bluuebunny/crossref_metadata_2025 huggingface dataset:
Manufacture and Performance of 3D Printed Carbonised Gas Diffusion Layers
Authors: Niblett Daniel , Guo Zunmin , Niasar Vahid J. , Holmes Stuart , Prosser Robert
Published: July 2022

Proton exchange membrane fuel cells (PEMFC) electrochemically combine hydrogen and oxygen to produce electrical energy, heat and water. Therefore, PEMFC offer an alternative to vehicle electrification and reduction of greenhouse gas emissions. However, material limitations under high current density conditions limit the efficiency due to water flooding subsequent mass transport overpotential.

The cathode gas diffusion layer of PEMFC is conventionally a carbon paper material, due to its high electrical conductivity, permeability and mechanical strength. Whereas the porosity and thickness can be controlled, the exact microstructural features are unknown, resulting from the web of randomly orientated fibres. If the microstructural features of the porous layer can be designed, improvements in water flooding and mass transport could be established.

This research talk focuses on the series of studies from concept, simulation and manufacturing of designed microstructures using 3D printing and carbonisation. We investigate the potential improvements to electrical/thermal conductivity, permeability and reduction in the saturation using computational fluid dynamics. Furthermore, the impact of the porous microstructure in a lab scale set up is replicated to understand the effects of under-rib convection and oxygen consumption at the catalyst layer.

With a readily available 3D printing method, prototype materials; resembling those evaluated in the simulation studies are manufactured and carbonised into glassy carbon microstructures. The morphology of carbon was limited by the maximum temperature of the furnace. The resulting structures have in-plane dimensions of 2 cm x 2 cm and through-plane between 400 – 800 µm. They were tested for electrical conductivity with a value of approximately 130 S m-1.

Through a controlled carbonisation process, structural damage was minimised and the structures were introduced into a membrane electrode assembly (MEA) via spraying and hot pressing. The resulting MEA was tested in a lab cell to understand further considerations that limit the correct implementation of the 3D printed layers. In-homogenous MPL and CL formation along with membrane cracking are hypothesised to be causes of overpotentials.

Figure 1 – Design process of simulation to manufacture, with simulations of (a) electrical potential, (b) water flooding and (c) oxygen distribution in a designed carbon microstructure. (d) and (e) optical microscope images of printed precursor material and final carbonised structures.

Figure 1
Atomically Dispersed Single Metal Sites for Promoting Pt and Pt3Co Catalysts in Heavy-Duty Meas
Authors: Zeng Yachao , Zhi Qiao , Wang Chenyu , Li Chenzhao , Xu Hui , Cullen David A. , Myers Deborah J. , Xie Jian , Spendelow Jacob S. , Wu Gang
Published: July 2022

Significantly reducing platinum group metal (PGM) loading while improving catalytic performance and durability is critical to accelerating proton-exchange membrane fuel cells (PEMFCs) for transportation. Here we report an effective strategy to boost PGM catalysts through integrating PGM-free atomically-dispersed single metal active sites in the carbon support toward the cathode oxygen reduction reaction (ORR). We achieved uniform and fine Pt nanoparticle (NP) (∼2 nm) dispersion on an already highly ORR-active FeN4 site-rich carbon (FeN4–C). Furthermore, we developed an effective approach to preparing a well-dispersed and highly ordered L12 Pt3Co intermetallic nanoparticle catalyst on the FeN4–C support. DFT calculations predicted a synergistic interaction between Pt clusters and surrounding FeN4 sites through weakening O2 adsorption by 0.15 eV on Pt sites and reducing activation energy to break O–O bonds, thereby enhancing the intrinsic activity of Pt. Experimentally, we verified the synergistic effect between Pt or Pt3Co NPs and FeN4 sites, leading to significantly enhanced ORR activity and stability. Especially in a membrane electrode assembly (MEA) with a low cathode Pt loading (0.1 mgPt cm−2), the Pt/FeN4–C catalyst achieved a mass activity of 0.451 A mgPt
−1 and retained 80% of the initial values after 30 000 voltage cycles (0.60 to 0.95 V), exceeding DOE 2020 targets. Furthermore, the Pt3Co/FeN4 catalyst achieved significantly enhanced performance and durability concerning initial mass activity (0.72 A mgPt
−1), power density (824 mW cm−2 at 0.67 V), and stability (23 mV loss at 1.0 A cm−2). The approach to exploring the synergy between PGM and PGM-free Fe–N–C catalysts provides a new direction to design advanced catalysts for hydrogen fuel cells and various electrocatalysis processes.
Durable and High-Power Iron-Based Cathodes for Proton-Exchange Membrane Fuel Cells
Authors: Liu Shengwen , Li Chenzhao , Xie Jian , Litster Shawn , Cullen David A. , Zachman Michael J. , Myers Deborah J. , Wu Gang
Published: July 2022

Atomically dispersed and nitrogen-coordinated single iron sites (FeN4) embedded in carbon (Fe-N-C) catalysts are the most promising platinum group metal (PGM)-free catalysts. However, they have yet to match their Pt counterparts for oxygen reduction reaction (ORR) activity and stability in proton exchange membrane fuel cells (PEMFCs). Here, we developed viable Fe-N-C catalysts, which, for the first time, demonstrated competitive activity to that of Pt/C catalysts and dramatically enhanced stability and durability under practical PEMFC operating conditions. The most active Fe-N-C catalyst achieved a record half-wave potential (E1/2 = 0.915 V vs. RHE at 0.6 mgcatcm-2) and an ORR mass activity of 10.5 mA mgcat at 0.9 V in (RDE) tests, exceeding a Pt/C baseline catalyst (60 µgPt cm-2) by 40 mV in acidic electrolytes. This compelling activity of the Fe-N-C catalyst in aqueous acids on rotating disk electrode (RDE) was successfully transferred to a fuel cell membrane electrode assemblies (MEAs), generating an initial current density of 44.2 mA cm-2 exceeding the U.S. DOE 2025 target (i.e., 44 mA cm-2) at 0.9 VIR-free under O2. Under practical hydrogen-air conditions, record 151 mA cm-2 at 0.8 V and peak power density of 601 mW cm-2 were achieved. Importantly, we discovered that depositing nitrogen-carbon species on the catalyst surface via chemical vapor deposition (CVD) dramatically enhanced catalyst stability, evidenced by performance durability after accelerated stress tests (30 000 square-wave voltage cycles under H2/air) and long-term steady-state life tests (> 300 hours at 0.67 V). Innovative identical location-scanning transmission electron microscopy (IL-STEM) experiments confirmed that the CVD process leads to deposition of nitrogen-doped carbon onto the catalyst surfaces. Along with theoretical modeling, a reconstruction of the carbon structure adjacent to FeN4 sites leads to increased robustness against demetallation and carbon oxidation. This work opens new avenues for developing earth-abundant iron-based catalysts with extraordinary activity and stability, thus competing with Pt and addressing the cost barrier of current PEMFCs.
(Invited) Understanding the Electrocatalytic Mechanisms of Oxygen and Carbon Dioxide Reduction Reactions
Authors: Liu Di-Jia
Published: July 2022

Oxygen reduction reaction (ORR) is one of the most important reactions in the field of electrocatalysis today. ORR represents a key cathodic reaction in hydrogen fuel cell, which typically needs to be promoted by the platinum group metals (PGMs), particularly Pt. The high cost of Pt adds significant barrier to the widespread implementation of the fuel cell technology. During the last two decades, substantially amount of effort has been invested in searching for low-cost replacements, or PGM-free catalysts for ORR. Although significant progress has been made, such catalysts still face major challenge in durability. By adding small amount of Pt over PGM-free catalytic substrate, we have found that both activity and stability will be significantly improved through synergistic interaction. [1] To better define synergistic effect in ORR catalysis, however, requires a carefully designed experiment that can separates multiple factors during the catalyst synthesis that can potentially influence the overall activity. In this report, we will discuss our recent study in understanding of the ORR catalysis synergy between Pt/PGM-free components in rationally designed catalyst systems.

Another fast developing area of electrocatalysis is CO2 reduction reaction (CO2RR), which promises to electrochemically convert CO2 to fuels and chemicals using renewable electricity. While CO2RR via 2-electron transfer, such as the conversion to CO or formate, has been proven high selective with fast kinetics, conversions to C2+ chemicals require significantly stronger binding between the catalytic site and CO2 to complete multiple electron transfers (8 to 16) and C-C bond coupling steps, therefore are more challenging. More recently, we develop a new amalgamated lithium metal (ALM) synthesis method to preparing highly selective and active CO2RR catalyst for C2+ chemicals such as ethanol production. [2] In this presentation, we will discuss the hypothesis driven CO2RR catalyst design, combined with the mechanistic study for preparing effective catalysts. We will also share some critical insight on CO2RR mechanism through advanced structural characterization and computational modelling.

Acknowledgement: This work is supported by U. S. Department of Energy, Hydrogen and Fuel Cell Technologies Office through Office of Energy Efficiency and Renewable Energy and by Office of Science, U.S. Department of Energy under Contract DE-AC02-06CH11357.

[1] L. Chong, J. Wen, J. Kubal, F. G. Sen, J. Zou, J. Greeley, M. Chan, H. Barkholtz, W. Ding, and D.-J. Liu, “Ultralow-loading Platinum-Cobalt Fuel Cell Catalysts Derived from Imidazolate Frameworks,” Science (2018) 362, 1276

[2] “Highly selective electrocatalytic CO2 reduction to ethanol by metallic clusters dynamically formed from atomically dispersed copper” Haiping Xu, Dominic Rebollar, Haiying He, Lina Chong, Yuzi Liu, Cong Liu, Cheng-Jun Sun, Tao Li, John V. Muntean, Randall E. Winans, Di-Jia Liu and Tao Xu, (2020) Nature Energy, 5, 623–632
CO2 Reduction to Formate By Efficient Bismuth Metal-Organic Framework (TAL33) Based Catalyst
Authors: Assafrei Jurgen-Martin , Kongi Nadezda , Cepitis Ritums , Starkov Pavel , Alam Mahboob
Published: July 2022

The production of various green fuels and valuable chemicals from the electrocatalytic reduction of CO2, is gaining popularity as a method of CO2 removal and utilization. Out of the multitude of possible chemicals that can be produced by CO2 reduction, formate/formic acid shows the most promise, because of its various applications in hydrogen storage, chemical industry and in agriculture. Herein, we report the preparation method for a sustainable electrocatalyst for CO2 reduction into formate/formic acid. The bismuth based catalysts were prepared from affordable metal-organic-framework precursor called TAL-33. The samples prepared with the optimized carbonization temperature showed high Faradaic efficiency and durability, with very little loss of activity during the stability testing. To prove that the presence of metallic bismuth nanoparticles enhances the electroreduction of CO2 to formate, theoretical studies were conducted. DFT studies validated that indeed the presence of metallic bismuth sites are linked to the high selectivity of the catalysts.
Design of M-N-C Catalyst By Spray Pyrolysis and Pseudomorphic Transformation As Efficient Electrocatalysts for Oxygen Reduction Reaction
Authors: Yim Kyungmin , Yoo Sung Jong , Kim Jinsoo
Published: July 2022

Transition metal catalysts with Metal-N-C (M-N-C) sites has been investigated as an alternative of the noble metal catalyst for the oxygen reduction reaction (ORR), which occurs on a cathode of fuel cell. Among the methods of preparing various M-N-C catalysts, carbonized metal organic frameworks (MOF) are the one of the simple ways to synthesize nitrogen-doped carbon. MOF are known highly porous crystalline solids constructed from metal ions or clusters covalently linked by organic ligands. The tunability of their composition, architecture, and properties has has led to advances in drug delivery, catalysis, sensors, optoelectronics, electrochemistry, gas separation and gas adsorption. Although many studies have been reported that M-N-C catalysts have better performance than Pt catalysts, but most have been reported in alkaline media, and Fe-N-C catalysts have been mainly studied in acidic media. Fe-N-C catalysts have excellent performance; the new M-N-C catalyst should be replaced as it is less stable due to the fenton reaction. In this study, we report the synthesis of a melamine-encapsulated Co-ZnO-C composite as a precursor and template for zeolite-imidazole-frameworks (ZIF-8). This approach allows formation of Co-N-C for constructing unique structures at meso- and macropore scales, while maintaining microporosity. Density functional theory analysis confirms the superior stability of the Co-N-C catalyst over other M-N-C catalysts (M = Fe, Ni, Cr, and Mn). The Co-NC catalyst with a developed pore structure shows remarkable durability (6.7 % performance degradation for 100 h) and full cell performance in H2/O2 under 1 bar of backpressure (723 mW/cm2 of maximum power density).
Ionomer Dispersion for IrO2 Based Oxygen Evolution Reaction Electrode with for Decal Process Application
Authors: Park Jong Hyeok , Kim Beom-Seok , Park Jin Soo
Published: July 2022

Green hydrogen production is of importance in the upcoming hydrogen economy era. Proton exchange membrane (PEM) water electrolysis is one of the most important technology to produce the green hydrogen, which requires only water and extra electricity supplied from renewable energy. Main component, i.e., membrane electrode assembly (MEA), is a key part consisting of polymer electrolyte membrane and two electrodes which are oxygen evolution reaction (OER) electrode and hydrogen evolution (HER) electrode. Both electrode should be coated on the surface of membranes for better performance and mass production. HER could be coated by spraying or decal processes since Pt/C electrocatalysts allow to be dispersed in diluted (for spraying) and concentrated (for decal) catalyst inks. However, OER electrode mainly uses IrO2 black electrocatalyst which only allows diluted catalyst inks due to low surface area of IrO2. Thus, OER is generally coated by a spray method. For a decal process for OER electrode, high concentration or high viscosity of catalyst ink should be prepared. In this study, high viscosity ionomer dispersions were prepared using commercially available ionomer dispersions in water and alcohol mixture by substituting water and alcohol solvents into high viscosity solvent (propylene glycol in this study). High viscosity solvent-based ionomer dispersion was investigated for high concentration or high viscosity catalyst ink. The OER electrodes using high viscosity ionomer dispersions were evaluated by electrochemical characterization such as I-V polarization and activation rate.

Acknowledgment

This research was supported in part by the Hydrogen Energy Innovation Technology Development Program of the National Research Foundation (NRF) funded by the Ministry of Science, ICT ＆ Future Planning (NRF-2019M3E6A1063677) and by 2021 Green Convergence Professional Manpower Training Program of the Korea Environmental Industry and Technology Institute funded by the Ministry of Environment.
Performance Prediction of Alkaline Fuel Cell Via Gradient Boosting Algorithm
Authors: Park Jihyeon , Lee Jaeyoung
Published: July 2022

With the DFT theory at the forefront, non-PGM catalysts have begun to develop, and in much literature, results have shown that the performance of non-PGM catalysts is comparable to that of PGM catalysts. Jing et. al. synthesized Fe-Co dual sites on nitrogen-doped carbon for oxygen reduction reaction (ORR). (FeCo)/N-C had almost equal half-wave potential to commercial Pt/C.[1] Hanguang et. al. achieved high ORR-activated Fe-N-C catalysts by tuning the doped Fe content and active sites.[2] However, if both (FeCo)/N-C and Fe-N-C were applied to PEMFC, they were not comparable to PGM catalysts unlike in the results of the half-cell test. This discrepancy means that numerous factors should be considered and optimized in a practical system like a fuel cell. Besides, it is indicated that even if the DFT theory and deep-learning combine to suggest catalysts with high performance, it may not produce as much performance in the actual fuel cell system as expected.

In this respect, the combination of fuel cell systems (not catalysts) and artificial intelligence (AI) seems more reasonable. Without human judgment or intervention, machine learning sets priorities between each index by learning from many databases.

Herein, we newly developed an optimization model for alkaline liquid fuel cell (Hydrazine fuel cell) using gradient boosting algorithm (XGBoost) which is one of machine learning algorithms. We operated fuel cells in various conditions by changing humidity of cathode, back pressure of cathode, cell temperature, stoichiometric factor (air/fuel), and concentration of the fuel. And then, we categorized and classified with the specific algorithm. Finally, we re-organized and set as a function of weight which effects on fuel cell operation. We hope that these approach will help improve fuel cell performance by controlling a number of factors without human intervention.

[1] J. Wang, Z. Huang, W. Liu, C. Chang, H. Tang, Z. Li, W. Chen, C. Jia, T. Yao, S. Wei, Y. Wu, Y. Li, J. Am. Chem. Soc. 139 (2017) 17281–17284.

[2] H. Zhang, H.T. Chung, D.A. Cullen, S. Wagner, U.I. Kramm, K.L. More, P. Zelenay, G. Wu, Energy Environ. Sci. 12 (2019) 2548–2558.
Functionalized and Chemically Exfoliated Molybdenum Oxide Nanosheets As Hybrid Electrodes for High Energy Density Supercapacitors
Authors: Elgendy Dalia , K. Allam Nageh , El Sawy Ehab
Published: July 2022

Energy storage systems are critical for regulating and implementing intermittent renewable resources. In addition, the fast development of energy storage systems accelerated the development of electric vehicles. Supercapacitors' unique properties such as high energy storage, high power output, and varied operational range shall allow them to close the gap between batteries and conventional capacitors.1 In the last few decades, enormous efforts were exalted to enhance the supercapacitors' performance by developing new electrode materials that have a structure with an easy ion diffusion path and a high electrochemical surface area.2

In this work, modified molybdenum oxide (MoOx) nanocomposites have been prepared using a facile hydrothermal-aided process, resulting in 3-dimensional (3D) crumpled MoOx nanosheets intercalated with sulfanilamide (SA) or Adenine (Ad). The intercalation of SA or Ad prevented the aggregation of the MoOx nanosheets and allowed the diffusion of electrolyte ions into the MoOx layers. The synthesized MoOx nanocomposites electrodes exhibited a high specific capacitance at 2 A/g and high stability at 10 A/g over 3000 cycles. The assembled symmetric supercapacitor device consisting of MoOx nanocomposites delivered specific energy and specific power of 66.74 Wh/kg and 3 kW/kg, respectively at 3 A/g, demonstrating a high potential for use in constructing high-performance supercapacitors.

References:

F. Naseri, S. Karimi, E. Farjah, and E. Schaltz, Renewable and Sustainable Energy Reviews, 111913 (2021).

J. Zhao and A. F. Burke, Journal of Energy Chemistry, 59, 276–291 (2021).
Lignin-Based N-Doped Nanocarbons for the ORR
Authors: Kaare Kätlin , Kruusenberg Ivar , Volperts Aleksandrs , Dobele Galina , Zhurinsh Aivars
Published: July 2022

Fuel cells (FC) are one of the most viable energy conversion devices that could replace fossil-fuel based energy production in the future. As the oxygen reduction reaction (ORR) happening at the cathode side has slow kinetics, the usage of catalysts that speed up the process is inevitable. Most of the studied catalyst materials include precious metals or their alloys. Lately, the conversion of biomass to carbon nanomaterials and the usage of biomass-based carbons in different energy conversion systems has grown enormously [1].

Lignin among the major components of lignocellulosic biomass, which is mainly produced in the pulp and paper industry or in biorefineries. To fully unlock the potential of biorefineries, the components of lignocellulosic biomass (e.g. lignin, hemicellulose, cellulose) must be fractionated and valorized [2]. Currently, lignin is used to produce electricity and heat in factories or landfilled. Since the main component of lignin is carbon, it is possible to synthesize lignin-based carbon nanomaterials.

In this work, lignin from a local Estonian biorefinery was used to produce high specific surface area nanocarbons that were studied as catalysts for the ORR. Different ways (two-step or one-step) and temperatures (700 or 800 °C) were used to carry out the carbonization and activation processes. In the second step, dicyandiamide was used to carry out the nitrogen doping at 800 °C. Electrochemical characterization of the N-doped industrial lignin-based carbon catalysts were carried out by employing rotating disc electrode method. We show that a simultaneous carbonization and activation process in the presence of NaOH is the most effective towards creating the best catalyst precursor for the ORR, as the lignin-derived nanocarbon shows higher electrochemical activity towards the ORR than commercial N-doped graphene (Fig 1).

References

[1] J. Deng, M. Li, Y. Wang, Green Chem. 18 (2016) 4824–4854.

[2] D.S. Bajwa, G. Pourhashem, A.H. Ullah, S.G. Bajwa, Ind. Crops Prod. 139 (2019) 111526.

Figure 1
ORR Activity and Surface Strain Relations of Commercial Pt Alloy Catalysts
Authors: Brandes Benedikt Axel , Kelly Daniel , Liu Pei , Hansen Thomas Willum , Jensen Jens Oluf Oluf , Li Qingfeng , Cleemann Lars
Published: July 2022

Understanding and improving the catalysts for the ORR (Oxygen Reduction Reaction) is of great importance for the development of low temperature fuel cells. Within the past two decades great effort has been taken into the development of platinum alloy nano-catalysts and brought to commercialization. While thorough studies on the activity and stability of the individual catalysts have received great attention in the scientific literature, consistent comparisons of different platinum alloy nano-catalysts are scare: Due to different preparation methods and experimental conditions, the reported specific activities of, e.g. Pt3Co/C, vary by one order of magnitude [1][2]. In the first part of this talk we will present consistent electrochemical measurements on 7 different commercially available platinum alloy nano-catalysts (20% Pt loading on Vulcan XC-72R). In the second part we will present our results in context of the scientific understanding the ORR on platinum-based catalysts. Therefore, we conducted an extensive TEM survey on the measured nano-catalysts and gained further insights into the platinum surface strain. We find that the platinum surface strain of nano-catalysts is not only a phenomenon of an over-layer formation on platinum alloys, but also an inherent property of its nano-particular form.

Wang, C. et al. “Monodisperse Pt3Co nanoparticles as a catalyst for the oxygen reduction reaction: Size-dependent activity.” Journal of Physical Chemistry C, 113(45), 19365–19368. https://doi.org/10.1021/jp908203p

Koh, S. et al. “Activity-stability relationships of ordered and disordered alloy phases of Pt3Co electrocatalysts for the oxygen reduction reaction (ORR).” Electrochimica Acta, 52(8 SPEC. ISS.), 2765–2774. https://doi.org/10.1016/j.electacta.2006.08.039

Figure 1
(Digital Presentation) Activated Carbon Supported Ni-Co Layered Double Hydroxides Nanowires: An Effective and Low-Cost Electrocatalyst Towards Ethanol Oxidation Reaction in Alkaline Media
Authors: Baruah Sarmistha , Alape Seetharam Akshai kumar , Peela Nageswara Rao
Published: July 2022

Developing nanostructured architectures using non-noble, low-cost transition metals with good electrocatalytic activity and durability to replace noble electrocatalysts such as Pt and Pd have gained considerable attention in the field of sustainable and clean energy production technology. To address this, we adopted a facile synthesis route to synthesize Ni-Co layered double hydroxides (NiCo-LDH) nanowires supported on Activated Carbon (AC) via a one-pot hydrothermal synthesis method. The resulting NiCo-LDH nanowires, possessing a crystallite size of ~16.15 nm and a Surface area of 100.81 m2/g, have been utilized as a bifunctional electrocatalyst for ethanol oxidation reaction (EOR) in an alkaline medium. The electrochemical performance of the synthesized catalyst was investigated by Cyclic Voltammetry (CV), Chronoamperometry (CA), and Electrochemical Impedance Spectroscopy (EIS) techniques at room temperature. Impressively, NiCo-LDH/AC exhibited good electrocatalytic activity of 9.79 mA.cm-2 at 1.51 V vs. Saturated Calomel Electrode (SCE) and retained remarkable stability even after 200 cycles in 0.1 M NaOH with 1 M EtOH. The better electrocatalytic activity of NiCo/AC catalyst can be attributed to the presence of active sites and porous structures as well as the good electron transfer conductivity of AC. The attractive performance and facile synthesis of NiCo-LDH supported on AC highlights its potential application as an anodic material in direct ethanol fuel cells (DEFCs).
(Invited) Kinetics of Dye-Sensitized Water Oxidation Catalysis in Natural Sunlight
Authors: Houle Frances , Massad Ramzi , Cheshire Thomas P , Fan Chenqi
Published: July 2022

The couplings of ultrafast electronic excitation, charge injection and charge transfer processes to the catalytic cycles involved in water oxidation using molecular dye-catalyst photoelectrosynthesis systems are examined using detailed stochastic chemical kinetics simulations. By modeling the full timescale from subpicoseconds to many minutes and assuming illumination by the sun (AM 1.5), we have gained insights to how 4-photon catalytic cycle works when stimulated by relatively rare interactions with light. In this talk the model will be described, and its predictions for how catalyst and dye state populations evolve over time and how the flow of the catalytic cycle works will be discussed.
(Invited, Digital Presentation) Design, Preparation and Characterization of Photofunctional Materials Based on Energy-Resolved Distribution of Electron Traps
Authors: Ohtani Bunsho
Published: July 2022

How can we design functional solid materials, such as catalysts and photocatalysts? What is the decisive structural parameters controlling their activities, performance or properties? What is obtained as structural properties by popular conventional analytical methods, such as X-ray diffraction (XRD) or nitrogen-adsorption measurement, is limited to bulk crystalline structure and specific surface area, i.e., no structural characterization on amorphous phases, if present, and surface structure has been made so far. This is because there have been no macroscopic analytical methods to give surface structural information including possibly-present amorphous phases. Recently, we have developed reversed double-beam photoacoustic spectroscopy (RDB-PAS) which enables measure energy-resolved distribution of electron traps (ERDT) for semiconducting materials such as metal oxides [1,2]. Those detected electron traps (ETs) seem to be predominantly located on the surface for almost all the metal oxide particles, and therefore they reflect macroscopic surface structure, including amorphous phases, in ERDT patterns. Using an ERDT pattern with the data of CB bottom position (CBB), i.e., an ERDT/CBB pattern, it has been shown that metal oxide powders, and the other semiconducting materials such as carbon nitride, can be identified without using the other analytical data such as XRD patterns or specific surface area, and similarity/differentness of a pair of metal-oxide samples can be quantitatively evaluated as degree of coincidence of ERDT/CBB patterns. In this talk, an approach of material design based on the ERDT/CBB-pattern analyses is introduced [3].

[1] Nitta, A.; Takase, M.; Takashima, M.; Murakami, N.; Ohtani, B. A Fingerprint of Metal-oxide Powders: Energy-resolved Distribution of Electron Traps. Chem. Commun.
2016, 52, 12096-12099. [2] Nitta, A.; Takashima, M.; Murakami, N.; Takase, M.; Ohtani, B. Reversed double-beam photoacoustic spectroscopy of metal-oxide powders for estimation of their energy-resolved distribution of electron traps and electronic-band structure. Electrochim. Acta
2018, 264, 83-90. [3] Nitta, A.; Takashima, M.; Takase, M.; Ohtani, B. Identification and characterization of titania photocatalyst powders using their energy-resolved distribution of electron traps as a fingerprint. Catal. Today
2019, 321-322, 2-8.
Photoanode Interface and Surface Treatment Effect in Dye-Sensitized Photo Electrochemical Systems on Oxidative Cleavage of Lignin
Authors: Kang Hyeong Cheol , Kim Saerona , Yoo Kicheon , Leem Gyu , Lee Jae-Joon
Published: July 2022

Traditionally, Dye-sensitized photo electrochemical cells (DSPECs) have been targeted for solar-driven water splitting as production of fuels in aqueous media. Recently, hydrogen atom transfer incorporated dye-sensitized photo electrochemical cell (HAT-DSPEC) which used photocatalyst and homogeneous catalysts incorporating system was suggested for the decomposition process of lignin. This HAT-DSPEC system representing conversion efficiencies over 90% resulted in the formation of the oxidized ketone product from model compounds under simulated solar illumination with an applied bias 0.4 V vs Ag/Ag+
for 24 hrs. However, they have several issues such as long reaction time, low stability and high bias potential.

To overcome these problems, in this study, dye-sensitized photovoltaics’ advanced technic is applied. In HAT-DSPEC system, photo-anode (TiO2@Dye) has important role to produce oxoammonium species by oxidizing HAT mediator. And these oxidized HAT do a catalytic reaction with target materials: lignin model compounds (LMCs). However, in photo-anode, lots of charge recombination and electron back transfer occurs on the FTO and TiO2 surface. So, for effectively producing oxoammonium species from photoelectrode, using blocking layer to passivate FTO surface from electrolytes and applying TiCl4 post-treatment enhances charge transport in TiO2. The photocurrent response of the m-TiO2@Ru470 photoelectrode in a nonaqueous electrolyte was examined with increasing mediators concentration during light on/off cycles under AM 1.5G illumination (100 mW/cm−2), with an applied bias 0.4 V vs Ag/Ag+. Comparing three kinds of condition such as m-TiO2, BL/m-TiO2, BL/m-TiO2/TiCl4 post treatment, showed a significant increase in maximum photocurrent up to approximately 49.3, 101.3, 231.6 μA/cm−2 with 5 mM NHPI/2,6-Lutidine mediator. This result indicates that the blocking layer and TiCl4 post treatment enhanced electron life time and collection efficiency in the photoelectrode, as well as enhancing the capability of producing oxoammonium species.
Large Non-Classical Electrostriction in Aliovalent and Isovalent Doped Ceria
Authors: Varenik Maxim , Wachtel Ellen , Ehre David , Gaver Elad , Lubomirsky Igor
Published: July 2022

The majority of commonly used electrostrictive ceramics are based on lead manganese niobate. These ceramics display large electrostriction strain coefficients ≈ 10-16 m2/V2 at frequencies up to a few kHz. However, they suffer from major drawbacks: they require high driving currents (dielectric constant >10000), contain toxic elements, and are incompatible with thin film Si-microfabrication techniques.

We have recently reported that ceria ceramics doped with aliovalent cations having crystal radii smaller than that of cerium, display increased high frequency (f >100Hz) longitudinal electrostriction strain coefficients |M|. For instance, with 10 mol% Lu3+ or Yb3+ lanthanide dopants, |M| ~ 10-17 m2/V2 is observed for f >100Hz . Despite Yceria ~200GPa and eceria ~ , these electrostriction strain coefficients are 100-fold larger than estimated on the basis of Newnham’s scaling law for “classical” electrostrictors. Such “non-classical” behavior has been attributed to the formation of highly polarizable, elastic dipoles reorienting under external electric field.

Surprisingly, doping with small isovalent dopants, such as Zr and Hf , produces an increase in |M| to , independent of frequency up to several kHz, as determined by converse electrostriction measurements. The introduction of Zr raises the dielectric constant more than predicted by the Clausius-Mossotti relation. This suggests that the presence of a small dopant creates a highly polarizable unit which may be responsible for the large electrostriction strain coefficient. Our results demonstrate that, by systematically adjusting the composition of ceria-based solid solutions, the possibility exists for development of technologically useful electrostrictive materials which are, at the same time, ecologically sound and fully compatible with Si-microfabrication.
(Invited) Pressure-Tailored Lithium Deposition and Dissolution in Lithium Metal Batteries
Authors: Fang Chengcheng , Lu Bingyu , Pawar Gorakh M. , Zhang Minghao , Cheng Diyi , Chen Shuru , Ceja Miguel , Doux Jean-Marie , Cai Mei , Liaw Boryann (Bor Yann) , Meng Shirley
Published: July 2022

Unregulated lithium (Li) growth is the major cause of low Coulombic efficiency, short cycle life and safety hazards for rechargeable Li metal batteries. Strategies that aim to achieve large granular Li deposits have been extensively explored, and yet it remains a challenge to achieve the ideal Li deposits, which consist of large Li particles that are seamlessly packed on the electrode and can be reversibly deposited and stripped. Here we report a dense Li deposition (99.49% electrode density) with an ideal columnar structure that is achieved by controlling the uniaxial stack pressure during battery operation. Using multiscale characterization and simulation, we elucidate the critical role of stack pressure on Li nucleation, growth and dissolution processes and propose a Li-reservoir-testing protocol to maintain the ideal Li morphology during extended cycling. The precise manipulation of Li deposition and dissolution is a critical step to enable fast charging and a low-temperature operation for Li metal batteries.
(Invited) Mesoscale Reaction Kinetics Modulated By Structural and Compositional Heterogeneity in Battery Cathode Materials
Authors: Liu Yijin
Published: July 2022

Doping, coating, and particle engineering for cathode materials are broadly adopted by both academia and industry to improve the battery performance. The lack of an in-depth understanding for the underlying mechanism, however, makes it a largely try-and-error process with unsatisfactory efficiency and effectiveness. This is particularly true for the electrochemical reaction kinetics that is heterogeneous over a broad range of length scales and is determined collectively by the cathode’s electronic structure, lattice configuration, and micro-morphology.

In this presentation, I will talk about the use of advanced synchrotron techniques for imaging the cathode particles with structural, chemical and compositional sensitivities. We will talk about the mutual modulation between the surface chemistry and the bulk charge distribution and mechanical cracking. As an example, we will discuss how a facet-dependent dopant segregation in Zr-modified single-crystal LiNi0.6Co0.2Mn0.2O2 cathode would modulate its mesoscale reaction kinetics. This study suggests that a delicately controlled dopant distribution is a viable strategy for designing the next-generation battery cathode with superior structural and chemical robustness.
(Invited) The Stability and Kinetics of the Li/Solid Electrolyte Interface
Authors: Sakamoto Jeff
Published: July 2022

Owing to the potential to achieve >1000 Wh/L and >400 Wh/kg while exhibiting a dramatic improvement in safety, Li-metal solid-state batteries (SSBs) are promising technology to accelerate the widespread adoption of EVs. However, their remain gaps in knowledge in understanding the mechanical and electrochemical phenomena that control the stability and kinetics of the Li/solid electrolyte (SE) interface.

It is well known that Li (and Na) can penetrate ceramic and polymer solid electrolytes during charging. The term critical current density (CCD) is frequently used to determine the maximum charging rate before Li filaments penetrate. When normalized to a flat planar interface, CCDs during plating in literature range between 0.1 and 10 mA/cm2. Indeed, there is a broad range CCDs upon charging, moreover the role of pore formation during stripping has shed light on the factors that contribute Li metal penetration. In addition, factors can affect CCD such as charge passed (0.01 to 3 mAh/cm2), temperature (25 to 200 oC), pressure (0 to tens of MPa), and Li thickness (0.1 to 750 microns).

In this presentation, the aspects that collectively contribute to determining the stability and kinetics of the Li/SE will be discussed. The discussion with shift the recent focus on Li penetration during charging to Li void formation at the interface during stripping in cells that use commercially relevant Li thickness (< 20 microns), “anode-free” or in-situ formed Li anodes, LLZO SE. The results of this work can help guide efforts develop Li metal SSB for use in EVs.

Professor Jeff Sakamoto has 20 years of experience studying and translating ceramic materials for electrochemical materials into energy technologies for terrestrial and space applications. He was a senior researcher at the Caltech Jet Propulsion Laboratory (2000-2007), a Professor at Michigan State University (2007-2014), and has been a Professor at the University of Michigan since 2014. The Sakamoto group synthesizes ceramic electrolytes, tests their electrochemical and mechanical properties, and develops manufacturing processes for solid state batteries. Dr. Sakamoto is a Kavli Frontiers of Science Fellow, and was a chair, organizer, speaker, and delegate at the National Academy of Sciences Frontiers of Science and the National Academy of Engineering Frontiers of Engineering Symposia. Dr. Sakamoto received two Major Space Act Awards from the NASA Inventions and Contributions Board, is the primary contributor on 34 patents and received the Teacher-Scholar (2013), and Withrow Excellence in Teaching (2009) Awards at Michigan State University.
(Invited, Digital Presentation) Understanding Interfacial Chemo-Mechanics of Two-Dimensional Materials-Based Heterogeneous Functional Materials for Energy Storage
Authors: Datta Dibakar
Published: July 2022

Two-dimensional (2D) materials and their heterostructures (2D + nD, n = 0,1,2,3) attracted enormous interest in wide range of applications including electrochemical systems, e.g., batteries. Electro-chemo-mechanics, the coupling of mechanics and electrochemistry, plays a crucial role in designing these systems. This talk considers battery as a model system and demonstrates the role of 2D materials in overcoming various interfacial electro-chemo-mechanical challenges. 2D materials are engineered as the van der Waals (vdW) “slippery” interface. For example, silicon (Si) electrodes can be placed over the graphene-coated current collector for Lithium-Ion Batteries (LIBs). This arrangement provides less stress build-up and less stress “cycling” on the vdW slippery substrate instead of a fixed interface. 2D materials such as MXenes can also be used to replace polymer binders, e.g., in Si-based LIBs. Our DFT studies show more stable performance and higher Coulombic efficiency for Si films deposited on graphene-coated nickel (i.e., slippery interface) than conventional nickel current collectors. The interface strength of monoclinic Se (selenium) is 0.43 J/m2, which is similar in magnitude in amorphous Si with graphene (0.41 J/m2). However, the interface strength of c-Se on a 3D aluminum (Al) current collector is higher (0.99 J/m2), suggesting a stronger adhesion for 3D/3D interface than 3D/2D interface. Furthermore, interface strength variation between a-Si and Ti3C2Tx MXenes are determined for various surface functional groups (Tx). The completely hydroxylated Ti3C2 has the highest interface strength of 0.60 J/m2 with a-Si. The talk also summarizes our recent efforts in developing High Dimensional Deep Learning Potential (HDDLP) to study interfacial electro-chemo-mechanics in 2D materials-based systems. Our computational results are in good agreement with experiments. Besides batteries, our comprehensive interface analyses are beneficial in advancing understanding of other 2D materials-based systems, e.g., sensors, fuel cells, solar cells, nanomedicine, soft-actuators, etc.
(Invited) Developing Barrier Layer Free Oxygen Electrode for Solid Oxide Cells
Authors: Zhang Yongliang , Tang Qiming , Huang Kevin
Published: July 2022

High temperature solid oxide cell (SOC) technology is attracting considerable interest in recent decades for clean power generation and hydrogen production (green hydrogen) when combined with low-cost renewable energy. The key driver for such a strong interest is its superior thermodynamic efficiency and high-rate power and hydrogen production. However, the current scale-up and commercialization efforts are hindered by the insufficient durability and high cost, both of which are resulted from the high operating temperature (700-800oC). A further reduction in operation temperature to, e.g. below 700oC, is the best solution to address the durability and cost issues. As the operating temperature is reduced, the resistances of cell components increase correspondingly. To decrease the resistances, one can thin out or use high-conductivity electrolyte membranes, open up microstructure of fuel (or hydrogen) electrodes substrate and employ oxygen electrocatalytically active oxygen electrodes. Unfortunately, a direct use of active oxygen electrodes in SOCs has been proven formidable due to their reaction with electrolytes (ZrO2-based) and very high thermal expansion coefficient. To address the first problem, applying a CeO2-based barrier layer between electrolytes and oxygen electrodes is currently the solution. However, introduction of such a barrier layer considerably increases the ohmic resistance (sometimes as high as 2-3x), thus defeating the purpose of boosting cell performance. To address the second problem, mixing the active oxygen electrode with CeO2-based material or infiltrating it into a thermally compatible skeleton is currently the solution, but CeO2-based barrier layer is still needed.

Therefore, a key development for reduced-temperature ZrO2-based SOCs is to find an active oxygen electrode without the need of a barrier layer. Here we show that a composite consisting of La0.8Sr0.2MnO3 (LSM), an excellent electronic conductor, and (Bi0.75Y0.25)0.93Ce0.07O1.5±δ (BYC), an excellent ionic conductor, is a potential barrier layer free oxygen electrode for reduced-temperature SOCs. We also show fabrication of open structured hydrogen electrode substrate to facilitate H2/H2O diffusion and increase the performance of HE.
(Invited) Membrane Coated Electrocatalysts for Selective and Stable Oxygen Evolution in Seawater
Authors: Baxter Amanda F. , Fraga Alvarez Daniela V. , Kuvar Dhruti , Esposito Daniel V.
Published: July 2022

Seawater electrolysis has the potential to be a more sustainable means of hydrogen production compared to conventional water electrolysis which relies on highly pure water. This is particularly true for arid coastal regions with access to seawater and ideal conditions for harvesting solar and wind energy, but where fresh water is already scarce.[1] Seawater electrolysis is challenging due to the large concentration of chloride ions, which can be detrimental to electrocatalyst stability. Furthermore, the presence of chloride ions allows the chlorine evolution reaction (CER) to compete with the oxygen evolution reaction (OER) at the anode. Although Cl2 is of industrial value, global hydrogen production already exceeds chlorine production, and demand for hydrogen is projected to grow more rapidly. Additionally, since Cl2 is toxic and harmful to the environment, implementing seawater electrolysis is simplified if pure oxygen is produced and can be safely vented to the atmosphere.

Our group has shown that ultrathin semi permeable oxide overlayers can be designed to selectively transport reactants to the active catalyst at the buried interface.[2-3] Importantly for seawater electrolysis, the oxide overlayer selectively rejected chloride ions while allowing for water transport.[4] Thus, the oxide overlayer acts as a membrane, and the composite material can be referred to as a membrane coated electrocatalyst (MCEC). An additional advantage of the MCEC architecture compared to conventional electrocatalysts is enhanced stability.[5] This makes MCECs particularly attractive for stable and selective OER in seawater. This work describes how MCECs can (i) improve catalyst stability and (ii) enable selectivity for OER over CER by impeding transport of chloride ions to the catalyst at the buried interface. This work explores the fundamental relationships between chloride ion transport through different oxide overlayer materials. This knowledge is then applied to prepare MCECs supported on high surface area porous electrodes.

References

[1] S. Dresp, et al., ACS Energy Lett., 4, 933 (2019).

[2] N. Y. Labrador, et al.
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[3] M. E. S. Beatty, et al., ACS Appl. Energy Mater.,
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[4] A. A. Bhardwaj, et al.
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[5] N. Y. Labrador, et al
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Investigating Surface Sensitivity of Ni-Rich Cathode Material Towards CO2 and H2O
Authors: Chen Heyin , Ericson Tove , Kokkonen Esko , Temperton Robert , Andersson Margit , Mikheenkova Anastasiia , Brant William , Hahlin Maria
Published: July 2022

Layered Ni-rich transition metal oxide materials have been considered as the most promising cathode utilized in Li-ion batteries, e.g., LiNi0.8 Mn0.1 Co0.1 O2 (NMC 811). However, one of the drawbacks of NMC 811 is its high air sensitivity, leading to a degradation layer forming on the surface, and a lower cycling performance. Since the degradation mechanism is not fully understood, in this work, we use ambient pressure photoelectron spectroscopy (APPES)1 to investigate the surface sensitivity of NMC 811 towards CO2 and H2O in situ, aiming to determine the factor triggering the degradation. Before gas exposure, NMC 811 surface was Ar+ sputtered to remove the pre-existing boron oxide coating. The changes in surface chemical composition were monitored as a function of time and gas pressure. Results show that carbonate compounds are formed on the surface when NMC 811 is exposed to CO2. The carbonate compounds start to appear already within 2 minutes in CO2 at around 10-5 mbar. More interestingly, this reaction is reversed at around 3x10-6 mbar. Changes induced by water are slower, however, the water vapour effect on NMC 811 surface is irreversible. Results indicate that lithium hydroxide is formed, where Li+/H+ exchange on the surface is a possible route.2

Kokkonen, E.; Lopes Da Silva, F.; Mikkelã, M.-H.; Johansson, N.; Huang, S.-W.; Lee, J.-M.; Andersson, M.; Bartalesi, A.; Reinecke, B. N.; Handrup, K.; Tarawneh, H.; Sankari, R.; Knudsen, J.; Schnadt, J.; Såthe, C.; Urpelainen, S., Upgrade of the SPECIES beamline at the MAX IV Laboratory. Journal of Synchrotron Radiation
2021,
28 (2), 588-601.

Hartmann, L.; Pritzl, D.; Beyer, H.; Gasteiger, H. A., Evidence for Li+/H+ Exchange during Ambient Storage of Ni-Rich Cathode Active Materials. Journal of The Electrochemical Society
2021,
168 (7), 070507.

Figure 1