bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving the Performance for Direct Electrolysis of CO2 in Solid Oxide Electrolysis Cell with Sr1.9Fe1.5Mo0.5 O6
-
δ Electrode Via Infiltration of Pr6O11 Nanoparticles
Authors: Wang Wanhua , Li Haixia , Park Ka-Young , Lee Taehee , Chen Fanglin (Frank)
Published: November 2022

High temperature direct CO2 electrolysis based on solid oxide electrolysis cell (CO2-SOEC) is a promising technology to convert carbon dioxide to carbon monoxide with a high current density and Faradaic efficiency. The exploration for suitable cathodes with desirable catalytic activity is a grand challenge for the development of CO2-SOEC. Sr2Fe1.5Mo0.5O6
-
δ is often used as the cathode material for SOEC, but suffers from insufficient activity for CO2 reduction reaction (CO2RR). In this work, nanoscale Pr6O11 was infiltrated into the Sr1.9Fe1.5Mo0.5O6
-
δ (SFM) electrode to promote the CO2RR performance in SOEC. The optimal loading of Pr6O11 is systematically investigated. At 800°C, the current density of the Pr6O11 infiltrated SFM cathode with a Pr6O11 loading of 13.4wt.% reaches 1.58 A/cm2 at 1.5V, which is 2.5 times higher than that of SFM cathode (0.63 A/cm2) at the same operating conditions. X-ray photoelectron spectroscopy characterization and temperature-programmed desorption of CO2 measurements indicate that the adsorption and desorption ability of CO2 of SFM cathode are improved by the infiltration of Pr6O11. Further, the polarization resistance of SFM cathode has significantly decreased with the infiltrated Pr6O11. These results demonstrate that the infiltration of Pr6O11 is a promising approach for increasing CO2RR activity.

Acknowledgements

Financial support from the U.S. Department of Energy (DE-EE0009427) and NASA EPSCoR (Grant # 80NSSC20M0233) is greatly appreciated.
Localized Surface Oxygen Ion Transport in Sto and YSZ Observed Via Quasi in Situ Scanning Probe Microscopy
Authors: Kang Hung-Sen , Garcia ThomasJae , Li Haoyu , Liu Ziqi , Lee Min Hwan
Published: November 2022

Ionic transport in solid oxides lays the fundamentals of solid-state electrochemical energy and sensor devices. While ionic transport in polycrystalline oxides has been studied for decades, most studies are reliant upon macro-scale observations where direct revelation of localized transport behavior is not feasible. In this presentation, we report a direct quasi in situ observation of oxygen ion transport in SrTiO3 (STO) and Y2O3-stabilized ZrO2 (YSZ) by leveraging scanning probe microscopy variants.

First, a cluster of oxygen vacancies formed by an electrical bias at a tip-sample contact. Then, we exposed the sample to an elevated temperature to allow a facilitated ionic diffusion. The resultant lateral distribution of oxygen vacancies was obtained by Kelvin probe force microscopy (KPFM). Depth-wise distribution of oxygen vacancies were acquired by a combination of in situ etching with a diamond-coated probe and KPFM scans, which enabled an observation of ionic charge transport in a highly localized fashion in both lateral and depth-wise directions.

From 3D spatial charge imaging, the activation energies of surface ionic diffusion in the lateral direction (Esurf) and those of bulk diffusion in the depth-wise direction (Ebulk) were quantified; for YSZ, Esurf = 0.34 eV and Ebulk = 1.13 eV, and for STO, Esurf = 0.50 eV and Ebulk = 1.30 eV. It was also found that the surface ion diffusivity of YSZ (1.68 × 10-8 cm2/s) is more than 3 orders of magnitude higher than that of STO (4.86 × 10-12 cm2/s), and that bulk diffusivity of YSZ (1.70 × 10-11 cm2/s) is more than 7 orders of magnitude higher than that of STO (7.61 × 10-19 cm2/s). To the best of our knowledge, this is the first study where the ionic diffusivities along the surface and into the bulk are separately quantified by direct localized observations of 3D distribution of ionic species, as opposed to a bulk measurement from which diffusivities were indirectly deduced.

The authors acknowledge the support by National Science Foundation (DMR 1753383).
Development of SOEC Performance Model Based on Cell Performance
Authors: Mugikura Yoshihiro , Imabayashi Takumi , Asano Koichi
Published: November 2022

Central Research Institute of electric Power Industry (CRCIEPI) has developed original SOFC performance evaluation method and applied to a wide variety of cells. Based on the SOFC performance evaluation method, a new SOEC performance evaluation method has been developed this time. By this evaluation method, the difference between the open circuit voltage and the cell voltage can be expressed by the internal resistance loss (measured value), the fuel electrode overvoltage, the oxygen electrode overvoltage, and the Nernst loss.

In this study, cell performance before and after the CO2 direct electrolysis test was compared by SOFC and SOEC evaluation methods and clarification of cell degradation factor by CO2 direct electrolysis.
Interface Problems in Solid Oxide Electrolysis Cells
Authors: Zhang Qian , Cox Dalton , Regalado Vera Clarita Yosune , Ding Hanping , Tang Wei , Du Sicen , Chadwick Alexander F. , Thornton Katsuyo , Ding Dong , Barnett Scott A , Voorhees Peter W.
Published: November 2022

In this talk, I introduce topics, that I have been working on, in solid oxide electrolysis cells involving complicated interfacial structures and dynamics of interfaces. Then I will focus on my recent work on nickel (Ni) particle migration in electrodes consisting of Ni, yttria-stabilized zirconia (YSZ), and pores during the operation of oxygen-ion conducting solid oxide electrolysis cells (o-SOECs) and Faraday efficiency in proton-conducting solid oxide electrolysis cells (p-SOECs) under electrolysis operations. SOECs can have a significant impact on climate change over the next decade and beyond, in applications such as balancing renewable grid electricity via electrolytic fuel production. However, long-term performance degradation remains a key issue that may limit further implementation of O-SOECs, and the dependency of operation conditions on Faraday efficiency in P-SOECs has been under debate. In particular, in Ni/YSZ/pore electrode of O-SOEC, a phase-field model is proposed that employs the Ni-YSZ 3D microstructure as the initial condition and large-scale numerical simulation is implemented that predicts the directional Ni migration. The results are thus directly comparable to experimental observations. Quantitative predictions of the evolution of the Ni/YSZ/pore system's microstructures due to Ni particles' migration are studied through theoretical analysis and data analysis. In P-SOECs, an electrochemical model is proposed to study the dependency of Faraday efficiency on operation conditions for P-SOECs with yttrium-doped barium zirconates (BZY) and co-doping barium zirconate-cerate oxides with ytterbium and yttrium (BCZYYb) as electrolytes respectively. Our numerical predictions are verified by experimental results obtained in INL. An optimal structure of electrolyte is proposed to boost the Faraday efficiency in P-SOECs.
(Invited) High Efficiency, Ultras-table Solar Hydrogen Production Utilizing Industry Standard Materials
Authors: Mi Zetian
Published: November 2022

Solar water splitting and green hydrogen fuel production has been extensively studied but is confronted with fundamental challenges of simultaneously achieving both high efficiency and long-term stability. The commonly utilized approaches include photovoltaic-electrolysis (PV-E), photoelectrochemical, and photocatalytic processes, and numerous materials have been studied. In this presentation, I will report on our recent developments of gallium nitride (GaN) based photoelectrochemical and photocatalytic water splitting studies. GaN is one of the most produced semiconductors. By alloying with indium, the energy bandgap of InGaN can be continuously varied across nearly the entire solar spectrum. Recent studies have further shown that the conduction and valence band edge positions of InGaN can staddle water redox potentials for indium compositions up to 40-50%, corresponding to an energy bandgap ~1.7 eV. This is a unique property not commonly seen in other materials. Significantly, by growing GaN nanostructures under N-rich conditions, the surfaces can be transformed to be N-rich, which can protect against photocorrosion and oxidation during harsh photocatalysis reaction conditions. Studies have further shown that, during the initial solar water splitting reaction, the N-rich surfaces are transformed to be gallium oxynitride, which not only further protects the surfaces of the light absorber but exhibits significantly enhanced photocatalytic and photoelectrochemical performance with continued reaction, which is in direct contrast to the rapid performance degradation of other known light absorbers. We have demonstrated double-junction InGaN/Si photoelectrode that can exhibit solar-to-hydrogen efficiency of 10% with stability over 100 hrs under practical two-electrode measurement conditions. Moreover, we have developed unique photocatalytic process wherein high efficiency solar hydrogen can be produced utilizing tap water, or seawater, without any wire connection, or electricity input. The demonstration of large-scale solar water splitting systems and the performance will be discussed and reported. Moreover, the use of GaN-based photocatalytic nanostructures for converting carbon dioxide and methane to liquid fuels under sunlight will be presented.
Modifying Hybrid Plasmonic Nanocatalysts Via Femtosecond Pulsed Laser for Solar-Fuel-Based Applications
Authors: Nazemi Mohammadreza
Published: November 2022

Harvesting solar energy for chemical transformations is gaining a rising interest in promoting the clean and modular chemical synthesis approach and addressing conventional thermocatalytic systems’ limitations. Under light irradiation, noble metal nanoparticles, particularly those characterized by localized surface plasmon resonance, commonly known as plasmonic nanoparticles, generate a strong electromagnetic field, excited hot carriers, and photothermal heating. The catalytic activity of Plasmonic nanoparticles can be enhanced by incorporating transition metal catalysts as co-catalysts, promoters or stabilizers. In this talk, we demonstrate that by modifying the atomic structure of hybrid plasmonic nanocatalysts via femtosecond pulsed laser we are able to not only enhance the optoelectronic and catalytic properties of the resulting nanoparticles, but also to improve the mechanical stability of these hybrid nanostructures, which are of paramount importance for industrial applications. We also investigate the trade-off between the effect of light absorption, catalytic activity, and mechanical stability by optimizing the structure and composition of hybrid plasmonic nanoparticles. This work provides insight into the design of hybrid plasmonic-catalytic nanostructures with improved performance and stability for solar-fuel-based applications.
(Invited) Hot Electron Generation and Photocatalysis with Plasmonic Nanocrystals and Metastructures
Authors: Govorov Alexander
Published: November 2022

The generation of energetic (hot) electrons and the photoheating are intrinsic properties of any optically excited plasmonic nanocrystal [1,2]. In addition, high-energy hot electrons and phototemperature contribute to the kinetic processes observed in plasmonic photodetectors, colloidal nanocrystals, and metastructures [1,2]. In this talk, we will focus on the theory of hot electron generation and present related applications for plasmonic photochemistry and plasmonic photocatalysis [3,4,5,6].

[1] L. Chang, L. V. Besteiro, J. Sun, E. Y. Santiago, S. K. Gray, Z. Wang, A. O. Govorov, ACS Energy Lett., 4, 10, 2552-2568 (2019).

[2] L. V. Besteiro, P. Yu, Z. Wang, A. W. Holleitner, G. V. Hartland, A. O. Govorov, Nano Today, 27, 120-145 (2019).

[3] T. Liu, L.V. Besteiro, T. Liedl, M.A. Correa-Duarte, Z. Wang, A. Govorov, Nano Letters, 19, 1395–1407 (2019).

[4] L. Khosravi Khorashad, L. V. Besteiro, M. A. Correa-Duarte, S. Burger, Z. M. Wang, A.O. Govorov, J. Am. Chem. Soc., 142, 9, 4193–4205 (2020).

[5] O. Ávalos-Ovando, L.V. Besteiro, A. Movsesyan, G. Markovich, T. Liedl, K. Martens, Zh. Wang, M.A.Correa-Duarte, and A.O. Govorov, Nano Letters (2021); DOI: 10.1021/acs.nanolett.1c02479.

[6] A. Movsesyan, E. Y. Santiago, S. Burger, M. A. Correa-Duarte, L. V. Besteiro, Zh. Wang,andA.O.Govorov, Advanced Optical Materials (2022); https://doi.org/10.1002/adom.202102663.
(Invited) Transient Absorption and Compressive Sensing for Understanding Dynamics in Photocatalytic Nanoparticles and Energy Conversion Materials
Authors: Wiederrecht Gary P.
Published: November 2022

Transient absorption (TA) is a well-known tool for understanding the dynamical response of materials following the absorption of a photon. TA allows the dynamics of photoinduced energy flow and energy conversion to be monitored, along with other competing dissipative processes. With current technologies, TA can provide dynamical information over the ultraviolet, visible, near-infrared, mid-infrared, and terahertz spectral ranges, which allows the study of a concomitant range of photoinduced processes of relevance to photocatalysis. However, since TA usually involves very small changes in absorption, the approach can be quite time consuming and, as a result, signal averaging for hours is not uncommon. In addition to time limitations, long signal averages are challenging for many materials, including photocatalytic systems, because many materials degrade under long periods of laser illumination. Longer experiments also place greater demands on the stability of lasers, usually leading to the need for environmental controls, which adds cost and complexity to TA spectroscopies. Thus, there are several important reasons to increase the speed of TA as long as accuracy and sensitivity can be maintained.

In this talk, I present recent efforts to dramatically decrease the time needed to perform TA through compressive sensing, whereby a smaller number of data points are randomly collected over the chosed dynamical range of the TA experiment.[1] The general principle works well when the transformation of the optical signal to another domain has a low density of TA features. Studies and applications to colloidal plasmonic nanoparticles, such as nanostructures made of refractory materials, and energy conversion materials are shown. I also present imaging efforts using femtosecond optical pulses in scattering environments where conventional imaging is difficult.[2] By utilizing enhanced second harmonic generation from high peak-power ultrashort pulses, combined with compressive sensing approaches, successful reconstruction of optical images can be undertaken.

Work performed at the Center for Nanoscale Materials, a U.S. Department of Energy Office of Science User Facility, was supported by the U.S. DOE, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. This material is based on work supported by Laboratory Directed Research and Development (LDRD) funding from Argonne National Laboratory, provided by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-06CH11357.

References

Adhikari, S., Cortes, C. L., Wen X., Panuganti, S., Gosztola, D. J., Schaller, R. D., Wiederrecht, G. P., Gray, S. K., “Accelerating ultrafast spectroscopy with compressive sensing,” Phys. Rev. Appl., Vol. 15, 024032, 2021.

Wen, X., Adhikari, S., Cortes, C. L., Gosztola, D. J., Gray, S. K., Wiederrecht, G. P., “Ghost imaging second harmonic generation microscopy,” Appl. Phys. Lett., Vol. 116, 191101, 2020.
(Invited) Excited States and Reaction Mechanisms of Catalysts with Redox Active Ligands Investigated with X-Ray Spectroscopy
Authors: Cordones-Hahn Amy
Published: November 2022

Metal dithiolenes and related molecular catalysts known for their redox-active ligands and their efficient and robust electro- and photo-catalysis of the hydrogen evolution reaction are investigated. To understand how the redox-active ligands of these catalysts influence their electronic excited states and participate in their chemical reactions, we need element-specific probes of charge and bonding at both metal and ligand atomic sites. X-ray absorption spectroscopy (XAS) affords us this opportunity and is used to study the electro- and photo-catalytic reaction mechanisms of these complexes, with a specific focus on the role of metal versus ligand atomic sites. Steady-state and time-resolved XAS studies at the Ni and S K-edges will be presented to identify the redox activity of metal vs. ligand sites on timescales spanning from the ultrafast excited state relaxation and photochemical activation processes to the steady-state creation of important intermediates in the multi-step hydrogen evolution reaction.
(Invited) Why Is Pacman so Hungry? Femtosecond M-Edge XANES Explains the Low Quantum Yield of µ-Oxo Bis(Fe Porphyin) Photocatalysts
Authors: Vura-Weis Josh
Published: November 2022

Bridged μ-oxo iron bisporphyrins serve as photocatalysts for oxidative organic transformations, but suffer from low quantum efficiency. This low performance has been primarily attributed to the short lifetime of Fe(II)/Fe(IV)=O state formed after LMCT excitation, but a competing proposal claims that the majority photoproduct is a catalytically inactive ligand-centered ion pair. We use femtosecond optical and M2,3-edge XANES spectroscopy to investigate the early photodynamics of the μ-oxo iron bisporphyrin, (TPPFe)2O, providing evidence for the preferential formation of an TPPFe(III)+/TPPFe(III)-O-
ion pair state instead of the desired TPPFe(II)/TPPFe(IV)=O. This work provides new guidance for catalyst design, suggesting that the excited-state potential surfaces must be redesigned to promote formation of the catalytically active state.
(Invited) Water Splitting and Carbon Dioxide Conversion By Mixed-Anion Materials
Authors: Maeda Kazuhiko
Published: November 2022

Mixed-anion materials that consist more than one anionic species in a single-phase have attracted attention for various applications. Oxynitrides containing d0- or d10-metal cations are typical example of visible-light-driven photocatalysts for water splitting and CO2conversion. In this presentation, recent progress on the development of mixed-anion materials for water splitting and CO2 conversion made by our group will be given.

While two-dimensional (2D) undoped layered oxynitrides are potential candidates as high performance visible-light photocatalysts, synthesis of 2D layered oxynitrides is generally difficult because most of them are metastable phases and are not chemically very stable. We found an exceptional example of a 2D layered oxynitride, K2LaTa2O6N (more specifically, K2LaTa2O6N·1.6H2O), which is a Ruddlesden-Popper phase two-layer perovskite analogous to Li2LaTa2O6N and has a band gap of 2.5 eV. This material undergoes in situH+/K+ exchange in aqueous solution while keeping its visible light absorption capability. The protonated, Ir-modified K2LaTa2O6N exhibited photocatalytic activity for H2 evolution from aqueous NaI solution under visible light, outperforming Pt/ZrO2/TaON and Pt/SrTiO3:Rh, which are one of the best-performing oxynitride and oxide photocatalysts for H2 evolution, respectively.

The use of mixed-anion materials is of interest not only for photocatalysts but also for catalysts promoting water oxidation and CO2reduction. For example, we found that certain oxyfluorides work as electrocatalysts for water oxidation. A 2D perovskite oxyfluoride Pb3Fe2O5F2 exhibits activity for electrochemical water oxidation to O2, which is 8 times more active than a 3D bulk PbFeO2F.
(Invited) Facet-Dependent Photocatalysis for CO2 Reduction
Authors: Rajh Tijana , Wu Yimin , Liu Yuzi
Published: November 2022

Bioinspired artificial photosynthesis has resulted in efficient solutions for many areas of science and technology spanning from solar cells to medicine. Owing to rapid development of synthesis and nanofabrication methods we are able to engineer advanced materials at atomic and molecular levels and assemble them into functional devices. Copper compounds are very promising as photocatalysts with good multielectron transfer properties due to their loosely bonded d electrons. Cu2O is an inexpensive material with near-ideal electronic properties for solar energy conversion into fuels. Importantly, Cu2O shows intrinsic p-type conductivity due to the presence of negative-charged Cu vacancies with one of the lowest electron affinities, identifying Cu2O as an optimal candidate for reduction of CO2. However, crystalline Cu2O is photocathodically unstable and therefore unsuitable for multielectron reductive photocatalysis, unless strong adsorption of the reactants that modifies active sites and kinetically enhances reduction reactions occurs. Herein, we report atomic level understanding of the facet-selective active sites in Cu2O that lead to the discovery of the facet specific adsorption and subsequent light induced reduction of CO2 exclusively into liquid fuel – methanol. The activity of these sites was unraveled using operando multimodal correlated characterization of a single particle, and in situ activity measurements. By employing correlated scanning fluorescence x-ray microscopy and environmental transmission electron microscopy at atmospheric pressure, in operando, on a single particle level, we designed nanoparticles with highly active facet selective active sites and particles activity. We also show the interplay between strain and photocatalytic reaction for CO2 reduction on Cu2O single particles that leads to high yield of facet-selective photocatalytic reduction of CO2 to methanol.
Electrochemical Reduction of Flue Gas CO2 in a Dual Methanol/Water Electrolysis System for the Synthesis of Methyl Formate
Authors: Spurgeon Joshua M. , Hofsommer Dillon , Gautam Manu , Uttarwar Sandesh , Theaker Nolan , Grapperhaus Craig
Published: November 2022

The conversion of waste CO2 to value-added chemicals through electrochemical reduction is a promising technology for mitigating climate change while simultaneously providing economic opportunities. The use of the nonaqueous solvent methanol allows for higher CO2 solubility and novel products through the incorporation of methanol as an intermediate. In this work, the electrochemistry of CO2 reduction in acidic methanol catholyte at a Pb working electrode was investigated while using a separate aqueous anolyte to promote a sustainable water oxidation half-reaction. The selectivity among methyl formate (a product unique to reduction of CO2 in methanol), formic acid, and formate was critically dependent on the catholyte pH, with a faradaic efficiency for methyl formate as high as 75% measured in pH < 2. Furthermore, strategies to limit the concentration of formic acid and maintain the surface oxide of the catalyst have been shown to be effective at improving the steady-state durability of the CO2-to-methyl formate process. Tests with simulated flue gas as the feedstock have shown a high level of tolerance for the Pb-catalyzed electrolysis to SO2, NO, and dilute O2 contaminants. Finally, a comparative technoeconomic analysis will be discussed to highlight target performance metrics and the viability of alternate pathways for electrochemical conversion of CO2 to methyl formate.
(Invited) Controlling Hydrogen Evolution and Oxygen Reduction Electrocatalysis By Tuning Interfacial Hydrogen Bonds
Authors: Zhang Yirui , Wang Tao , Huang Botao , Shao-Horn Yang
Published: November 2022

Designing electrochemical water splitting and its reverse process is crucial for fuel cells to achieve high efficiency. Conventional design of catalysts has focused on tuning the surface electronic structures and binding strength of intermediates, while recent studies show that changing electrolyte compositions, such as cations and pH [1], can also significantly alter catalytic activity, highlighting new opportunities in tuning noncovalent interactions in the electrolytes to control activities.

In the first part of this talk, we use an interfacial layer of protic ionic liquids on platinum and gold to tune the oxygen-reduction reaction (ORR) kinetics, where altering the proton activity of ionic liquids increases the intrinsic ORR activity by up to five times [2]. The maximum enhancement of kinetics is achieved when the pKa of the ionic liquid is comparable to that of the reaction intermediate, which is attributed to the most strengthened hydrogen bonding between the ionic liquid and ORR products, as supported by surface-enhanced infrared absorption spectroscopy (SEIRAS). In the second part, we confine water in an organic matrix and tune the hydrogen-bonding networks as well as hydrogen evolution and oxidation reactions (HER/HOR) kinetics by changing the water concentration (1% - 50% molar ratio) and altering the physical properties (donor number) of organic solvents. Decreasing the water-to-organic ratio, the OH stretching frequency of water shifts to higher wavenumbers, indicating more isolated water, while the water reduction has more negative onset potentials. The shifts in onset potentials are solvent-dependent, highlighting the role of interfacial hydrogen bonds between solvents and water in controlling HER/HOR kinetics. SEIRAS measurements provide further support to the changes in interfacial hydrogen bonding during the reactions.

These findings open up immense opportunities for using noncovalent hydrogen bonding interactions at the electrified interface to control the kinetics of ORR, HER, and beyond. The understanding would also be impactful across other reactions crucial to improving decarbonizing efforts in energy storage, such as CO2 reduction and aqueous batteries.

References

[1] Huang, B., Rao, R.R., You, S., Hpone Myint, K., Song, Y., Wang, Y., Ding, W., Giordano, L., Zhang, Y., Wang, T. and Muy, S., 2021. Cation-and pH-Dependent Hydrogen Evolution and Oxidation Reaction Kinetics. JACS Au, 1(10), pp.1674-1687.

[2] Wang, T. ‡, Zhang, Y. ‡, Huang, B., Cai, B., Rao, R.R., Giordano, L., Sun, S.G. and Shao-Horn, Y., 2021. Enhancing oxygen reduction electrocatalysis by tuning interfacial hydrogen bonds. Nature Catalysis, 4(9), pp.753-762.
Effect of Substrate Microstructure and Hydrophobicity on Ag Gas Diffusion Electrodes for Electrochemical CO2 Reduction
Authors: Senocrate Alessandro , Bernasconi Francesco , Battaglia Corsin
Published: November 2022

Electrochemical CO2 reduction (CO2RR) is a very promising way to convert detrimental CO2 emissions into sustainable fuels and chemicals, and move us closer to a circular economy.1 To compete with traditional fuel/chemical production routes, we need to develop electrocatalysts that are highly active, selectivity towards a desired product, and stable. Thanks to the use of gas diffusion electrodes (GDEs) that provide gaseous CO2 close to the catalyst, high activities can be achieved.2,3 However, product selectivity and stability must still be improved before practical application. An emerging strategy in this regard is to control the local environment surrounding a catalyst, i.e. the concentration of the various products and reagents therein.4 In this work, we achieve such control by varying the microstructure of substrates later used to fabricate GDEs by Ag deposition. By systematically studying the CO2RR performance, we observe a clear correlation between the pore size of the GDEs and their product selectivity, stability, and even resilience to Cu impurities.5 We rationalize it with the different effective hydrophobicity of the GDEs, which control the extent of electrolyte penetration within the electrode and depends on both substrate chemistry and pore size. We show that a higher effective hydrophobicity correlates with higher Faradaic efficiency towards carbon monoxide production (FECO up to 95 % at 100 mA/cm2) and longer stability (~100 % retention after a 1 hour electrolysis at 100 mA/cm2). These results show the importance of the substrate's microstructural properties in GDE for CO2RR, and highlight a new strategy to achieve control over selectivity and stability of these electrodes.

References:

(1) Senocrate, A.; Battaglia, C. J. Energy Storage
2021, 36, 102373.

(2) Verma, S.; Hamasaki, Y.; Kim, C.; Huang, W.; Lu, S.; Jhong, H. R. M.; Gewirth, A. A.; Fujigaya, T.; Nakashima, N.; Kenis, P. J. A. ACS Energy Lett.
2018, 3 (1), 193–198.

(3) García de Arquer, F. P.; Dinh, C.-T.; Ozden, A.; Wicks, J.; McCallum, C.; Kirmani, A. R.; Nam, D.-H.; Gabardo, C.; Seifitokaldani, A.; Wang, X.; Li, Y. C.; Li, F.; Edwards, J.; Richter, L. J.; Thorpe, S. J.; Sinton, D.; Sargent, E. H. Science (80-. ).
2020, 367 (6478), 661–666.

(4) Veenstra, F. L. P.; Ackerl, N.; Martín, A. J.; Pérez-Ramírez, J. Chem
2020, 1–16.

(5) Senocrate, A.; Bernasconi, F.; Battaglia, C. et al.
Submitted
2022.
(Invited) Reversible Solid Oxide Electrochemical Cells for Grid Scale Storage of Renewable Energy
Authors: Akter Ayesha , Banner Jane , Gopalan Srikanth
Published: November 2022

Incorporating more renewables into our energy mix is the central challenge that confronts our transition to a carbon free economy. Reversible solid oxide electrochemical cells (rSOCs) when operated alternately as fuel cell power systems and as electrolysis systems, enable the incorporation and integration of far greater amounts of solar and wind energy into our power grid. As standalone systems, they can also function as distributed generation systems thereby decreasing our reliance on the power grid. In this talk, we present recent results on rSOCs based on rare earth nickelate – rare-earth doped ceria composite oxygen electrodes that exhibit excellent cycling behavior when operated reversibly in solid oxide fuel cell (SOFC) and solid oxide electrochemical cell (SOEC) modes of operation. The degradation in such cells is significantly mitigated by mode-switching operation when compared to operating in single mode operation in electrolysis mode. By comparing distributed relaxation times (DRT) analysis of impedance spectra obtained from single-mode (electrolysis) operated cells, and cells operated in switched-modes, we obtain clues into cell degradation mechanisms.
(Invited) Understanding and Mitigating Chemo-Mechanical Degradation in Solid Oxide Cells
Authors: Lim Hyung-Tae
Published: November 2022

Solid-state electrochemical cells may undergo significant chemical potential changes in the electrolyte region near the electrodes, depending on operating conditions. Lithium dendrite growth, which may eventually induce mechanical stresses and short circuit in all-solid-state batteries (SSBs) in the charging process, is one of the well-known examples representing chemo-mechanical failure in solid-state electrochemical cells [1, 2]. A similar phenomenon has been observed in solid oxide cells (SOCs) operated in electrolysis mode and also in fuel cell mode with a negative voltage [3, 4]. Contrary to lithium precipitation in SSBs, high partial pressure of oxygen is developed in SOCs, resulting in electrode/electrolyte delamination. In the present study, we investigated the mechanism of delamination growth in SOCs with respect to operating conditions, based on which we determined a critical factor correlated to mechanical failure. This study provides basic understanding and critical insights into the chemo-mechanical failure mechanism of SOCs with respect to operating conditions.

References

[1] S. Ohno, R. Koerver, G. Dewald, C. Rosenbach, P. Titscher, D. Steckermeier, A. Kwade, J. Janek, W.G. Zeier, Chem. Mater., 31 (8) (2019), pp. 2930-2940

[2] M. Otoyama, M. Suyama, C. Hotehama, H. Kowada, Y. Takeda, K. Ito, A. Sakuda, M. Tatsumisago, A. Hayashi, ACS Appl. Mater. Interfaces, 13 (4) (2021), pp. 5000-5007

[3] H.-T. Lim, A.V. Virkar, J. Power Sources, 185 (2008), pp. 790-800

[4] B.-K. Park, Q. Zhang, P.W. Voorhees, S.A. Barnett, Energy Environ. Sci., 12 (2019), pp. 3053-3062
A Highly Performing Electrode with in-Situ Exsolved Nanoparticles for Direct Electrolysis of CO2
Authors: Park Ka-Young , Lee Taehee , Wang Wanhua , Li Haixia , Chen Fanglin (Frank)
Published: November 2022

Carbon dioxide (CO2) emissions have increased continuously and rapidly since the industrial revolution, contributing to the serious greenhouse effect and leading to global warming. To minimize this effect, more attentions have been devoted to convert CO2 into useful chemicals such as carbon monoxide (CO), methane, methanol and dimethyl ether through sustainable, renewable, and alternative energy sources while lowering the dependence on fossil fuels. Although various technologies for CO2 conversion have been employed, such as thermocatalytic, electrochemical, and photochemical reductions, the conversion of CO2 to valuable products is relatively difficult due to its remarkably stable C=O bonds. Among them, the electrochemical reaction has a better possibility than the others because the electrochemical reaction is controllable and can utilize alternative energy sources for CO2 conversion, potentially achieving a carbon-neutral energy cycle.

As an efficient energy storage method, several types of electrolysis cells have been studied to reduce CO2 electrochemically. Due to the advantages of high energy efficiency, good stability, and high faradaic efficiency, solid oxide electrolysis cells (SOECs) are more promising for practical applications in the future than the other electrolysis cells. One challenge is to develop high-performance CO2 conversion electrode, which should possess high catalytic activity, electronic and ionic conductivity, chemical stability in the CO2 atmosphere, and good resistivity against carbon deposition. Cermets (e.g., Ni-YSZ) have been utilized as a traditional CO2 conversion electrode for SOECs because Ni metal serves as not only the electrocatalyst but also the electronic conductor. However, the cermets have issues for CO2 electrolysis due to the oxidation of Ni metal and carbon coking when exposed to a pure or concentrated CO2 atmosphere. Therefore, mixed ionic-electronic conducting (MIEC) perovskites have been investigated as the potential cathode materials for CO2 electrolysis, which should have high enough electrical conductivity and chemical stability in the CO2 atmosphere.

Perovskites have been considered attractive catalytic materials in the fields of solid oxide fuel cells due to their acceptable electrical conductivity and coking resistance. However, these perovskites have shown relatively low catalytic activity compared to Ni-YSZ cermet. In this work, a novel perovskite has been developed by introducing active nanoparticles via an in situ exsolution process, which showed high performance for the conversion of CO2 to CO. Its electrical conductivity and chemical stability in operating conditions for CO2 electrolysis have been systematically evaluated.

Acknowledgements

Financial support from the U.S. Department of Energy (DE-EE0009427) is greatly appreciated.
Scalability of Protonic Ceramic Electrochemical Cell for Industrial Applications at Idaho National Laboratory
Authors: Gomez Joshua , Wu Wei , Feng Wuxiang , Zhao Zeyu , Wang Lucun , Ding Hanping , Ding Dong
Published: November 2022

Novel protonic ceramic electrochemical cells (PCECs) are manufactured and tested at Idaho National Labs with the intention of scaling these materials for industrial application and market penetration. The focus of the presented work is to develop methodologies that can be used to translate the novel research executed at INL to industrial manufacturing and testing. The appeal to invest effort toward PCEC technology stems from a favorable efficiency, high proton conductivity, and low activation energy at operating temperatures between 400-600°C leading to greater performance and better durability than oxygen conducting solid ceramic electrochemical cells with the promise to reduce the cost. The challenge with PCEC arises from obstacles in the materials that project concerns of unreliability. Presently these concerns are being addressed at INL by implementing robust quality management (QA/QC) methodologies to ensure repeatable and reproducible fabrication, data, and results. From raw power supply to utilize conventional ceramic manufacturing and power spray coating to the design of PCEC, we successfully transitioned from 10 mm and 1” button to planer 5x5cm, and 10x10cm cells. The PCEC have been long term tested for 1000 hours under electrolysis conditions at 600°C resulting in a current density of -0.7 A/cm2 operated at 1.3V. The outcomes of these efforts effectively demonstrate that manufactured PCEC technology can successfully contribute to the increasingly diversifying energy portfolio of global economies that are beginning to invest in green hydrogen production as well as flexible chemical manufacturing pathways (e.g. CO2 conversion and ammonia synthesis).
Interfacial Engineering of Protonic Ceramic Electrochemical Cells By Acid Etch
Authors: Bian Wenjuan , Wu Wei , Tang Wei , Dong Yanhao , Li Ju , Ding Dong
Published: November 2022

The ceramic proton conductors (e.g. BaZr0.1Ce0.7Y0.1Yb0.1O3−δ, noted as BZCYYb) in protonic ceramic electrochemical cells (PCEC) exhibit high ionic conductivity at reduced temperature due to lower activation energy. However, high sintering temperature (≥1400 oC for BZCYYb, ≥1500 oC for BaZr0.8Y0.2O3−δ) was required to densify these ceramic electrolytes during fabrication. The formation of well-annealed electrolyte surface because of the high sintering temperature leads to poor bonding between the electrolyte with oxygen electrode. Here, we proposed a novel and simple acid treatment method to rejuvenate protonic ceramic electrolyte surface. The acid etching process was after the full sintering of half-cell at 1400 oC. 0.3 mL concentrated nitric acid was used to etch the surface of dense electrolyte (for 10 mm button cell) before integration with oxygen electrode. We observed the obvious electrochemical performance improvements with different oxygen electrodes including PrNi0.5Co0.5O3−δ, La0.6Sr0.4Co0.2Fe0.8O3−δ, PrBa0.5Sr0.5Co1.5Fe0.5O5+δ and even with Pt or Ag electrode after acid etching. Large cells (5×5 cm2, 10×10 cm2) with electrolyte treated by nitric acid was prepared and showed enhanced electrochemical performance as well.
Novel Catalyst for Methane Reforming to Synthesize Syngas and Its Application in Solid Oxide Fuel Cell
Authors: Wu Wei , Bian Wenjuan , Wang Lucun , Li Meng , Tang Wei , Ding Dong
Published: November 2022

The importance of methane reforming reactions is increasing due to the climbing demand of H2 and synthesis gas, which is the major feedstock for C1 chemistry and fuel cells. Reforming of methane with water or carbon dioxide is an important technology for the conversion of CH4 to H2 and syngas as chemical raw materials and fuel gas of solid oxide fuel cells. Herein, we invented a novel Pr-doped Ni/CeO2 catalyst for methane reforming with high activity and excellent coking-tolerance ability. The integration of this catalyst in a SOFC enables the direct utilization of nearly dry methane as the fuel with high electrochemical performances as well as significantly improved durability compared to the SOFC without the catalyst.
Effects of Electronic and Ionic Conductivities of Layered Perovskites on Solid Oxide Electrolyser Performances
Authors: Jang Inyoung , Kelsall Geoff H
Published: November 2022

The climate change crisis is causing an exponentially increase in demand for green hydrogen. When run in electrolysis mode, solid oxide electrochemical reactors (SOERs) are one of the systems that can generate green hydrogen with high efficiencies, due to their high operating temperatures. In SOERs, the rate-determining steps for the overall reaction come from oxygen reduction (ORR) in fuel cell mode and oxygen evolution (OER) in electrolyser mode. For the enhancement of catalytic activity for ORR/OER, recent studies have been focused on layer perovskite materials for positive electrodes to increase SOER performances. The distinctive arrangement of cations in their structures leads to higher oxygen vacancy concentrations, thereby promoting catalytic activity for ORR/OER.

We shall report OER kinetics of two layered perovskites: PrBaCo1.6Fe0.4O5+δ (PBCF) and NdBaCo1.6Fe0.4O5+δ (NBCF) which have been studied as materials exhibiting major differences in oxide ion and electronic conductivities. Electrolyser performances were determined of both water vapour (→2H2 + O2) and CO2 (→2CO + O2), on which the effects were investigated of those differences in ionic / electronic conductivities. For water vapour electrolysis at the thermoneutral potential difference of 1.285 V, the current density was 144 mA cm-2 at 700 ℃ for the cell with a PBCF positive electrode, which exhibited current densities 1.42 times higher than for the cell with a NBCF positive electrode, for reasons we shall explain.
A Solid Oxide Electrolysis Cell (SOEC) with High Current Density and Energy Efficiency for Hydrogen Production
Authors: Adjah-Tetteh Christabel , Wang Yudong , Sun Yanhua , Jia Zhiyong , Yu Xingwen , Zhou Xiao-Dong
Published: November 2022

Water splitting with solid oxide electrolysis cells (SOECs) has gained increasing attention as an efficient, affordable, and sustainable technology for hydrogen production. Since electricity represents the bulk of projected hydrogen cost for operating SOECs, enhancing the utilization efficiency of electricity (electrochemical energy efficiency) is critical to reach the cost-effective milestone for cell/electrolyzer development. In this study, we present a SOEC design with an ultra-thin solid electrolyte (based on an yttria-stabilized zirconia material) layer as well as an electrode support layer with reduced thickness to minimize the cell resistance. The thin electrolyte and electrode-support layers were fabricated with our optimized tape casting process. In addition to reducing the cell resistance, the implementation of thin electrolyte and electrode-support layers offers a facile and short path for gas diffusion, which can reduce the efficiency loss caused by diffusion. With our optimized cell configuration design, a high electrolysis current density was achieved at 750 oC. Over the process of cell-configuration optimization, electrochemical impedance spectroscopy (EIS) and microscopic analysis were systematically performed on the cell and cell components to rationalize the cell architecture toward accessing high electrochemical performance and high energy efficiency of the SOEC. The relevant analysis strategies and results will be presented as well.
High Power Density Automotive Membrane Electrode Assemblies
Authors: Jones Deborah J. , Zaton Marta , Rozière Jacques , Cavaliere Sara , Buche Silvain , Sharman Jonathan , M. Bonastre Alejandro , Hodgkinson Adam , Nesling Emily , Albert Albert , Finkenwirth Olav , Zink Stefan , Brimaud Sylvain , Joerissen Ludwig , Barsch Hannes , Muggli Mark , Ponomarev Ivan , Spackova Martina , Gasteiger Hubert Andreas , Weber Konstantin , Loichet Paulette A. , Strasser Peter , Dionigi Fabio , Pan Lujin
Published: November 2022

The European GAIA project focussed on the development of novel ionomer, membrane, reinforcement, catalyst, catalyst support, gas diffusion and microporous layers, and layer constructions for high power density, high current density automotive membrane electrode assemblies (MEAs). Reaching a sufficiently low degradation rate (11-14 µV/h in an automotive drive cycle including operation at 105 °C) consistent with the 6,000 hour lifetime target while also succeeding in achieving the 1.8 W/cm2 power density at high current density (3 A/cm2) target was a major challenge, and the outcomes of GAIA represent an important step forward for fuel cell transport MEA technology. The results are all the more important that they were obtained with MEAs using materials developed and up-scaled in GAIA. By reaching this high-power density without increasing platinum loading, the Pt-specific power density was reduced to 0.25 g Pt/kW. Costs analysis demonstrated that recycling (catalyst and ionomer) has the potential to significantly reduce MEA cost, and that, with this, the cost per kW of the high power density GAIA MEAs approaches the 6 €/kW target. This presentation will outline the main materials development steps, summarise testing protocols and the results of automotive size cell short stack tests.

Acknowledgement. This project has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking (now Clean Hydrogen Partnership) under grant agreement n°826097. This Joint Undertaking receives support from the European Union’s Horizon 2020 Research and Innovation program, Hydrogen Europe and Hydrogen Europe Research.
(Invited) Advancing Human-Centric Lighting
Authors: Brgoch Jakoah , Hariyani Shruti
Published: November 2022

The concept of human-centric lighting stems from the evolution of sunlight’s intensity and color temperature throughout the course of a day. This natural progression of bright cold-white light during the middle of the day to a softer warm-white light in the evening stimulates intrinsic photosensitive retinal ganglion cells that control our circadian rhythm. The blue-hue of daylight activates these cells to produce dopamine and cortisol while suppressing melatonin, the sleep hormone, to keep humans awake and alert. The current generation of energy-efficient LED lights reproduce daylight by converting a blue-emitting LED into a broad-spectrum white light using inorganic phosphors. Unfortunately, the resulting intense blue-hue generated by cheap LED bulbs and the underlying blue light from even the most expensive bulbs have been shown to cause macular degeneration, cataract formation, mood disorders, and circadian disruption, resulting in insomnia and fatigue. This talk will investigate the production of a ‘human-centric’ light that minimizes blue light by using a violet LED chip and inorganic phosphors. We report a new phosphor, Na2MgPO4F:Eu2+, which can be readily excited by violet light to produce a bright blue emission. This material possesses all the necessary requirements for LED lighting, including a high quantum yield, thermally robust emission, and impressive chemical stability. Incorporating this material into a prototype device demonstrates our ability produce a warm-white light with a higher color rendering index than a commercially purchased LED light bulb while significantly reducing the blue component.
Molecular (photo)Electrochemical Reduction of CO2 to C1 Products with 2, 4, 6 and 8 Electrons from Mechanistic Studies to Hybrid Systems and Devices
Authors: Robert Marc
Published: November 2022

Reduction of carbon dioxide has as main objective the production of useful organic compounds and fuels - renewable fuels - in which solar energy would be stored. Molecular catalysts can be employed to reach this goal, either in photochemical or electrochemical (or combined) contexts. They may in particular provide excellent selectivity thanks to easy tuning of the electronic properties at the metal and of the ligand second and third coordination sphere. Recently it has been shown that such molecular catalysts may also be tuned for generating highly reduced products such as methanol and methane, leading to new exciting advancements.

Hybridization of these catalysts with conductive or semi-conductive materials may lead to enhance stability and new catalytic properties, as well as inclusion of molecular catalysts in devices for applications. This approach bridges between homogeneous and heterogeneous, and it raises new fundamental questions that may further lead to breakthrough in CO2 reduction chemistry.

Our recent results in these various areas will be discussed, using earth abundant metal (Fe, Co) porphyrins and phthalocyanines as well as related complexes as catalysts.

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