bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrochemical Synthesis of Ammonia from Nitrogen and Nitric Oxide at Room Temperature over Nanostructured Transition Metal Catalysts
Authors: Shanmugam Sangaraju , Markandaraj Sridhar Sethuram
Published: November 2022

Transition metals have been recognized as excellent and efficient catalysts for transforming gaseous molecules into value-added chemicals. Electrochemical ammonia synthesis through the atmospheric reduction of nitrogen and nitrogen oxide is a promising method for sustainable fertilizer and carbon-free hydrogen energy carriers. However, it is a great challenge to main the activity and stability of the catalyst due to its corrosive nature and vigorous reaction conditions involved in the electrochemical transformations.

We report stable core-shell electrocatalysts that utilize transition metal nanoparticles in the core and nitrogen-doped porous carbon architecture in the shell for the efficient electroreduction of N2 and NO to ammonia (NH3). The carbon shell prevents the dissolution of Ni nanoparticles. It ensures the long-term stability of the catalyst, whereas the Ni nanoparticles involve in the catalytic reduction of NO to NH3 during electrolysis. The catalyst images reveal a core-shell structure composed of dark metallic spherical particles at the core and layered carbon as a shell surrounding the nanoparticles (Fig. 1a). A broad particle size distribution of 15 nm to 50 nm was observed, and the core-shell particles were interconnected by a smooth carbon matrix. The heteroatom content and the shell thickness strongly influence the catalytic activity. A high faradaic efficiency (FE) of 72.3% at 0.16 VRHE is achieved (Fig. 1b). Moreover, the full-cell electrolyzer was constructed by coupling developed cathodes and commercial RuO2 as anode for oxygen evolution reaction, which delivered a stable performance over several cycles at 1.5 V. Further, we demonstrate the solar to fuel transformation by integrating with a PV-electrolyzer cell, it presented an appreciable FE of >50%.

Fig. 1. (a) TEM image of core-shell catalyst, (b) comparison of FE and NH3 yields on various electrocatalysts for the nitric oxide reduction reaction.

Figure 1
Electrocatalytic Conversion of Methane to Ethylene Utilizing Highly Durable Barium Niobate Perovskites
Authors: Denoyer Luke H , Benavidez Angelica , Garzon Fernando H. , Ramaiyan Kannan
Published: November 2022

Pursuing efficient conversion of methane to value-added products such as olefins and aromatics is a prospective use of natural methane feedstocks. The demand for on-site methane conversion has further increased due to the recent discoveries of shale gas reserves. Electrochemical methane conversion provides a means to control the surface oxide ion concentration, aiming to eliminate the over-oxidation of methane while also aiding in methane activation via applied potential. High temperature electrolysis processes provide improved reaction kinetics. Unfortunately, high temperature operation also leads to material degradation via sintering, crystal structure disproportion to thermodynamically more stable phases, and interfacial reactions that reduce performance. We demonstrated that the Sr2Fe1.5Mo0.5O6-
d (SFMO) perovskite which was reported with desirable methane activation properties had poor chemical and electrochemical stability as it formed carbonates and coke under methane rich environments.[1][2] Here we present an exciting class of barium niobate perovskite materials with varying levels of Mg and Fe co-doping that show promising catalytic activity towards methane activation in the electrochemical and conventional heterogeneous oxidative coupling environment. The perovskite material was prepared by conventional solid-state methods and by microwave synthesis methods to compare the role of surface area. Thermogravimetric analysis and temperature programmed reaction measurements under methane show superior chemical stability in comparison to SFMO perovskites. These catalysts’ electrochemical properties are evaluated by cyclic voltammetry, impedance spectroscopy, and chronoamperometric measurements coupled with mass spectra analysis that demonstrate durable operation for five continuous days. A maximum ethylene production of 277 mmolcm-2h-1 with a faradaic efficiency of 20% at 1V was obtained. Stability determinations of our perovskite oxide electrocatalysts for EC-OCM offer an excellent example of our approach towards evaluation of materials durability under the highly carburizing environments. These perovskite materials could also serve as a support for a wide variety of catalyst materials for high temperature applications thus opening new possibilities.

References

[1] K. P. Ramaiyan, L. H. Denoyer, A. Benavidez, and F. H. Garzon, “Selective electrochemical oxidative coupling of methane mediated by Sr2Fe1.5Mo0.5O6-δ and its chemical stability,” Commun. Chem., vol. 4, no. 1, p. 139, 2021, doi: 10.1038/s42004-021-00568-1.

[2] C. Zhu, S. Hou, X. Hu, J. Lu, F. Chen, and K. Xie, “Electrochemical conversion of methane to ethylene in a solid oxide electrolyzer,” Nat. Commun., vol. 10, no. 1, p. 1173, 2019, doi: 10.1038/s41467-019-09083-3.

Figure 1
Ethylene Production from Oxidative Coupling of Methane in Solid Oxide Electrochemical Cells
Authors: Priest Cameron , Meng Yuqing , Wang Lucun , Ding Dong
Published: November 2022

The oxidative coupling of methane (OCM) to ethylene is a potentially more economical and environmentally benign approach for ethylene production compared to conventional high temperature thermal cracking of natural gas. The OCM reaction is typically conducted in packed bed flow reactors under thermal conditions in the presence of a heterogeneous catalyst. However, due to the intrinsic thermodynamic and kinetic constraints, the existing catalytic systems operated in packed bed reactors have not yet met the techno-economic requirements for the commercialization of this process. As an alternative, membrane reactors that selectively conduct the oxygen ions (O2-) could potentially offer significantly higher methane conversion and C2 product selectivity compared to conventional packed bed reactors. The lower partial pressure of oxygen and the distinct nature of oxygen species available for methane oxidation in the membrane reactor could effectively suppress the kinetics of the chemical transformations leading to the combustion products. In this context, solid oxide electrochemical cells (SOEC), specifically based on oxygen ion conducting membranes, are excellent platforms for conducting the OCM reaction. Here we demonstrate the development of novel SOECs integrated with a series of advanced OCM catalysts to achieve highly efficient ethylene production.
Achieving High-Efficiency CO2 Electro-Conversion in a Solid Oxide Cell
Authors: Sun Yanhua , Adjah-Tetteh Christabel , Wang Yudong , Jia Zhiyong , Yu Xingwen , Zhou Xiao-Dong
Published: November 2022

Carbon dioxide (CO2) emissions have been steadily increasing since the beginning of human civilization. The greenhouse effect and climate change aroused by the cumulative CO2 are severely impacting the global sustainable development and pose serious concerns for our future life. Strategies toward reducing the CO2 level encompass a series of processes of carbon capture, storage, utilization, and conversion; among them the conversion of CO2 to fuels and valuable chemicals is appealing toward the development of new sustainable technologies. As the highest oxidized form of carbon, CO2 is thermodynamically stable. The breaking of its strong C=O double bonds is an endergonic process, which requires highly active and expensive catalysts for activation at ambient temperatures. Therefore, conversion of CO2 with high-temperature electrolysis technologies represents a promising strategy, which is garnering increasing attention. In this study, we present a solid oxide electrolysis cell (SOECs) design for high-efficiency CO2 conversion. The fuel electrode in an SOEC is a critical component where CO2 reduction occurs. Therefore, we focus on the design and optimization of the fuel electrode from the perspectives of chemistry (composition) and architecture (especially the thickness) to enhance the efficiency of CO2 electrolysis. A Ni-based cermet layer was developed as an ideal CO2/CO fuel electrode, based on which the cell architecture was strategically optimized with prototype Ni-YSZ/YSZ/GDC/LSCF cells (YSZ: yttria-stabilized zirconia; GDC: gadolinium-doped ceria; LSCF: lanthanum strontium cobalt ferrite). Over the course of optimization, the Ni-YSZ cermet fuel electrode was methodologically fabricated with various thickness and the cells were operated at contracting temperatures. Meanwhile, the fuel was managed with different ratios of CO2 to CO and the O2 was supplied with different flow rates at the opposite electrode. At an exemplarily optimized condition, a high electrolysis current of 1.33 A cm-2 was achieved at 750 oC with a fuel comprising of 99% CO2 and 1% CO. To assist the cell optimization, electrochemical impedance spectroscopy (EIS) was particularly used to investigate the electrochemical properties of SOECs. Meanwhile, cell components were analyzed with scanning electron microscope (SEM) before and after the electrolysis operation to study the degradation behavior of SOECs that were operated under high-current electrolysis. The detailed cell design and experimental results will be comprehensively demonstrated and presented.
Development of Highly-Efficient CO2 Electrolysis Cell Stacks
Authors: Kiyota Yasuhiro , Kofuji Yusuke , Ono Akihiko , Mikoshiba Satoshi , Kitagawa Ryota
Published: November 2022

Low-temperature CO2 electrolysis technology, which converts CO2 into valuable products, has attracted attention for its potential to mitigate climate change caused by global warming. Various products, such as CO and ethylene glycol, can be obtained from electrochemical reactions [1,2]. CO, a useful raw material for hydrocarbons, is a particularly simple product. In order to implement an industrial-scale low-temperature CO2 electrolysis system, we must further reinforce the properties of the CO2 electrolysis cell: namely, energetic (energy conversion) efficiency, CO2 conversion rate (current density and scaling) and durability. For realizing high energetic efficiency, decreasing ohmic resistance and overvoltage is required. Therefore, a zero-gap electrolysis cell, which has short electrodes distance leading to lower ohmic resistance, has been adopted. The zero-gap configuration contains a membrane electrode assembly (MEA) constructed from cathode and anode electrodes and a diaphragm. Anion exchange membranes (AEMs) have been mainly used in past research as the diaphragm, however, the AEMs have several shortcomings for practical use as the diaphragm, e.g., low thermal stability, weak mechanical strength and high cost.

In this work, we have focused on porous membranes as a novel diaphragm which is more suitable for overcoming those instabilities and costs. We have achieved an increase in energetic efficiency of the zero-gap CO2 electrolysis cell using the porous membrane when compared to that of AEMs. We have experimentally revealed higher ion permeability, lower ohmic resistance and lower overvoltage when using the porous membrane, resulting in improvement of the energetic efficiency. Regarding CO2 conversion rate and durability, we have developed a large-scale cell stack constructed with ten layers of a 100 cm2 size cell and demonstrated durable operation over one month.

This work is partially supported by the Ministry of the Environment, Government of Japan.

[1] Y. Kofuji, A. Ono, Y. Sugano, A. Motoshige, Y. Kudo, M. Yamagiwa, J. Tamura, S. Mikoshiba and R. Kitagawa, Chem. Lett.
50, 482 (2021).

[2] J. Tamura, A. Ono, Y. Sugano, C. Huang, N. Hideyuki, and S. Mikoshiba, Phys. Chem. Chem. Phys.
17, 26072 (2015).
Anode Catalysts for Solid Oxide Fuel Cells That Run Directly on Hydrocarbon Fuels
Authors: Zhang Weilin , Zhou Yucun , Luo Zheyu , Nam Gyutae , Liu Meilin
Published: November 2022

Solid oxide fuel cells (SOFCs) can efficiently generate electricity from a wide variety of fuels, offering unique advantages over the conventional power generation systems based on combustion. In particular, SOFCs can directly use low-cost and readily available hydrocarbon fuels as the energy source. To be commercially competitive, however, breakthroughs in materials development is required. For instance, a durable and electro-catalytically active anode material or catalyst is needed that can facilitate hydrocarbon reforming and avoiding carbon deposition (coking) for SOFCs to operate stably on hydrocarbon fuels, including natural gas, ethanol, and iso-octane.

Hydrocarbon fuels, especially liquid ones, have several advantages over hydrogen fuel: low-cost, high volumetric energy density, and ease for transportation and storage. Currently, direct-hydrocarbon SOFCs suffer from severe performance degradation due to carbon deposition. In this presentation, we report a promising anode catalyst for SOFCs operated on various hydrocarbon fuels, from methane to ethanol and iso-octane. The catalyst has been successfully applied to both small button cells and tubular cells with an effective area of about 38 cm2. For both cases, our cells demonstrate stable performance for continuous operation of >1,000 hours.
Co-Generation of Hydrogen and Propylene Via Proton Conducting Fuel Cell Under Intermediate Temperature
Authors: Meng Yuqing , Wang Lucun , Ding Dong
Published: November 2022

Propylene and hydrogen are the two primary products of the proposed process. Propylene is an important raw material for polymer synthesis and chemical manufacture, while hydrogen is widely used in refining petroleum, treating metals, producing fertilizer, and processing foods. At present, the dominant technology for producing propylene is steam cracking, which is highly energy intensive and low energy efficiency due to side reactions and severe coke formation. This work demonstrates an electrochemical process which is achieved through a deprotonation reaction at the catalyst-assisted anode of an electrochemical membrane reactor (EMR) to co-produce propylene and hydrogen, using a highly active 3D ultra-porous nickel-free deficient layered perovskite anode, BaZrCe (BZC) electrolyte and Ni-cermet cathode. The electrochemical propane dehydrogenation reaction (PDR) performance was evaluated and optimized by varying reaction parameters, including current density, voltage, propane concentration, and temperature. Preliminary thermal catalytic measurements in a fixed bed flow reactor using a dilute (10%) propane gas as the feedstock. The results showed that propane conversion could reach up to 40% at 550°C. By reducing operation temperature to 350-500°C, the technology also improves the durability of the catalyst and the electrochemical system. Therefore, the proposed technology represents an innovative and significant improvement with respect to existing commercial processes.
Manufacturing of 5x5 cm2 Protonic Ceramic Electrochemical Cells at Idaho National Laboratory
Authors: Zhao Zeyu , Feng Wuxiang , Tang Wei , Wu Wei , Gomez Joshua , Ding Dong
Published: November 2022

Protonic ceramic electrochemical cells (PCECs) hold the promise for hydrogen production as well as flexible chemical manufacturing by in-situ hydrogen/proton use at intermediate temperatures (400-600oC). As the technology is emerging and fast growing, the production and manufacturing of 5x5 cm2
PCECs represent a key step to link the fundamental study on the academic-based button cells (e.g., 10 mm to 1 inch) to the higher technology readiness level (TRL) development with the industry standard unit (> 10x10 cm2) for the stack assembly. At Idaho National Laboratory, we developed the advanced manufacturing technologies and applied our knowledge and experience in materials science and engineering for such a transition. Significant advancement is achieved by integrating the materials, structure and interface engineering R&D into cell fabrication and manufacturing with the guidance of the quality assurance and quality control (QA&QC) system .to achieve reliable, repeatable, and durable performance for PCECs.
(Digital Presentation) Synthesis and Promoting Activity of Gd2O3 for Methanol Electro-Oxidation on Pt/C
Authors: Sharma Shuchi , Gangavarapu Ranga Rao
Published: November 2022

One of the challenges in electrocatalysis is to design either an efficient non-noble electrocatalyst or improve the electrocatalytic activity of Pt/C by incorporating promoters such as metal oxides, carbides and nitrides. Rare earth metal oxides such as CeO2 have been explored to promote methanol electro-oxidation on Pt/C electrocatalyst. It has been noted that the synthesis method has profound effect on the physiochemical and in turn electrochemical properties of metal oxide promoted Pt/C electrocatalysts. This concept is tested on Gd2O3 promoted Pt/C. Gd2O3 is prepared by precipitation (GdO-PC) method and polymer assisted method (GdO-PL). The oxygen storage capacity (OSC) of this oxide is correlated with the electrochemical activity of Gd2O3-Pt/C. GdO-PC has higher OSC and can release surface oxygen much easier as compared to GdO-PL for methanol electro-oxidation on Pt. The Gd2O3-Pt/C catalysts are prepared with Gd2O3, Vulcan carbon and Pt-salt (equivalent to 20 wt% Pt) using microwave assisted polyol reflux method. The electrocatalytic activity of Gd2O3-Pt/C towards methanol oxidation has been carried out by cyclic voltammetry, CO stripping experiments, chronopotentiometry, and chronoamperometry methods in acidic media. The measurements show that Pt-GdO-PC/C performs better than Pt-(GdO-PL)/C) and commercial Pt/C. This indicates that the synthesis route of Gd2O3 particles is crucial for promoting methanol electro-oxidation. The first principle calculations show that there is a charge transfer from Gd2O3 to Pt. (GdO-PC). It is concluded that higher OSC and charge transfer from Gd2O3 to Pt work in tandem to weaken the Pt-CO bond and oxidise CO to CO2, thus reducing the CO poisoning and enhancing the activity of the oxide promoted electrocatalyst.

Figure 1
Advanced Electrochemical Impedance Analysis Using Distribution of Relaxation Times for in Operando Mechanistic Insights of Fuel Cell and Water Electrolyzer Designs
Authors: Giesbrecht Patrick K , Freund Michael S
Published: November 2022

The development of sustainable and carbon-neutral alternative energy frameworks and chemical feedstocks requires rapid production of scalable water electrolyzer designs for hydrogen production.[1] Coupling electrolyzers to renewable energy supplies can provide a ‘green’ hydrogen production pathway, enabling clean production of chemical feedstocks as well as an energy storage framework. Current acid-based electrolyzer designs, however, integrate precious metals for stable operation, where drastic reductions in iridium use and increased cell durability are required for scalable deployment.[2] This requires the ability to monitor changes to the cell in operando for rapid diagnostics during initial and long-term operation under sustained or intermittent profiles. One technique proposed is electrochemical impedance spectroscopy (EIS), which can provide a breakdown of the cell resistances based on the timescale of the process.[3] Further analysis by circuit modeling, however, requires significant insight into the system for accurate interpretations. By coupling conventional EIS methods with distribution of relaxation times (DRT) analysis, the number of processes impacting cell operation can be determined without a priori knowledge of the system.[4] This has improved circuit modeling analysis of Li-ion batteries and solid oxide fuel cells.[5] Here, we demonstrate the power of EIS-coupled DRT analysis by analyzing the operation porous cathode and anode films of Nafion-based electrolyzer cells in half-cell and full cell configuration. Analysis of the electrodes in half-cell configurations provides estimates of kinetic parameters, active area, ionic conductivity, and diffusion coefficients associated with the electrode from a single EIS spectrum that are comparable to values obtained from in situ values.[6] Further analysis of the full cell operation with variable cathode gas composition provides insight as to the effect of the cathode gas composition on both the cathode and anode operation and stability. The work presented here will show the versatility and limitations of DRT-coupled EIS analysis of novel fuel cell and electrolyzer designs as well as present key findings for improving electrolyzer performance and stability.

[1]Ayers, K. et al. Annu. Rev. Chem. Biomolec. Eng.
2019, 10, 219-239.

[2]Pham, C. et al Adv. Energy Mater.
2021, 11, 2101998.

[3]Liu, H. et al. J. Phys. Chem. Lett.
2022, 13, 6520-6531.

[4]Wan, T. et al. Electrochimica Acta
2015, 184, 483-499.

[5]Dierickx, S., Ivers-Tiffee, E. Electrochimica Acta
2020,
355, 136764.

[6]Giesbrecht, P.K., Freund, M.S. J. Phys. Chem. C
2022, 126, 132-150.
Modeling Mechanical Behavior of Membranes in Proton Exchange Membrane Water Electrolysis
Authors: Kink Julian , Ise Martin , Bensmann Boris , Hanke-Rauschenbach Richard
Published: November 2022

The reliability of a proton exchange membrane water electrolysis (PEMWE) depends significantly on the long-term mechanical stability of the membrane due to its relatively low mechanical robustness. Membrane defects can be caused, for example, by severe mechanical stress in the critical gap between the cell frame and the porous transport layer (PTL). In this work the mechanical stresses and strains are quantified for such scenarios by using a finite element (FE) analysis which is applied to a simplified model setup.

Nafion® is used as a standard material for the membrane and an appropriate material model is implemented into a FE software. The used parameters are based on and validated by experimental data from tensile tests to ensure matching with real PEMWE systems. The validated material model is used in the cell simulation to identify resulting stresses and strains during assembly and operation. In accordance with experimental experience, no critical states were identified. Furthermore, differential pressure up to 10 bar in the model could not cause any significant change compared to deformations resulting from boundary conditions for balanced pressure operation. Varying the gap size between the cell frame and PTL resulted in a buckling in the simulated membrane for sizes of 0.3 mm and more during membrane swelling.
Intrinsically Microporous Ion-Pair Coordinated Membranes for HT-Pemfcs
Authors: Lee Albert S , Gu Jinsuk , Jung Jiyoon , Park Young Sang , Lee Jung-Hyun
Published: November 2022

Fuel cells are electrochemical devices with high energy efficiency expected to be applied economically and eco-friendly across various energy sectors. Low-temperature polymer electrolyte membrane fuel cells (LT-PEMFCs) using Nafion operates at a relatively low operating temperature (60-80°C) and a full hydration condition. HT-PEMFC is operable at high temperatures (140-180°C), but requires anhydrous conditions to avoid loss of doped phosphoric acid (PA). In this study, polymer membranes designed through with intrinsic microporosity were synthesized through super acid polycondensation. We demonstrated that high proton conductivity (106.33 mS cm-1 at 180℃) is obtained by forming phosphoric acid filled ion-channels within the interconnected microporous structure. Moreover, ion-pair coordinated PIMs are fabricated by methylation of PIMs to improve PA retention even under humidified conditions. It is suggested that the water tolerance of ion-pair coordinated PIMs is improved and can be operated under various conditions regardless of humidification and operating temperature.
(Digital Presentation) Characterization Techniques to Evaluate the Ageing of Oer Based Reversal Tolerant PEFC Anodes during Start-up/Shut-Down Events
Authors: Bentele Dominik , Aylar Kerem , Olsen Katja , Klemm Elias , Eberhardt Sebastian H.
Published: November 2022

Anode durability is a major aspect to achieve the ambitious durability targets of low temperature polymer electrolyte fuel cells (PEFCs) for transportation and stationary applications. The introduction of oxygen evolution reaction (OER) co-catalysts has been widely established to attain reversal tolerant anode catalyst layers (ACLs).1, 2 By the introduction of OER co-catalysts, the tolerance to gross fuel starvation events can be substantially improved and the fuel cell is effectively protected from severe damage.2

OER degradation by transient anode conditions has been reported recently, originating for example from start-up/shut down (SUSD) events.3 For the present work, two SUSD accelerated stress tests (ASTs) variants were developed to provoke substantial OER co-catalyst degradation while minimizing common cathode degradation by the so-called reverse-current effect. Advanced characterization techniques were developed to investigate the OER and hydrogen oxidation reaction (HOR) catalyst degradation. The results reveal a structural change within the anode catalyst layer and a substantial loss in reversal tolerance after PEFCs have been exposed to SUSD events. Furthermore, characterization methods are presented to investigate the crossover of IrO2 based OER co-catalyst from the anode to the cathode catalyst layer, promoted by transient anode conditions during start-up/shut-down. For state-of-the-art characterization methods to investigate the electrochemical surface area (ECSA) of platinum-based catalysts, the observed Iridium crossover was found to significantly affect the ECSA results.

References

T. Joo, L. Hu, B. K. Hong, J.-G. Oh and S. Litster, Journal of Power Sources,
472, 228439 (2020).

T. R. Ralph, M. P. Hogarth, Platinum Metals Rev.,
46(3) (2002).

M. Fathi Tovini, A. M. Damjanovic, H. A. El-Sayed, J. Speder, C. Eickes, J.-P. Suchsland, A. Ghielmi and H. A. Gasteiger, J. Electrochem. Soc.,
168(6), 64521 (2021).

Figure 1
Hybrid Thermo-Electrochemical Energy Harvesters for Conversion of Low-Grade Thermal Energy into Electricity Via Tungsten Electrodes
Authors: Jung Sang-Mun , Kwon Jaesub , Lee Jinhyeon , Lee Byung-Jo , Kim Kyu-Su , Kim Yong-Tae
Published: November 2022

Thermo-electrochemical cells utilizing aqueous hexacyanoferrate electrolytes are recognized as an effective energy harvesting system for low-grade waste heat (≤170 °C) owing to their high stability and simple design. Nevertheless, the power generation of thermo-electrochemical cells is low due to the Seebeck coefficient of hexacyanoferrate electrolyte. Herein, we propose hybrid thermo-electrochemical cells using tungsten electrodes, exploiting the redox reaction of hexacyanoferrate and oxidation of the tungsten electrode. Enhanced Seebeck coefficient was attributed to the combination of the two reactions: the redox reaction of the electrolyte and oxidation reaction of tungsten electrodes. The developed tungsten electrode-based hybrid thermo-electrochemical cells generated a Seebeck coefficient of 1.66 mV K−1 and 425 mW m−2 at a dT of 50 °C, ~ 70% higher the power output of platinum and carbon electrodes. From an economic viewpoint, the cost of tungsten makes up for its inevitable consumption due to dissolution and the cost of periodic electrode replacement. Our system is an innovative solution, which might contribute to the commercialization of thermo-electrochemical cells.
(Digital Presentation) Reactive Magnetron Sputtering Deposition of La1.6Nd0.4NiO4 Coating As Cathode for Solid Oxide Fuel Cell
Authors: Ye Xiaolei , Luo Huan , Fourcade Sébastien , Mauvy Fabrice , Bertrand Pierre , Briois Pascal
Published: November 2022

Ln2NiO4 (Ln=La, Pr, Nd, etc.) materials with K2NiF4 structures are interesting materials for intermediate temperature solid oxide fuel cell (IT-SOFC) due to Mixed Ionic and Electronic Conductivity (MIEC) [1-2]. The present work is focused on the elaboration of La1.6Nd0.4NiO4 coating obtained by Reaction Magnetron Sputtering (RMS). This compound is a promising oxygen electrode able to decrease the operating temperature of SOFC. After a presentation of the deposition operating conditions for obtaining the films, the structural and microstructural characterizations of the coatings were, respectively, determined by XRD and SEM. The electrical properties were studied as a function of temperature by the 4-probe method. Electrochemical properties were investigated in a symmetrical cell electrode / YSZ / electrode by complex impedance spectroscopy. Finally, a complete cell composed of a commercial anode, and YSZ electrolyte made by RMS and the cathode of this study was tested under hydrogen and air in single SOFC cell configuration.

It appeared that the films are amorphous when processed and that they crystallize after an annealing treatment under air. According to this study, a correlation between crystalline structure, morphology and electrical properties will be presented and its last ones are completed by a thermogravimetry analysis.
(Digital Presentation) Fuel Cell Electrode Design - Using a Specially-Modified Force Tensiometer for Gas Bubble Adhesive Force Measurements on Nanostructured Copper Electrodes Submerged in a Liquid
Authors: Fidler Bob , Schaubach Sebastian
Published: November 2022

Direct liquid-feed fuel cells (DLFCs) have gained attention because of their low-cost, high power densities and clean energy. They have a bright future for both mobile and

stationary applications. DLFCs directly convert chemical energy into electrical energy by the oxidization of liquid fuels. Numerous nanostructured catalysts on the electrodes have been explored to improve the energy conversion efficiency. However, the behavior of the gas products (such as N2 and CO2) on the electrode surfaces received very little attention, which is critical to achieve better performance of the DLFCs especially at high reaction rates. The reason for this is that gas bubbles that accumulate on the surface will not only block the catalyst sites but also cause high pressure in the liquid flow area limiting the fuel crossover. It has been reported that the surface architecture can significantly affect the gas bubble adhesion behavior.

In this work, adhesive forces of the gas bubbles on planar and nanostructured films were measured. Using a force tensiometer outfitted with a video camera and software, adhesion force of the gas bubble on a flat Cu foil was measured. Adhesive forces and submerged liquid contact angle measurements of gas bubbles on planar and nanostructured Cu films are possible. Adhesive forces of liquids in air phase or of gas bubbles under liquid phase can also be analyzed. The special force tensiometer system with video upgrade combines a force measurement to determine the force of adhesion and an optical system to determine the area of contact between the liquid/gas and solid phase for each force that is measured. In such a way, force per area can be determined. The measurement procedure involves a liquid or gas bubble being pushed onto a solid substrate under air or liquid and then pulled off.
(Invited, Digital Presentation) Remembering George Blasse
Authors: Meijerink Andries
Published: November 2022

The impressive career of George Blasse in the field of luminescence started in 1964. Triggered by the discovery of YVO4:Eu3+ as red phosphor in cathode ray color TVs the management of Philips Research decided to re-establish the luminescence group and George Blasse was asked to lead the group. Very productive years followed in which George discovered many new phosphors, including YAG:Ce3+. In 1970 he made an unusual career switch and accepted the position of professor of Solid State Chemistry at Utrecht University. George Blasse led a highly successful research group for over 25 years and became internationally recognized for his research on luminescent materials. During his career he frequently attended ECS Meetings which has been and continues to be a place where reseaerchers from universities and industry in the field of luminescence materials meet and new phosphors and concepts are presented. I vividly remember attending the ECS meeting in Chicago in 1988 together with George.

George Blasse combined groundbreaking fundamental discoveries with societal relevance. He had a deep and also intuitive understanding of luminescence phenomena and often relied on clever chemical variations in host composition and structure to obtain insight in the underlying physics. Simple guidelines and clear design rules based on systematic and careful research of a wide variety of materials were discovered, explaining spectral variations and trends, for example in thermal quenching of luminescence for Eu3+. The constant energy difference between fd states of different lanthanides was pioneered by George Blasse and later became the basis for the now widely used Dorenbos model. Another area where the work of George Blasse was instrumental involved energy transfer and energy migration phenomena. He was able to translate the somewhat complex theoretical papers as those by Förster and Dexter into simple models and equations to understand and quantify energy transfer processes. George Blasse also made important contributions in understanding of the optical properties of s2 ions like Pb2+, Bi3+, Sb3+ and Sn2+. In recent years this work of George receives increasing attention in the light of extensive work on luminescence of these ions in double perovskites. In this presentation I will share memories and highlight the great contributions of George Blasse to our field.

Figure 1
(Invited) Combining the 5d→4f and 4f→4f Luminescence of Lanthanides for High-Quality Broad-Range Luminescence Thermometry
Authors: Zych Eugeniusz , Bolek Paulina , Sójka Małgorzata , Kulesza Dagmara , Zeler Justyna , Jedoń Joanna , Carlos Luis D. , Runowski Marcin , Trojan-Piegza Joanna , Shyichuk Andrii , Zheng Teng , Lis Stefan
Published: November 2022

Accurate and sensitive remote temperature measurement is required in a growing number of existing and emerging applications. As the technology advances and nanotechnology enters still new fields, the size of objects whose temperature needs to be controlled gets smaller and the non-contact temperature reading is the only reasonable approach. Luminescence thermometry is believed to become the technology of choice for such purposes, as it is resistant to disturbances by an electromagnetic field and the sensitivity and accuracy of measurements may be tuned for the specific requirements. Thus, whether it comes to reading temperature at cryo-range, around the room, or at high temperatures, one may design a luminescent thermometer offering high-quality measurements. This is not to say that such designing is easy to do. Even under laboratory conditions, highly-sensitive and accurate luminescent thermometers are not that frequent.

Additional problems appear when it comes to measurements over a broad range of temperatures. At first, the basic physics of luminescence processes are not conducive to the design of a luminescence thermometer offering very sensitive and accurate measurements over a broad range of temperature (a few hundred degrees, for example). On the other hand, wide-range luminescence thermometers are of interest for such important fields as aviation and space industries. Fast, accurate, and credible measurements of quickly changing temperatures are of special importance in these areas.

In this presentation, we shall report a new approach toward wide-range high-quality luminescence thermometry. Phosphors activated with either Pr3+ or Eu2+ will be examined for that purpose. Both these ions are capable of generating two types of emissions: (i) intra-configurational 5f→4f and inter-configurational 4f→4f ones. We shall prove that such phosphors may offer both broad-range and high-accuracy and high-sensitivity temperature measurements. Furthermore, we will demonstrate that the sensitivity of such sensors may be deliberately tuned to reach its maximum at temperatures where it is most needed. A few examples of such phosphors will be discussed and possible expectations for further development using this approach will be discussed.

This research was supported by the Polish National Science Center (NCN) under the grant #UMO-2018/29/B/ST5/00420.

Figure 1
(Luminescence and Display Materials Division Outstanding Achievement Award) Formulation of Radiative and Nonradiative Transitions of a Polyatomic System within Crude Adiabatic Approximation
Authors: Mishra Kailash C
Published: November 2022

The theory of radiative and nonradiative transition rates has been formulated within the framework of crude adiabatic approximation for an optical ion in a solid. The basis set consists of products of electronic wavefunctions at the equilibrium nuclear configuration in the ground electronic state, and the vibronic wavefunction associated with electronic states. The radiative and nonradiative transition rates for relaxation from the excited electronic state to a lower (ground) electronic state are obtained using the Fermi Golden rule and Boltzmann distribution of occupancy of the vibrational states in equilibrium at temperature, , of the excited electronic state. The radiative transition rates are found to be the same as that in the proper adiabatic approximation. The perturbing Hamiltonian that drives the nonradiative transition turns out to be the same as in a typical crystal field Hamiltonian, . Using this Hamiltonian, the nonradiative transition rate has been calculated for a system with a single configuration or normal coordinate, . An auxiliary function, , has been defined to describe the temperature dependence of nonradiative transition rate. At low temperatures, the maximum rate is obtained for where and represent the Huang-Rhys parameter and the energy gap between the two associated electronic states in terms of vibrational energy quantum, respectively. This is in keeping with the classical Arrhenius theory which predicts a peak at when the system relaxes thermally from the excited to the ground electronic state over an energy barrier. The dependence of on for small s-values has been studied to verify the energy gap law observed for multiphonon relaxation between excited states of rare earth ions. For most cases of interest, the temperature dependence of the nonradiative transition rates exhibits a characteristic temperature at which these rates start increasing rapidly with increasing temperature-this is usually observed for most luminescent materials. Other theoretical advantages for using the crude adiabatic theory will be pointed out during the presentation.
Investigation of Atomic Layer Deposition Post-Coating Properties of Phosphorescent SrAl2O4: Eu2+, Dy3+ Fibers Produced By Electrospinning
Authors: Karacaoglu Erkul , Ozel Faruk , Acikgoz Sabriye , Sarilmaz Adem , Yungevis Hasan , Gul Mert , Okyay Ali Kemal
Published: November 2022

In this research, phosphorescent SrAl2O4:Eu2+, Dy3+ fibers were produced by electrospinning and coated with atomic layer deposition (ALD) technique to enhance the photoluminescence (PL) properties, and water & thermal resistance. Particle form of Eu2+-activated strontium aluminate phosphors possess many remarkable features that have been reported over and over, for example, nontoxic, stable, efficient. PL enhancement and stability in water of these particles were provided by nano encapsulation process by ALD that has just been published in our previous paper. In this study, for the first time, SrAl2O4 based long persistence phosphor fibers were coated with the ALD method to both improve their PL and provide water & thermal resistance property. In this successfully carried out study, luminescence, optic, chemical and structural properties of phosphor in fiber form were investigated in detail. These improved submicron afterglow fibers which are SrAl2O4:Eu2+, Dy3+ based are promising materials for applications such as solar cells, luminescent labels for bioimaging, mechanoluminescence sensor, etc.
(Digital Presentation) Developing Mixed-Anion Mechanoluminescent Materials for Advanced Sensing Applications
Authors: Zhuang Yixi
Published: November 2022

Mechanoluminescent materials produce photon emission when subjected to mechanical action. Generally, the emission intensity is linear with the stress magnitude and shows good repeatability (except fractoluminescence). Mechanoluminescent materials have emerged as important sensing materials for the advanced mechanical sensing. Mechanical sensing based on mechanoluminescence has outstanding characteristics such as remote sensing, visualization of stress distribution, self-drive, easy preparation of flexible devices, and integration. However, the performance of mechanoluminescent materials reported so far cannot meet the application requirements of advanced mechanical sensing. In the past few years, our group developed novel mechanoluminescent materials with excellent performance based on a design route of mixed-anion structural units and expanded the applications of these materials into a variety of new sensing technologies. This report summarizes our recent work on mechanoluminescent materials with a?hope?to further strengthen exchanges and promote the development of intelligent sensing technology.
(Digital Presentation) Lead Halide Perovskite Quantum Dots for Mini-LEDs
Authors: Xuan Tongtong , Xie Rong-Jun
Published: November 2022

Lead halide perovskite quantum dots (PeQDs) are triggering a revolution in display technologies because of their near-unity photoluminescence quantum yield (PLQY), narrow band emission, wide tunable bandgap and facile synthesis. Therefore, they have been extensively investigated as color converters or emissive layers for light-emitting diode (LED) displays. However, the poor stabilities in the phase and structure of PeQDs make them hard to be practically applie, and the ultimate goal is therefore to improve the long-term stability of PeQDs. The poor stability of PeQDs originates from their inherent ionic nature. Under external conditions (such as light, heat, water and oxygen), PeQDs will decompose through interfacial reactions, leading to obvious fluorescence quenching. Although many efforts have been made to prepare robust PeQDs that are, to some extent, resistant to water, air, light, or heat exposure, he overall reliability of PeQDs shows limited improvement under the synergistic effects of multiple factors, which are usually the case in practical LED applications. We report ultrastable CsPbBr3:Sr/PbBr(OH)/molecular sieve composites (Fig. 1) with a high photoluminescence quantum yield of 75% and high overall stability when exposed to water, blue light and heat, owing to (i) the increased formation energy of CsPbBr3 PeQDs by Sr doping and (ii) good encapsulation by PbBr(OH) and molecular sieves. These composites maintain 54% of their initial intensity after being aged at 85°C and 150 mW/cm2 for 720 min, which is superior to commercial green CdSe-based QDs. These promising composites are then used to produce Mini-LED backlights with a high luminous efficacy of 86 lm/W and a color area of ~124% of the National Television Standards Committee or 93% of the Rec. 2020 standards by combining them with red CdSe/CdS/ZnS QDs and a blue Mini-LED chip. We believe that highly reliable PeQDs can be achieved by building well-designed composite structures, thus enabling them to be practically applied in emerging lighting and displays.

Figure 1
Silver Nanoparticle Labels for Electrochemical Detection of Bioassays
Authors: Walgama Charuksha , Pollok Nicole , Peng Yi , Crooks Richard
Published: November 2022

Electrochemistry plays a major role in immunosensor development because of its higher sensitivity, simplicity, portability, and rapidity compared to more common enzymatic, fluorescent and radioactive labelling methods. Silver nanoparticles (AgNPs) have been identified as potential electrochemical labels for such immunoassays. Characterizing the composition, size, shape, and surface modifications of the AgNP is important to achieve expected analytical performance of the bio assay. Here we are interested in studying the effect of nanoparticle shape towards the electrochemical detection of a metallo-immunoassay using Au-Ag galvanic exchange (GE) reaction followed by anodic stripping voltammetry. We observe that during GE between electrogenerated Au3+ and the Ag labels, a thin shell of Au forms on the surface of the NP and prevent further exchange. This shell is more porous when GE proceeds on silver nanocubes (AgNCs) compared to spherical silver nanoparticles (sAgNPs), and therefore, more exchange occurs when using AgNCs. More interestingly, optimizing the ratio of the two types of AgNP labels, we could able to decrease the LOD of a biological assay designed to detect a heart failure biomarker (NT-proBNP) without compromising the dynamic range compared to using either of the two labels independently. This made it possible to achieve the clinically relevant range for NT-proBNP analysis used by physicians for heart failure risk stratification.
(Digital Presentation) Electrochemical Single Impact Method for Electroactive Bacterial Detection Onto Carbon Ultramicroelectrode
Authors: Smida Hassiba , Thobie-Gautier Christine , Boujtita Mohammed , Lebegue Estelle
Published: November 2022

This work aims to design a high sensitivity and selectivity biosensor based on the electrochemistry of single impacts onto ultramicroelectrode (UME) to detect and identify various bacterial strains. The main objective is to establish a unique electrochemical signature for each bacterial cell through the individual impact event signal on the surface of the UME [1, 2]. First, we focus on the detection of well-known electroactive Gram-negative bacteria such as Shewanella oneidensis in order to be able to selectively detect these different single cells. In this case, the strategy currently used is to record a chronoamperometric curve in an aqueous potassium phosphate buffer (pH = 7.4) solution containing a redox probe at an UME polarized at the oxidation or reduction potential of the electrochemical active aqueous species and to observe a “current step” when one bacterium impacts the UME, corresponding to a “blocking effect” [3] (Figure A). The response signal expected from single bacterium collision may also be a “current spike” corresponding to either the own electrochemical activity of the bacterium toward the redox probe and the UME applied potential or a “bouncing effect” of the bacterium which does not stick onto UME surface (Figure B).

In order to be able to identify the type of bacterial cell striking the UME surface, an adapted functionalization (covalent grafting via reduction of diazonium aryl salts) with appropriate affinity (bio)chemical species such as antibodies or aptamers could be performed. This strategy could confer to the UME surface a selectivity of the signal generated during single impacts. For example, the electro-grafting of diazo-pyridinium cations for microbial fuel cell electrodes showed to promote and improve the development of bacterial electroactive films [4].

[1] E. Lebègue, N. L. Costa, R. O. Louro, F. Barrière, J. Electrochem. Soc. 16 (2020) 105501

[2] A. T. Ronspees, S. N.Thorgaard, Electrochimica Acta. 278 (2018) 412-420

[3] G. Guanyue, W. Dengchao, B. Ricardo, Z. Jinfang, M. Michael V. Anal. Chem. 90 (2018) 12123−12130

[4] H. Smida, E. Lebègue, J-F. Bergamini, F. Barrière, C. Lagrost, Bioelectrochemistry. 120 (2018) 157-165

Figure 1