bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding the Effects of Transition Metal Impurities on Nickel (oxy) Hydroxide Electrocatalysts in Alkaline Media
Authors: Marquez-Montes Raul A. , Kawashima Kenta , Son Yoon Jun , Kalokowski Emma , Espinosa Michael , Smith Lettie A. , Chukwuneke Chikaodili E. , Miller Nathan , Mullins Charles Buddie
Published: February 2024

Nickel-based materials are widely used as critical components of electrochemical energy devices, including alkaline electrolyzers, capacitors, and alkaline batteries. These materials are often preferred because of their availability and low cost compared to precious metals, which makes them excellent candidates for accomplishing the decarbonization goals and electrifying our society. However, several studies have demonstrated that the incorporation of trace impurities from commercial alkaline electrolytes induces significant changes in the intrinsic activity, pseudocapacitance, and stability of Ni-based materials, resulting in erroneous descriptions of their performance. Thus, having a better understanding of the effects of these impurities will lead to practical ways to prevent or control their impact on electrochemical energy devices.

In this work, we study the incorporation of transition metals (i.e., Fe, Co, Cu) that form insoluble hydroxides in alkaline media over nickel (oxy) hydroxide electrocatalysts. We systematically examine how these trace impurities modify the OER activity, stability, and the pseudocapacitive properties of NiOOH. As depicted in Figure 1, KOH electrolytes containing trace impurities of Fe and Co induce significant changes in the OER onset potential of Ni(OH)2/NiOOH electrocatalysts, according to the irreversible charge increase measured through coulovoltammetry (QV) curves. Moreover, distinct redox peaks can be seen for each scenario. After aging in purified KOH electrolyte (Fig. 1a), the cyclic voltammogram (CV) of Ni(OH)2/NiOOH exhibits four oxidation peaks that can be ascribed to a mixture of both α and β structural phases (Fig. 1b) while aging in Fe-unpurified KOH promotes the α phase and shifts the redox peak anodically (Fig. 1c). Aging in Co-unpurified KOH promotes a more ordered β structural phase without changing the OER activity significantly (Fig. 1d), which is desirable for pseudocapacitive materials. Additional experiments examining the OER activity, stability, and capacitance provide valuable insights into these impurities, and specific strategies to prevent and minimize their effects will be discussed. Overall, this work illustrates the importance of tracking trace metal impurities in alkaline electrolytes to minimize undesirable effects in electrochemical energy devices.

Figure 1
A High-Entropy Oxide as High-Activity Electrocatalyst for Water Oxidation
Authors: Ni Shu , Kante Mohana V , Weber Moritz L , van den Bosch Iris C. G , Minne Emma , Heymann Lisa , Falling Lorenz J. , Gauquelin Nicolas , Tsvetanova Martina , Cunha Daniel M. , Koster Gertjan , Gunkel Felix , Nemšák Slavomír , Hahn Horst , Estrada Leonardo Velasco , Baeumer Christoph
Published: February 2024

High-entropy materials are an emerging pathway in the development of high-activity (electro)catalysts because of the inherent tunability and coexistence of multiple potential active sites, which may lead to earth-abundant catalyst materials for energy-efficient electrochemical energy storage. In this report, we identify how the multication composition in high-entropy perovskite oxides (HEO) contributes to high catalytic activity for the oxygen evolution reaction (OER), i.e., the key kinetically limiting half-reaction in several electrochemical energy conversion technologies, including green hydrogen generation. We compare the activity of the (001) facet of LaCr0.2Mn0.2Fe0.2Co0.2Ni0.2O3-δ with the parent compounds (single B-site in the ABO3 perovskite). While the single B-site perovskites roughly follow the expected volcano-type activity trends, the HEO clearly outperforms all of its parent compounds with 17 to 680 times higher currents at a fixed overpotential. As all samples were grown as an epitaxial layer, our results indicate an intrinsic composition–function relationship, avoiding the effects of complex geometries or unknown surface composition. In-depth X-ray photoemission studies reveal a synergistic effect of simultaneous oxidation and reduction of different transition metal cations during the adsorption of reaction intermediates. The surprisingly high OER activity demonstrates that HEOs are a highly attractive, earth-abundant material class for high-activity OER electrocatalysts, possibly allowing the activity to be fine-tuned beyond the scaling limits of mono- or bimetallic oxides.
Surface Dual-Modification of Nano-Cu2o for Controlling CO2 Electrochemical Reduction to Ethylene and Syngas
Authors: Luo Haiqiang , Li Bo , Ma Jian-Gong , Cheng Peng
Published: February 2024

Carbon dioxide (CO2) is an important substance in the natural carbon cycle, and the gradual increase of CO2 emissions has exceeded the amount that can be absorbed by the nature, which has brought a huge impact on climate conditions and ecological environment. In addition, CO2 is an important C1 resource, and it is of great significance to convert it by electrochemical methods to important chemical raw materials (such as ethylene and syngas) needed for human life. Cu2O is an ideal electrocatalyst due to its relatively low cost and unique product selectivity, as well as the abundant Cu reserves on the earth. However, there is still a lack of systematic studies on the improvement of the C2H4 selectivity of Cu2O-based catalyst and the regulation of product selectivity.

In this work, different exposed facet nano-Cu2O were obtained by induction of reducing agent. Combined with in-situ characterization and theoretical calculation, it was found that the terrace × step structure (332) crystal surface can significantly reduce the free energy of C-C coupling process, and greatly improve the selectivity of electrochemical CO2 reduction to C2H4, which is the highest value (74.1%) obtained by Cu2O based catalyst with neutral electrolyte.

Subsequently, the ZIF-8 shell is introduced in-situ on the surface of Cu2O nanoparticles. The coated ZIF-8 shell effectively regulates the hydrophilic and hydrophobic environment of the material, and provides a material exchange channel for reactants and product molecules simultaneously, which promote the desorption of CO molecules and improve the adsorption of CO2, realizing the switch of product from C2H4 to syngas.

In carbon dioxide reduction, it is an important strategy to modify the surface of metal/metal oxide by interface engineering to regulate the microenvironment at the reaction interface. In this paper, from the aspects of material design, synthesis and regulation of reaction products, the great advantages of facet structure and MOFs for improving the stability and activity of catalyst are demonstrated. Combined with in situ characterization and theoretical calculation, a new idea is provided for the design of efficient carbon dioxide electroreduction catalyst in the future.

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

Hydrogen is the way for connecting the renewable energy plants and consumers. However, achieving cheap, widespread hydrogen production and storage is complicated task. For hydrogen production the alkaline and acidic membrane electrolysers are used most widely. The membrane electrolysers have their limits, for example high standard potential of water splitting reaction, moderate efficiency, high cost and low durability. Decoupling oxygen evaluation reaction (OER) and hydrogen evaluation reaction (HER) is promising strategy to avoid using of membrane. Water electrolysis in separate cells was reported in 2017 by A. Landman et al., reaching the efficiency of 58% [1].

In 2022, we reported for the first time the amphoteric decoupled electrolysis by combining acid and alkaline cells [2]. The efficiency was enhanced due to reduced standard potential for water splitting by realizing HER in acidic environment but OER in alkaline. For maintaining decoupled amphoteric electrolysis, we connected acid and alkaline cell with the primary Pt electrodes and pseudocapacitive auxiliary electrodes (AE). For acid cell the AE electrode based on WO3 was used while for the alkaline cell electrodes based on Ni(OH)2. In proposed electrolyser two separate working cycles can be distinguished – different chemical processes occur at different polarities applied between primary Pt electrodes. The potential for gas generation depends on the polarity of the applied potential due to different chemical processes. In both polarities, hydrogen and oxygen are generated in separate cells. At the first cycle, ions are diffusing into the AEs and gases are generated with the Faradaic efficiency of 98 % and energetical efficiency of 43 %. At the second cycle, ions are released from AEs and gasses are generated with the Faradaic efficiency of 98 % and energetical efficiency of 201 %, providing the total energetical efficiency for whole operation of 71 %.

Herein we will discuss the effect of acid OER catalyst or the structure and composition of AEs on the performance of decoupled electrolysis, illuminating the pathways for bringing this concept as the main strategy for water splitting.

References

[1] A. Landman, H. Dotan, G.E. Shter, M. Wullenkord, A. Houaijia, A. Maljusch, G.S. Grader, A. Rothschild, Photoelectrochemical water splitting in separate oxygen and hydrogen cells, Nature Materials 16 (2017) 646-651.

[2] M. Vanags, G. Kulikovskis, J. Kostjukovs, L. Jekabsons, A. Sarakovskis, K. Smits, L. Bikse, A. Šutka, Membrane-less amphoteric decoupled water electrolysis using WO3 and Ni(OH)2 auxiliary electrodes, Energy Environ. Sci., 15 (2022) 2021-2028.
Effect of Chlorine on Copper Electrodissolution
Authors: Ayadathil Prajwal , Chatterjee Abhijit
Published: February 2024

A computational study on the role of adsorbed Cl ions on copper dissolution is presented. Extensive grand canonical Monte Carlo (GCMC) calculations using reactive force-field (ReaxFF) are used to check the formation chlorine (Cl) adlayer structures on Cu (100) surface as a function of the chemical potential (µ). From experimental studies conducted by other researchers it has been observed that Cl adlattice on Cu in c(2X2) at maximum coverage. We observe that at low µ, Cl adlayer is disordered and moves to ordered c(2X2) structure at high µ. The binding energy of Cl, oxygen (O), hydroxide (OH-) and H2O on Cu at different sites is calculated and compared with Density-functional theory (DFT) values. Metal surface is often highly uneven and rough during electrodissolution process. Therefore, we also discuss the adsorption isotherm, disorder-order transformation, and preferential adsorption sites for rough surfaces. Specific anion adsorption (SAA) of Cl involves partial charge transfer to Cu substrate and these effect the type of bond and bond strength which is also briefly discussed. The electrodissolution of Cu in the presence of Cl is modelled using kinetic Monte Carlo simulation to obtain the polarization curve.

Keywords: Adsorbed chlorine, electrodissolution, grand canonical monte carlo, molecular dynamics, ReaxFF, kinetic monte carlo.
Surface Curvature Effect on Dual-Atom Site Electrocatalysis
Authors: Ivanistsev Vladislav , Cepitis Ritums , Kongi Nadezda , Rossmeisl Jan
Published: February 2024

Oxygen, nitrogen, and carbon electrocatalysis are central in power-to-x innovations. Overpotentials of underlying processes are defined by the scaling relations between the adsorption energies of intermediates and, in turn, determine their efficiency. Our research explores the possibility of switching and tuning the scaling relations by applying metal-nitrogen-carbon (M-N-C) catalysts.

In this presentation, we introduce dual-atom site models and demonstrate the effect of surface curvature on oxygen and nitrogen electrocatalysis. Our Density Functional Theory (DFT) calculations show how curving the surface switches the scaling and significantly lowers overpotentials. For instance, we predict a bifunctional overpotential as low as 0.45 V, markedly lower than the theoretical limit of 0.74 V given by the OOH–OH scaling. [1]

Our study is among the first to investigate the surface curvature effect beyond the common scaling limitations. It will inspire the community to explore further this effect on oxygen electrocatalysis at M-N-C catalysts, as well as other challenging reactions and similarly curved materials.

Funding

V.I. and J.R. acknowledge the Danish National Research Foundation Centers of Excellence, The Center for High Entropy Alloys Catalysis (Project DNRF149), and the Independent Research Fund Denmark, grant no. 0217-00014B. V.I. receives funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska–Curie grant agreement no. 101031656. This research was also supported by the Estonian Research Council grant PSG250 and the EU through the European Regional Development Fund (TK141).

References

[1] R. Cepitis, N. Kongi, J. Rossmeisl, V. Ivaništšev, Surface Curvature Effect on Dual-Atom Site Oxygen Electrocatalysis, ACS Energy Lett. 8 (2023) 1330–1335.

Figure caption

Illustration of how reaching the optimum curvature lowers the ORR overpotential below the OOH–OH scaling-determined theoretical limit.

Figure 1
Highly Transparent and Stable N-Type Protective Layers for Spray Pyrolyzed CuO Thin Films for Photoelectrochemical Energy Conversion- a Comparative Study
Authors: Zala Devanshi , Shah Vardhan , Zala Devanshi
Published: February 2024

Various inexpensive and highly transparent n-type semiconducting oxides (ZnO, NiO, BaSnO3, Fe2O3, and Al2O3) are tested for their possible application as a protective layer on CuO photocathode. All the above films are synthesized by a highly scalable chemical spray pyrolysis technique. Optimized thin layers show high charge carrier concentration 1011- 1017 /cm3 and excellent electron mobility, improved charge separation capability. All of them show large and stable photocurrent density of CuO thin film photocathode when used as a protective layer. Time-Resolved Photoluminescence (TRPL) is measured to understand the carrier lifetime in them. The photo-electrochemical behavior of all electrodes is performed in the dark and illumination with neutral (pH ~8) and alkaline (pH ~14) electrolytes. Photostability of all prepared heterojunctions ZnO/CuO, NiO/CuO, BaSnO3/CuO, Fe2O3/CuO, and Al2O3/CuO photocathodes are measured under continuous AM 1.5 G illumination for 300 s. Comparative study of solar to chemical conversion efficiency of fabricated photocathodes are presented.
Promoting Pd-Catalyzed Conversion of CO to Formate
Authors: Wang Lei
Published: February 2024

Electrochemical CO2 reduction offers exciting opportunities in turning the waste carbon into value-added chemicals/fuels. Among different CO2 reduction products, formate has attracted particular interest, as it shows promising near-term economic feasibility. Pd-based electrocatalysts have demonstrated excellent selectivity towards formate production, however, only within a narrow potential window of 0 V to -0.25 V vs. RHE. It has shown that Pd-based electrocatalysts suffer from the potential-dependent deactivation pathways (α-PdH to -PdH phase transition, CO poisoning, etc.) and quickly loss their activity towards formate production. Thus, it is desirable to establish new strategies to enable Pd-based CO2 reduction over a broader potential window to achieve both energy efficient and practical relevant formate production.

In this work, we discovered that ligands, i.e., polyvinylpyrrolidone, decorated Pd surface exhibits an unexpected promotion effect on CO2 electroreduction. Specifically, these decorated Pd can afford selective formate production at a much-extended potential window (beyond -0.7 V vs. RHE) with significantly improved activity (14-times enhancement at -0.4 V vs. RHE) compared to that of the pristine Pd surface. Combined results from physical/electrochemical characterizations, kinetic analysis and first principal simulations suggest that the capping ligand can effectively stabilize the Pd species with high valence state (Pdẟ+) resulted from the catalyst synthesis and pretreatments. These Pdẟ+ species are responsible for the inhibited phase transition of α-PdH to β-PdH, as well as the suppression of CO and H2 formation. Overall, our study confers a desired catalyst design principle: introducing positive charges into Pd-catalysts to enable efficient and stable CO2 to formate conversion.
Use of Surface Features with Controlled Kinetics to Verify Fits of Scanning Electrochemical Microscopy Images
Authors: Leslie Nathaniel , Mauzeroll Janine
Published: February 2024

Scanning Electrochemical Microscopy (SECM) is a promising technique for measuring kinetics of redox reactions at surfaces. The conversion of the current map - produced by rastering an electrode over the surface - to a maps of the rate constant of reactions at the surface requires computer modelling and statistical techniques. Experimentally obtained SECM images are necessary to validate computer models that will be used to test these fitting procedures.

The largest challenge was finding or creating samples that have reactive sites of known kinetics that were sufficiently slow to be activation-limited. This was achieved by producing small precious metal electrodes embedded in an insulating surface. The exchange currents of these electrodes were characterized using cyclic voltammetry at high scan rates[1,2] so that the rate constant of the electrodes could be effectively controlled by the potential at which they were poised. SECM images of these electrodes can compared to computer simulations to verify that they produced correct results.

[1] Nicholson, R.S. Theory and Application of Cyclic Voltammetry for Measurement of Electrode Reaction Kinetics. Anal. Chem. 1965, 37, 11, 1351–1355

[2] Mirkin, M.V.; Bard, A.J. Simple Analysis of Quasi-Reversible Steady-State Voltammograms. Anal. Chem. 1992, 64, 19, 2293–2302
Quantifying Volume Change in Porous Electrodes Via the Multi-Species, Multi-Reaction Model
Authors: Garrick Taylor R. , Fernandez Miguel , Verbrugge Mark , Labaza Christine , Mollah Rafid , Koch Brian , Jones Matthew , Gao Jing , Gao Xiujie , Irish Nicholas
Published: February 2024

Automotive manufacturers are working to improve individual cell and overall pack design by increasing their performance, durability, and range, while reducing cost; and active material volume change is one of the more complex aspects that needs to be considered during this process. As the time from initial design to manufacture of electric vehicles is decreased, design work that used to rely solely on testing needs to be supplemented or replaced by virtual methods. As electrochemical engineers drive battery and system design using model-based methods, the need for coupled electrochemical/mechanical models that take into account the active material change utilizing physics based or semi-empirical approaches is necessary[1-8]. In this study, we illustrated the applicability of a mechano-electrochemical coupled modeling method considering the multi-species, multi-reaction model as popularized by Verbrugge[9-14] and Baker. To do this, validation tests were conducted using a computer-controlled press apparatus that can control the press displacement and press force with precision. The coupled MSMR volume change model was developed and its applicability to graphite and NMC cells was illustrated. The increased accuracy of the model considering the coupled MSMR volume change approach shows in the importance of accounting for individual gallery volume change behavior on cell level predictions.

References

T. R. Garrick, K. Kanneganti, X. Huang and J. W. Weidner, J Electrochem Soc, 161, E3297 (2014).

T. R. Garrick, Y. Dai, K. Higa, V. Srinivasan and J. W. Weidner, Ecs Transactions, 72, 11 (2016).

T. R. Garrick, K. Higa, S.-L. Wu, Y. Dai, X. Huang, V. Srinivasan and J. W. Weidner, J Electrochem Soc, 164, E3592 (2017).

T. R. Garrick, X. Huang, V. Srinivasan and J. W. Weidner, J Electrochem Soc, 164, E3552 (2017).

D. J. Pereira, J. W. Weidner and T. R. Garrick, J Electrochem Soc, 166, A1251 (2019).

D. J. Pereira, M. A. Fernandez, K. C. Streng, X. X. Hou, X. Gao, J. W. Weidner and T. R. Garrick, J Electrochem Soc, 167, 080515 (2020).

T. R. Garrick, J. Gao, X. Yang and B. Koch, J. Electrochem. Soc. (2021).

D. J. Pereira, A. M. Aleman, J. W. Weidner and T. R. Garrick, J Electrochem Soc, 169, 020577 (2022).

M. Verbrugge, D. Baker and X. Xiao, J Electrochem Soc, 163, A262 (2016).

M. Verbrugge, D. Baker, B. Koch, X. Xiao and W. Gu, J Electrochem Soc, 164, E3243 (2017).

D. R. Baker and M. W. Verbrugge, J Electrochem Soc, 165, A3952 (2018).

D. R. Baker and M. W. Verbrugge, J Electrochem Soc, 167, 013504 (2019).

D. R. Baker, M. W. Verbrugge and W. Gu, J Electrochem Soc, 166, A521 (2019).

M. W. Verbrugge, X. Xiao and D. R. Baker, J Electrochem Soc, 167, 080523 (2020).
Monitoring Copper Ion Leaching from a Metalloporphyrin-Based Cathode for Rechargeable Magnesium Batteries
Authors: Philipp Tom , Abouzari-Lotf Ebrahim , Fichtner Maximilian , Mauzeroll Janine , Schougaard Steen Brian , Kranz Christine
Published: February 2024

Great efforts are being undertaken to characterize the fundamental processes of solid electrolyte interphase (SEI) formation, degradation, and initial conditioning steps of battery electrode materials, including organic electrode materials.[1] Imaging techniques, such as focused ion beam / scanning electron microscopy (FIB/SEM) tomography in combination with element mapping using energy- and wavelength-dispersive X-ray spectroscopy are employed to gain insight into distribution, interconnectivity, and porosity of active materials as well as electrolyte penetration and their influence on degradation processes after longer cycling times.[2] Additionally, electrochemical impedance spectroscopy[3] and anodic stripping voltammetry[4] are used to shed light on those processes. The metalloporphyrin-based material [5,15-bis(ethynyl)-10,20-diphenylporphinato]copper(II) (CuDEPP) has been used as an interesting material for cathodes and anodes of various battery chemistries. These materials undergo initial self-conditioning by electro-polymerization for monovalent ions. With respect to multivalent ions, like magnesium, this polymerization is far less pronounced and an exchange of the copper from the CuDEPP by magnesium ions appears to be occurring.[5] Gaining insight into this trans- or demetallation process induced by parameters like the electrochemical driving force during galvanostatic cycling is a complex analytical challenge.

We report the use of Hg ultramicroelectrodes and anodic stripping voltammetry as a sensitive strategy to detect copper ion leaching from metalloporphyrin-based CuDEPP composite electrodes. We demonstrate in-situ/intermittent monitoring of copper ion release during the initial self-conditioning step of the active material while galvanostatic cycling of the battery electrode in dimethoxy ethane. This method could be used to assess the release of an ionic species from complex systems, like composite battery electrodes.

References:

[1] Peled and Menkin, J. Electrochem. Soc.
2017, 164, A1703.

[2] Philipp, Neusser, Abouzari-Lotf, Shakouri, Wilke, Fichtner, Ruben, Mundszinger, Biskupek, Kaiser, Scheitenberger, Lindén and Kranz, J. Power Sources, 2022, 522, 231002.

[3] Iurilli, Brivio and Wood, J. Power Sources, 2021, 505, 299860.

[4] Hatami, Polcari, Hossain, Ghavidel, Mauzeroll and Schougaard, J. Electrochem. Soc.
2022, 169, 040526.

[5] Abouzari-Lotf, Azmi, Li, Shakouri, Chen, Zhao-Karger, Klyatskaya, Maibach, Ruben and Fichtner, ChemSusChem.
2021, 14, 1840.

This work contributes to the research performed at CELEST (Center for Electrochemical Energy Storage Ulm - Karlsruhe) and was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy – EXC 2154 – Project number 390874152 (POLiS Cluster of Excellence).
Achieving Tunable Selectivity and Activity of CO2 Electroreduction to CO Via Bimetallic Silver-Copper Electronic Engineering
Authors: Li Meng , Hu Yue , Dong Gang , Wu Tianci , Geng Dongsheng
Published: February 2024

Electrocatalytic CO2 reduction reaction (E-CO2RR) provides a sustainable way to convert greenhouse gases into value-added chemicals and small-molecule fuels[1, 2]. However, the efficient production of a single product remains a challenge. To this end, we have constructed the Ag-Cu bimetallic system as an experimental platform to investigate the process of electronic effects on the selectivity and activity of CO products in more detail. Specifically, metallic Ag is used as the matrix and different levels of Cu (Ag, Ag99Cu1, Ag96Cu4, Ag70Cu30, Ag30Cu70, Cu) are added as modifiers of the 3d orbital electron density of the system to adjust the adsorption strength of *H (key intermediates for H2 formation), *COOH and *CO (the key intermediate of CO formation) intermediates. Combining the electrochemical test results with the DFT calculations, we obtain the following trends:

The addition of trace amounts of Cu (Ag99Cu1, Ag96Cu4) can greatly enhance the catalytic potential of Ag for the selective production of CO products at low potentials, achieving near 100% selectivity for CO products (Ag96Cu4, -1V vs. RHE).

The observed rate determining step of the reaction on Ag30Cu70 from CO2–*COOH to *COOH–*CO implies that adding too much Cu or leading to strong adsorption of *CO results in poisoning.

It was observed that Ag96Cu4 had the optimum CO selectivity and Ag70Cu30 had the optimum CO activity current, which is different from previous concentrations on the same catalyst. (Figure 1a, b)

We attribute the above findings to Ag96Cu4 effectively reducing the free energy of the formation of *COOH while maintaining a relatively high theoretical overpotential for hydrogen evolution reaction (HER), thus achieving the best CO selectivity (Figure 1c, d). While the Ag70Cu30 together activates the CO2RR and HER processes and shows relatively low formation energies of *COOH and *H, the compromised thermodynamic barrier and product selectivity allows for the best CO partial current density to be exhibited (Figure 1c, d). We believe that the electron effect will serve as an effective platform for screening selective and active catalysts.

Figure1. a) FECO and b) jCO as a function of the proportion of Cu in AgxCu100-x series catalysts. c, d) The calculated free energy diagrams of CO2RR to CO and HER on fcc Ag (111), Ag96Cu4 (111), Ag70Cu30 (111), Ag30Cu70 (111) and Cu (111) surfaces at 0 V vs. RHE, respectively.

Reference

Grätzel, M., Nature
2001,
414 (6861), 338-344. DOI 10.1038/35104607.

Zheng, Y.; Vasileff, A.; Zhou, X.; Jiao, Y.; Jaroniec, M.; Qiao, S.-Z., Journal of the American Chemical Society
2019,
141 (19), 7646-7659. DOI 10.1021/jacs.9b02124.

Figure 1
Electrochemical Valorization of Glycerol: Catalyst Development and Product Analysis
Authors: Angizi Shayan , Yelekli Kirici Ecem , Higgins Drew Higgins
Published: February 2024

The growing interest in biofuels as a substitute for traditional fossil fuels has raised environmental concerns about the extensive production of their by-products. Among these by-product, Glycerol, which accounts for over 10% of the total by-products, resulted in the production of nearly 4 billion liters in 2020. (1) Glycerol is a polyol organic molecule, viscous, and water-soluble liquid that if not disposed of properly, it can have detrimental impacts on the environment, including soil and water pollution, ultimately contributing to an increase in the carbon footprint. Hence, addressing this growing concern has prompted a surge of interest in developing sustainable and economically viable techniques for converting glycerol into value-added products.

The electrochemical glycerol oxidation reaction (GOR) is a cost-effective and reliable method to enable circular economy practices by selectively producing highly value-added products such as dihydroxyacetone, glyceric acid, and glycolic acid from glycerol. However, it requires the development of active, selective, and stable electrocatalysts to steer GOR at low overpotentials. To date, catalysts based on platinum group metals (PGMs) have outperformed other GOR catalysts in terms of activity. However, in addition to the high cost of fabrication, these catalysts are susceptible to surface poisoning by glycerol intermediates, thereby impeding their commercialization due to the absence of long-term stability. (2) As a result, developing electrocatalysts based on earth-abundant element has become the focal point in GOR catalyst research.

Here in, we highlight the latest advancements in the development of low-PGM content GOR catalysts. Our discussion focuses on the strategies for understanding how the type and concentration of PGM can influence selectivity, with a particular emphasis on the significance of GOR overpotentials. We also aim to highlight the inconsistencies in GOR product analyses, specifically regarding the use of H-NMR analysis, with an ultimate goal of advancing accurate GOR product quantification.

References

Nomanbhay S, Hussein R, Ong MY. Sustainability of biodiesel production in Malaysia by production of bio-oil from crude glycerol using microwave pyrolysis: a review. Green Chemistry Letters and Reviews. 2018;11(2):135-57.

Li T, Harrington DA. An Overview of Glycerol Electrooxidation Mechanisms on Pt, Pd and Au. ChemSusChem. 2021;14(6):1472-95.
Measurement of Surface Diffusion at Electrochemical Interfaces Using in Situ Linear Optical Diffraction
Authors: Kattwinkel Lasse , Magnussen Olaf M.
Published: February 2024

Surface diffusion processes play an important role in many reactions at electrode surfaces and are of relevance to electrocatalysis, electrodeposition, and many other areas. Such processes have therefore been extensively studied on solids under vacuum conditions with a variety of different methods. In sharp contrast, only few studies exist to measure surface diffusion in electrochemical environment due to the lack of suitable methodology. We aim on partially filling this gap by introducing the all-optical in situ LOD methodology, which allows to measure surface diffusion rates over a wide range and thus overcomes limitations of established methods that are mostly restricted to slow diffusion rates. The method is based on the generation of a periodic spatial modulation of adsorbates using two interfering laser pulses. The subsequent equilibration of this pattern and thus the diffusion rate of adsorbates is probed by the linear optical diffraction (LOD) signal from a second laser.

First proof-of-principle measurements were performed on sulfur diffusion on the Pt(111) electrode. For this purpose, the optical and electrochemical properties of this systems were investigated first, including studies of the optical reflectance change induced by chemisorbed sulfur (Sad) and investigations of the Sad oxidation mechanism. The subsequent studies of Sad surface diffusion revealed potential and coverage dependent diffusion rates which were at least an order of magnitude faster than under vacuum conditions. Supported by numerical simulations, the implications of strong adsorbate-adsorbate interaction combined with different grating modulation depths to the temporal evolution of the LOD signal were demonstrated and data accuracy and pitfalls of the method were discussed.

Kattwinkel and Magnussen, ACS Meas. Sci. Au, in press (2023), https://doi.org/10.1021/acsmeasuresciau.2c00066

Kattwinkel and Magnussen, Electrochimica Acta 434, 141297 (2022), https://doi.org/10.1016/j.electacta.2022.141297
X-Ray Photoelectron Spectroscopy Investigation of Catalyst-Ionomer Interactions for PEMFC Electrodes
Authors: Foster Jayson , Baez-Cotto Carlos , Schneider Patrick , Ahmadi Maryam , Jankovic Jasna , Zamel Nada , Mauger Scott A , Pylypenko Svitlana
Published: February 2024

Proton exchange membrane fuel cells (PEMFCs) are an increasingly attractive clean energy technology to meet stationary and transportation energy demands without contributing to greenhouse gases. Further developments to PEMFCs are primarily focused on improving the cathode catalyst layer which uses expensive platinum catalysts to compensate for the sluggish oxygen reduction reaction and a thin film of proton conductive ionomer to aid in mass transport. It is understood that the Pt-based carbon supported catalyst may experience heterogeneity in ionomer coverage motivating further studies of catalyst layers with focus on catalyst-ionomer interface. Specifically, it is important to improve understanding of how support morphology, Pt catalyst loading, amount of ionomer, and method of catalyst layer coating affect the catalyst-ionomer interface to identify potential pathways to further to improve catalyst utilization as the technology increases in scalability.

This study focuses on investigating the catalyst-ionomer interface using x-ray photoelectron spectroscopy (XPS) as it is highly surface sensitive (top ~3-10 nm) and can capture subtle differences in the chemistry of the catalyst, ionomer, and support at the catalyst-ionomer interface. Due to the ionomer’s inherent susceptibility to x-ray induced damage, XPS analysis was conducted with a recently developed protocol to mitigate instrumental artefacts. In this work, elemental ratio quantification metrics derived from XPS are used to track surface ionomer content relative to amount of Pt nanoparticles and the amount of carbon support producing two parameters. These parameters are used to show how variations in carbon support graphitization, Pt loading, ionomer chemistry, and ionomer loading affect the catalyst-ionomer interface in unique ways. Additionally, changes to the catalyst-ionomer interface after degradation were also assessed, comparing beginning of life and end of life samples. Further, this presentation will also discuss the evolution of the catalyst-ionomer interface under humidified conditions which was assessed with in situ XPS. This talk highlights the potential of XPS to improve our understanding of relationships between surface properties, processing, performance, and durability and motivates future work in understanding catalyst layer fabrication, performance, and degradation.
The Impact of Operando Analysis in the Understanding of Oxygen Evolution Reaction Ranging from Intrinsic to Technical Scales
Authors: Spanos Ioannis , Tesch Marc Frederic , Lim Ahyoun , Schlögl Robert
Published: February 2024

The development of state of the art and cost-effective catalyst materials for the sluggish oxygen evolution reaction (OER) is of paramount importance for realizing practical water electrolysis for green hydrogen production. Crucial for this endeavor is the determination of the OER mechanism and a better understanding of all these background processes that affect catalyst activity and stability. Thus, to further elucidate all these processes operando characterization techniques performed dynamically during OER are used as powerful tools which allow monitoring of key reaction intermediates, active sites, charge transfer and material transformation coupled processes etc. In this work we summarize our recent investigations covering noble and 3d transition metal-based OER electrocatalysts by different operando techniques and we show the importance of such techniques in the unraveling catalyst activation/deactivation mechanisms. Thus, our efforts are ranging from half-cell characterization of electrocatalyst intrinsic properties to single-cell analysis of phenomena occurring during their technical operation.

Operando techniques like eQCM, XAS, ICP-OES and single cell testing will be presented aiming to emphasize on the critical role of operando in the understanding of fundamental aspects of electrochemistry [1], like intrinsic catalyst properties (Fig. 1a), the effect of electrolyte impurities such as Fe (Fig. 1b-d) on Ni-based electrocatalysts in alkaline environment [2] as well as mechanistic phenomena taking place during catalyst activation (Fig. 1e-f) leading to the formation of the active sites for OER in acidic environment [3].

References

[1] Tesch MF, Bonke SA, Jones TE, Shaker MN, Xiao J, Skorupska K, Mom R, Melder J, Kurz P, Knop‐Gericke A, Schlögl R, Hocking RK, Simonov AN: Angew Chem Int Ed 2019, 58:3426-3432.

[2] Spanos I, Tesch MF, Yu M, Tüysüz H, Zhang J, Feng X, Müllen K, Schlögl R, Mechler AK: ACS Catal 2019, 9:8165-8170.

[3] Papakonstantinou G, Spanos I, Dam AP, Schlögl R, Sundmacher K: Phys Chem Chem Phys 2022, 24:14579-14591.

Figure 1
(Invited) Considerations in Sample Environment and Data Processing for Operando Cell Studies by Neutron Depth Profiling
Authors: Weaver Jamie Lynn
Published: February 2024

Neutron depth profiling (NDP) is a nominally non-destructive analytical technique used to measure select isotopes (6Li, 14N, 10B, etc...) in a diversity of materials. NDP can be conducted on operating Li-ion cells and be used to provide researchers real-time information about cell formation, conductance, and resilience. The increased use of NDP for electrochemical studies within the past decade has inspired the development of new sample preparation and data reduction strategies. Select topics that have been studied in the U.S. have included issues of neutron attenuation and scattering due to the addition of a protective capping layer over a cell, the possible need for matrix matched standards for complex materials, and the streamlining of the NDP data reduction procedure. Several challenges remain, however, including improving NDP data acquisition and reduction methods for detectable, low-Z isotopes such as 14N and 35Cl and improving upon the NDP data reduction and processing procedures so that they are more accessible to non-instrument specialists. All these topics will be discussed in this presentation.
Trifluoroacetamide-Based Eutectic Electrolyte with High Oxidative Stability
Authors: Yoshii Kazuki , Maeyoshi Yuta , Uto Takuya , Moriuchi Toshiyuki
Published: February 2024

Recently, the development of batteries with high energy densities is strongly expected due to the downsizing of electronic devices and the popularization of electric vehicles. The highly concentrated eutectic electrolyte has been recognized as a promising candidate of electrolyte for the next generation batteries. Various compounds such as ether, sulfolane, acetonitrile, and others have been studied as solvents for eutectic electrolytes. Some kinds of amide-based eutectic electrolytes have been also reported so far, whereas their oxidation stability is insufficient for application as electrolytes for the high-voltage cathode materials in lithium-ion batteries. In the present study, to improve the oxidation stability of amide-based eutectic electrolytes, we have prepared trifluoroacetamide-based eutectic electrolytes with lithium bis(fluorolsulfonyl)amide (LiFSA) and investigated their solution structure, physicochemical properties, and the potential for the electrolytes. Eutectic electrolyte composed of LiFSA and N-methyltrifluoroacetamide (MTFAA) at a molar ratio of 1:1.5 exhibited the reversible deposition and dissolution of lithium and very high electrochemical oxidation stability. We have also demonstrated the stable charge/discharge cycling of a high-voltage Li metal battery with a 5 V-class LiNi0.5Mn1.5O4 cathode using the electrolyte.
Ionic Liquid Initiated Corrosion Products on Steel
Authors: Dobryden Illia , Li Sichao , Zhao Wei , Yu Shun , Siljeström Sandra , Persson Dan , Sjövall Peter , Rutland Mark
Published: February 2024

Ionic liquids (ILs ) are achieving great interest as electrically addressable lubricants. The demands of lubrication of inaccessible systems, such as wind turbines, coupled with the lubrication paradigm shift engendered by electric vehicles makes IL lubricant additives extremely attractive. The interaction of ILs with steel surfaces and initiation of corrosion need to be urgently addressed, since ILs are in principle organic salts, and water is ubiquitous , even at ppm levels. In this study we have applied a set of surface sensitive advanced techniques, such as Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), Confocal Raman Microscopy, Nano-IR and FTIR microscopy as well as scattering GISAXS, to investigate the formed corrosion products in tribo films containing designer ionic liquids at steel surfaces. The trihexyl-(tetradecyl)phosphonium-bis(oxalato)borate [P6,6,6,14][BOB] ionic liquid and a specially deposited AISI 52100 steel were used in this study. The IL breakdown and various surface-formed corrosion products were imaged and analyzed. The formation of iron oxides and various borate and phosphate-containing products, and their interrelation, is observed and mechanistically discussed.
Comparative Study on Transport Property of Asymmetric Fluorosulfonyl(trifluoromethylsulfonyl)Amide-Based Phosphonium Ionic Liquids
Authors: Tsunashima Katsuhiko , Kikuchi Seiya , Nishikawa Kosuke , Tsuchida Yusuke , Kawaji Takatoshi , Funasako Yusuke , Yamada Hirohisa
Published: February 2024

Room-temperature ionic liquids (RTILs), i.e. organic molten salts with melting points below ambient temperature, have been regarded as potential electrolytes for various electrochemical systems, because RTILs have unique physicochemical properties such as favorable solubility of organic and inorganic compounds, relatively high ionic conductivity, no measurable vapor pressure, high thermal stability, low flammability, etc. The quaternary phosphonium cation based RTILs have attracted attention in recent years due to their high chemical and thermal stabilities. We have proposed and synthesized a class of low viscous and highly conductive RTILs based on triethylalkylphosphonium cations in combination with typical sulfonylamide-based anions, e.g. bis(trifluoromethylsulfonyl)amide (N(SO2CF3)2
-, TFSA) and bis(fluorosulfonyl)amide (N(SO2F)2
-, FSA) anions.1,2 Our recent approaches include a design and synthesis of low-melting phosphonium based RTILs together with asymmetric fluorosulfonyl(trifluoromethylsulfonyl)amide (N(SO2F)(SO2CF3)-, FTA) anion. In this work, we report the transport property and unique viscosity behavior of several FTA anion based phosphonium RTILs as shown Fig. 1.

The FTA-based phosphonium RTILs was synthesized by aqueous ion exchange reaction of the precursor quaternary phosphonium halides with lithium FTA. The crude RTILs obtained were hydrophobic and purified by washing with pure water several times in order to remove residual metal and halide ions. The RTILs thus prepared were dried under high vacuum for at least 1 day. The physicochemical properties of RTILs, e.g. density, viscosity, conductivity (ac impedance method), were measured at elevated temperatures under argon atmosphere.

Several low-melting phosphonium RTILs were successfully prepared by combination with FTA anion (P2225, P2228 and P4441-FTA). All FTA-based phosphonium RTILs showed typical temperature dependent behaviors for density, viscosity and electrical conductivity. The conductivities of FTA-based phosphonium RTILs were higher and lower than those of corresponding TFSA- and FSA-based phosphonium RTILs, respectively; however, it should be noted that the viscosities of FTA-based phosphonium RTILs were the lowest in the phosphonium RTILs as depicted in Fig. 2. To our knowledge, such a unique viscosity behavior has not been previously reported in the FTA-based ammonium based RTILs. The detailed transport property and electrolytic behaviors such as the Arrhenius plots of viscosity and conductivity with VTF fitting and the Walden plots will be also discussed in comparison with both corresponding TFSA- and FSA-based RTILs.

References

1) K. Tsunashima, et al, Electrochem. Commun., 9, 2353 (2007).

2) K. Tsunashima, et al, Electrochem. Commun., 13, 178 (2011).

Figure 1
(Invited) Structure Reconstruction Strategy for High-Energy Lithium Ion Batteries without Capacity Sacrifice
Authors: Liu Qi , Yang Tingting
Published: February 2024

Lithium nickel oxides (LiNiO2) is considered to be a promising high-energy-density cathode material in lithium-ion batteries (LIBs)1-3. However, its inherent Li off-stoichiometry composition and structural deterioration under various phase transition usually bring about low initial capacity and rapid capacity decay4,5. To stimulate the high capacity and extend the lifespan for LiNiO2 in LIBs, the structure reconstruction method is applied to modify the cathode materials by Mo regulating (Mo-LiNiO2). The cross section high-resolution transmission electron microscope and energy dispersive spectroscopy (TEM-EDS) images show that the concentration of Mo is gradually decreased from the surface to the bulk center. Correspondingly, the concentrated Ni2+ ions in the surface of Mo-LiNiO2 build up the rock-salt phase layer with 5-20 nm in the surface, which plays the pinner effect based on in situ X-ray diffraction (XRD) patterns to enable excellent mechanical and structural reversibility for the layered Mo-LiNiO2 upon cycling. Finally, electrochemical results show that the modified cathode materials (Mo-LiNiO2) has a high capacity (~235 mAh g–1 at 0.1C) and the stable cycle performance (~94% for 90 cycles at 1C) as shown in Figure 1. The Mo-LiNiO2 cathode can provide high capacity and cycle stability with low material cost, which is suitable for the long service life of electric vehicles, further realizing a commercially viable cathode materials for LIBs.