang,# Lingling Wu,# ..., and Fang Song*., ACS Appl. Mater. Interfaces, In revision.

Haoyue Zhang,# Lingling Wu,# ..., and Fang Song*. ACS Catal. In press.
(Invited) Application of Metal Oxide Active Supports for Enhancement of Electrocatalytic Reduction of Carbon Dioxide
Authors: Rutkowska Iwona A. , Chmielnicka Anna , Siamuk Olena , Sobkowicz Karolina , Rytelewska Beata , Kulesza Pawel J.
Published: February 2024

Of particular interest to the preparation of advanced catalytic materials is efficient utilization of catalytic sites (metal and metal oxide nanostructures, their stabilization and intentional activation, as well as organization into two-dimensional arrays, ultra-thin films or three-dimensional networks (e.g. through sequential deposition) on electrode surfaces. They can form nanosized materials with well-defined composition, structure and thickness that exhibit desirable electrocatalytic properties (e.g. toward reduction of CO2). We explore here the ability of polynuclear inorganic metal oxo systems to stabilize and functionalize metal (e.g. copper) nanostructures. Here certain nanostructured metal oxides of zirconium, titanium, zinc or tungsten have been demonstrated to influence supported metal (e.g. Cu, Fe, Ag) centers in ways other than simple dispersion over electrode area. Evidence is presented that the support can modify activity (presumably electronic nature) of the above mentioned catalytic metal nanocenters thus affecting their chemisorptive and catalytic properties. Metal oxide cocatalysts can generate –OH groups at low potentials that induce proton mobility at the photo(electro)chemical interface.

Our research interests concern development of systems for the electrocatalytic reduction of carbon dioxide not only in neutral but also in acid media. For example, nanosized Cu or Fe catalytic centers immobilized within ultra-thin films of tungsten oxide or mixed ZrO2-WO3 films have been considered and demonstrated to exhibit synergism during CO2-reduction. Selectivity of the catalytic systems largely depends on the activing adsorptive (CO2) phenomena and the affinity of catalytic centers to the adsorbed carbon monoxide (CO) type intermediates leading to their protonation or hydrogenation. Reduction of carbon dioxide begins now at less negative potentials and is accompanied by significant enhancement of the CO2-reduction current densities relative to the competitive hydrogen evolution. Among other important issues is the ability of certain metal oxides (e.g., WO3) to affect hydrogen via intra-structural sorption of hydrogen molecules or atoms.
Exploring the Mechanism of the Electrochemical Polymerization of CO2 over CeO2(110)
Authors: Keller Florian , Döhn Johannes , Gross Axel , Busch Michael
Published: February 2024

The reduction of CO2 is a promising route for the synthesis of renewable energy carriers and the removal of CO2 from the atmosphere to limit global warming. These negative emission technologies (NETs) require the conversion of carbon dioxide into a stable and easily storable form[1]. However, despite its potential, the development of suitable CO2 reduction catalysts is still in its infancy. Indeed state of the art catalysts suffer from high overpotentials, a low selectivity between possible products and a generally low yield of post CO products with two or more carbon atoms. Catalysts which even allow for the electrochemical polymerization of CO2 and thus, the direct formation of hard carbon were completely absent until the work of Esrafilzadeh et al.[2]. Using a liquid electrocatalyst consisting of Ga, In, Sn and Ce in a n,n-dimethylformamide (DMF) electrolyte they were able to polymerize CO2 electrochemically to a carbonaceous material. They hypothesized that the active catalyst consists of a cerium oxide which is reduced to metallic Ce in the process. However, no direct proof for this hypothesis was provided. Also a possible mechanism which could lead to the reported products is so far unknown.

In this contribution we will explore the reaction mechanisms for the electrochemical polymerization of CO2 using density functional theory (DFT) modelling. In the initial step, the most likely active sites at Ce oxide are identified. This is then followed by a detailed analysis of the reaction route which is based on well known mechanisms in organic chemistry. We find that an oxygen defect rich CeO2(110) surface is most likely present under reaction conditions. [3] The reaction over this surface is initialized at oxygen defect sites. Chain propagation is then achieved through an electrochemical aldol condensation type mechanism (Figure 1). [3]

References

1 J. Hilaire, J. C. Minx et al., Climatic Change, 2019, 157, 189.

2 D. Esrafilzadeh, A. Zavabeti et al., Nature. Commun., 2019, 10, 865.

3 F. Keller, J. Döhn, A. Groß, M. Busch, in preparation.

Figure 1
Zn-Based Catalysts for Selective and Stable Electrochemical CO2 Reduction at High Current Densities
Authors: Stamatelos Ilias , Dinh Cao Thang , Lehnert Werner , Pasel Joachim , Shviro Meital
Published: February 2024

The development of low-cost and stable catalysts is important for lowering the capital and operational cost of CO2 electro-reduction (ECR). Zinc (Zn) is an earth-abundant metal, with promising performance for the CO2-to-CO conversion.1 Zinc oxide (ZnO) has been recently employed for the CO2-to-CO conversion, recording promising selectivity (FECO) but short-term stability, in Flow-Cell configuration.2,3 ZnO phase has been proven critical for competent ECR performance, since both the oxidation state of Zn and the Zn/ZnO interface are proven critical for high FECO. 4,5In our work 6, we have synthesised various ZnO allotropes, the properties of which induced differences in their ECR performance. We have identified the ZnO nanorods (ZnO-NR) as the best performing catalyst. The latter was implemented in a zero-gap ECR electrolyser (MEA), recording partial current density for CO (jCO) of 160 mA cm-2 at cell voltage of 3.6 V. We have correlated the depletion of the ZnO phase in the MEA with the degradation of the performance (initially 15 h stability). We applied a periodic oxidation protocol in the MEA, causing the regeneration of ZnO-phase, allowing us to prolong the life-time of the catalyst. Through our strategy we were able to record 82% CO selectivity (FECO) for over 100 h, at -160 mA cm-2. This work provides an approach of practical use of inexpensive Zn-based catalysts for large-scale ECR applications.

(1) Luo, W.; Zhang, J.; Li, M.; Züttel, A. Boosting CO Production in Electrocatalytic CO2 Reduction on Highly Porous Zn Catalysts. ACS Catal.
2019, 9 (5), 3783–3791. https://doi.org/10.1021/acscatal.8b05109.

(2) Zeng, J.; Fontana, M.; Sacco, A.; Sassone, D.; Pirri, C. F. A Study of the Effect of Electrode Composition on the Electrochemical Reduction of CO2. Catalysis Today
2021. https://doi.org/10.1016/j.cattod.2021.07.014.

(3) Zong, X.; Jin, Y.; Li, Y.; Zhang, X.; Zhang, S.; Xie, H.; Zhang, J.; Xiong, Y. Morphology-Controllable ZnO Catalysts Enriched with Oxygen-Vacancies for Boosting CO2 Electroreduction to CO. Journal of CO2 Utilization
2022, 61, 102051. https://doi.org/10.1016/j.jcou.2022.102051.

(4) Nguyen, D. L. T.; Jee, M. S.; Won, D. H.; Jung, H.; Oh, H.-S.; Min, B. K.; Hwang, Y. J. Selective CO2 Reduction on Zinc Electrocatalyst: The Effect of Zinc Oxidation State Induced by Pretreatment Environment. ACS Sustainable Chem. Eng.
2017, 5 (12), 11377–11386. https://doi.org/10.1021/acssuschemeng.7b02460.

(5) Geng, Z.; Kong, X.; Chen, W.; Su, H.; Liu, Y.; Cai, F.; Wang, G.; Zeng, J. Oxygen Vacancies in ZnO Nanosheets Enhance CO2 Electrochemical Reduction to CO. Angewandte Chemie International Edition
2018, 57 (21), 6054–6059. https://doi.org/10.1002/anie.201711255.

(6) Stamatelos, I.; Dinh, C.-T.; Lehnert, W.; Shviro, M. Zn-Based Catalysts for Selective and Stable Electrochemical CO2 Reduction at High Current Densities. ACS Appl. Energy Mater.
2022. https://doi.org/10.1021/acsaem.2c02557.

Figure 1
Understanding Performance Fading during CO Electrolysis in Zero Gap Electrolyzers
Authors: Ayyub Mohd Monis , Serfőző Andrea , Endrődi Balázs , Janaky Csaba
Published: February 2024

Electrochemical CO reduction (ECOR) can act as a potential bridge between CO2-to-CO technologies and renewable production of C2+ chemicals. Copper has been the most widely studied cathode catalyst for ECOR because of its unique ability to produce multicarbon products. Iridium and nickel are the most-widely used anode materials for acidic and alkaline electrolysis, respectively. However, recent reports on the instability of Ir in alkaline conditions and Ni in near neutral conditions has made it imperative to understand the anodic processes for achieving stable long term operation at high current densities for CO2/CO electrolysers.

In this work, our aim was to investigate anode catalysts for ECOR at high current densities in zero gap electrolyser. Commercial Cu nanoparticles (25 nm) was used as the cathode catalysts with Ir black anode in alkaline conditions. Initially, CORR was studied in a hybrid cell with a catalyst coated anion exchange membrane and recirculated catholyte and anolyte. In this cell configuration we observe stable production of ethylene, acetate and ethanol for a total current density of upto 500 mA cm-2. However, in the zero gap electrolyser the catalytic activity decays rapidly (2-3 minutes) and leads to predominance of hydrogen evolution reaction (HER).

Analysis of the cathode and anolyte after electrolysis reveals the dissolution of Ir and subsequent deposition at the cathode. This rapid decay is counter intuitive since the dissolution of Ir in alkaline solutions is very slow and should take a few hours to affect the catalytic activity. More importantly this dissolution of Ir does not happen when Ar is circulated at the cathode instead of CO, which indicates that the Ir dissolution is not entirely due to the alkaline environment. NMR analysis of the anolyte shows the presence of CO reduction products acetate and ethanol. Therefore, it is possible that the presence of CO reduction products could aggravate the Ir dissolution. This study is currently underway to analyse the possible Ir dissolution mechanisms. This is an important observations since Ir is still the most widely used anode catalyst for CO electrolysis. This also stresses on the need to explore alternative anode catalysts and/or design strategies that can circumvent the migration of reduction products to the anode.
Developing a Highly Stable Quaternary Sn-Sb-Mo-W Scaffold to Protect Active Metals for Corrosion during the Oxygen Evolution in Acidic Media
Authors: Piñeiro Alexis , Wu Xiuyu , Rafei Mouna , Mörk Paul Jonathan , Gracia-Espino Eduardo
Published: February 2024

Proton exchange membrane (PEM) water electrolysis powered by renewable energies is seen as one of the most powerful techniques for the high production of ultra-pure hydrogen. However, PEM requires of noble metals as catalysts while operating under harsh acidic conditions, creating a detrimental environment which conducts to fast corrosion of the catalyst. Reducing and extending the lifetime of noble metals under acidic conditions will benefit the hydrogen economy. Currently, one of the major limitations relies on the high corrosion that anode electrocatalysts suffer, where the oxygen evolution reaction (OER) takes place. The best performing electrocatalysts are based on ruthenium (Ru) and iridium (Ir) either in the pure oxide form or as engineered composites, being Ru the most active but less stable even at moderate cell potentials. Here, we investigate the quaternary Sn-Sb-Mo-W mixed oxide (MO) as an effective scaffold to protect RuO2 for corrosion. The acid-stable MO was produced via plasma spraying forming an interconnected network of nanostructured WO3, Sb2O3, SnO2, and MoO3. Low quantities of Ru (2.64% w/w Ru) were stabilized into the matrix (Ru-MO) and finally supported on FTO. The Ru deactivation was described by a second-order reaction with a deactivation rate constant of k = 0.067 cm2 (mA·min)-1. Titanium fiber felt was later used as support (Ru-MO@Ti) where a mass activity of 4440 A g-1
Ru@1.8V(RHE) was obtained, and solely a reduction of 20% was seen in the OER activity after 2000 CVs (1.2 – 1.8 V vs RHE), in contrast to unprotected RuO2 (RuO2@Ti) which showed an activity loss of nearly 90%. In addition, chronopotentiometry studies on Ru-MO@Ti (2.5 A cm-2 @ 1.7V) confirmed the high satiability of the Ru experienced only a minor increase in potential of 10 mV, while RuO2@Ti exhibited a significant degradation of 500 mV after 10 h. The superior stability of Ru-MO@Ti was possible due to impeded formation of higher valence ruthenium (Ru+8), a typical dissolution path for Ru-based electrocatalysts. Our work shows that multi-metal oxides have the potential to host and extend the lifetime of active metals and Ti substrates when used for water electrolysis in acidic media.

Figure 1