Enhanced CO2 electrolysis through Mn substitution coupled with Ni exsolution in lanthanum calcium titanate electrodes

Funding: This work was financially supported by the Industrial Decarbonisation Research and Innovation Centre. Further support was kindly provided by EPSRC, under research grant numbers EP/L017008/1, EP/R023751/1 and EP/T019298/1.In this study, perovskite oxides La0.3Ca0.6Ni0.05MnxTi0.95−xO3−γ (x = 0, 0.05, 0.10) are investigated as potential solid oxide electrolysis cell cathode materials. The catalytic activity of these cathodes toward CO2 reduction reaction is significantly enhanced through the exsolution of highly active Ni nanoparticles, driven by applying a current of 1.2 A in 97% CO2 – 3% H2O. The performance of La0.3Ca0.6Ni0.05Ti0.95O3−γ is notably improved by co-doping with Mn. Mn dopants enhance the reducibility of Ni, a crucial factor in promoting the in situ exsolution of metallic nanocatalysts in perovskite (ABO3) structures. This improvement is attributed to Mn dopants enabling more flexible coordination, resulting in higher oxygen vacancy concentration, and facilitating oxygen ion migration. Consequently, a higher density of Ni nanoparticles is formed. These oxygen vacancies also improve the adsorption, desorption, and dissociation of CO2 molecules. The dual doping strategy provides enhanced performance without degradation observed after 133 h of high-temperature operation, suggesting a reliable cathode material for CO2 electrolysis.Peer reviewe

EINFLUSSE DES PRAGER PARLERKREISES AUF DIE ARCHITEKTONISCHE PLASTIK AUS ILOK

In elem maler ischen syrmischen Stacltchen I lok ani h o hen Ufer cler Donau, umgeben von mi t telalterlichen Mauern, steht clie trot z cler t u r k ischen Her rschaft ( 1 526.— 1688.) erhalten gebliebene Franziskanerkirche cles hl . Johann Kapistran. Diese Kirche, die f ruher ei n ancleres Patrozinium hat te, wurde einige Male umgebaut ,im 18. Jh. barockisiert, und Anfang cles 20 Jhs. neugotisch restauriert. Bei clieser Gelegenheit wurcle ihr architektonisch- plastischer Schmuck e n t fernt , c ler s i c ht s eit dem Jahr 1912. in Zagreb befindet ( jetzt im Hi stor ischen Museum) . ln der Ki rche verblieb cine Konsolemit cler Jahreszahl 1468., nach welcher vor e iner halben Jahrhundert J. Br unšmid auch die Ubrigen erhaltenen Konsolen in clie zweite Halfte des 15. Jhs. clatierte. De r S t i l e i n iger von ihnen spr icht j ecloch fur cine andere Entstehungszeit. Es werden anschliessend st i l istische Merkmale dreier clieser Denkmaler untersucht: einer Konsole mit Laubwerk (42x42x59 cm), einer Konsole mi t Teufelskopf (46x37x47 cm) und einer Konsole mit dem Kopfe eines Monstrums (29x48x48 cna), die alle aus Sanclstein gemeisselt sincI. Ein Vergleich mi t Ko nsolen in cler Kathedrale i n Prag, sowie auch nai t v erwancltem Mater ial i n Zagreb, Slowenien, Osterreich uncI i n Ungarn (Budapest), welches unter elena Einfluss c ler Werkstatt der Par ler i n Pr ag entstanden i s t , z e i gt , class auch clie Konsolen aus Ilok Zuge aufweisen, die fur elen von der prager Parlerwerkstatt gemeisselten architektonisch-plastischen Schmuck kennzeichnend sind. Es wircl vorausgesetzt, class cliese Einflusse nicht auf di rektem Wege von Prag nach I lok gelang sincI, sondern uber Buclapest. Dort haben — nach Gerevich — n ach elem Jahre 1385.,nachclem c!er Chor cler Katheclrale in Prag fer t iggestellt war , al tere Meister cler ersten Generation gearbeitet ( si e konnten etwa 60 Jahre alt gewesen sein). Diese Meister sincI wahrscheinlich auf j ener alteren St i lstufe stehengeblieben, die ihr e Werke f u r clie prager Katheclrale kennzeichnet, bevor sie in di e Wel t h i nausz ogen. Danti t k o nnt e ma n d i e archaischen Zuge der Konsolen aus Ilok erklaren, clie — b edingt durch clieubrigen Zustancle im Lancle — t rot z ihrer archaischen Zuge in clieser provinziellen Umgebung in c(er Zeit cles Ubergangs vom 14. ins 15. Jh. ent stanclen sein konnten. Als Vermi t t ler kamen Konig Sigisniuncl von Luxemburg uncI Nikola Gor janski i n Bet racht . Konig Sigismund war f i m J a hre 1394. elen Aufstancl Paližna\u27s uncI der Br uder Ho r vat n iecle, und I ehrte nach cler Schfacht bei Nikopolis im Jahre 1397. aus cler Gerangenschaft i n s ei n L anel zuruck. Nikola Gor janski, Sigismuncl\u27s treuer Anhanger, war Banus von Kroatien (1397.1401.), uncI sei t elem Jahr e 1402. der ma cht ige Palatin von Ungarn, elem unter v ielen ancleren Gutern auch I lok gehor te. Bis jetzt war Zagreb al s cler sgcllichste Punkt bekannt, l>is zu welchem clie Ein f lusse cler beruhnnten Werkstatt cler Parl in Prag reichten. Nach elem Dargelegten ware jetzt I lok i n suclostlicher Richtung cler entfernteste Punkt i n cler kunstlerischen Geographie Europas, bi s z u we l chem s ic h d i e Erfahrungen <lieser Werkstatt er st reckte

The development of fuel electrodes for high temperature solid oxide cells

Our energetic matrix is currently based on finite fossil fuels, leading to climate change and increasing hazardous air pollutants. Nevertheless, solid oxide cells have emerged as a feasible and profitable route for energy generation. Solid oxide electrolysis cells can convert the excess electrical energy into chemical energy, thereby decoupling the transport fuels and chemicals production from today’s fossil fuels, while solid oxide fuel cells can convert chemical energy back into electricity, thus balancing energy availability and demand. Solid oxide electrolysis cells afford an opportunity for upgrading biogas through the internal dry reforming of biogas and carbon dioxide electrolysis, producing hydrogen and carbon monoxide. Solid oxide electrolysis cells with conventional Ni-YSZ cermet fuel electrode and yttria stabilized zirconia electrolyte were constructed and tested on the direct feed of simulated biogas mixture (i.e. CH₄/CO₂ = 60/40, 50/50 and 40/60) at 850 °C. Cell performance and outlet gases measurements were carried out under open-circuit and closed-circuit conditions. The current densities at 1.8 V are -0.448, -0.678 and -0.876 A cm⁻² for the gas mixtures of CH₄/CO₂= 60/40, 50/50 and 40/60, respectively. The short term durability tests were performed in these three gas mixtures at 850 °C and 1.4 V. The cell fed with high CO₂ content demonstrates stable performance. No carbon deposition was observed on the Ni-YSZ fuel electrode surface, which might be due to not reaching the thermodynamic equilibrium and the reverse Boudouard reaction. Nonstoichiometric perovskites with active metal nanoparticles exsolved on the surface have been proposed as the promising fuel electrode in solid oxide cells. Here, La₀.₄₀Ca₀.₄₀TiO₃ and La₀.₄₃Ca₀.₃₇MTi₁-O₃-γ (M = Ni₀.₀₅, Ni₀.₁₀, Mn₀.₁₀, Co₀.₁₀, Ni₀.₀₅Mn₀.₀₅, and Ni₀.₀₅Co₀.₀₅) perovskite oxides were synthesized. The in-situ exsolution of Ni, Co and NiCo metal nanoparticles from the perovskite oxide parents was successfully according to the X-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy. The results demonstrate that the exsolved metal nanoparticles can enhance the electrical conductivity, catalytic activity toward the hydrogen oxidation end carbon dioxide reduction. The cell performance can be improved by employing high voltage electrochemical reduction and extending the electrochemical reduction time. The best cell performance in 3% H₂O/H₂ was achieved by La₀.₄₃Ca₀.₃₇Ni₀.₁₀Ti₀.₉₀O₃-γ, exhibiting the maximum power density of 1.50 W cm⁻² at 900 °C. La₀.₄₃Ca₀.₃₇Co₀.₁₀Ti₀.₉O₃-γ based solid oxide electrolysis cell displays the highest current density of 0.856 A cm⁻² at 1.4 V

The development of fuel electrodes for high temperature solid oxide cells

Our energetic matrix is currently based on finite fossil fuels, leading to climate change and increasing hazardous air pollutants. Nevertheless, solid oxide cells have emerged as a feasible and profitable route for energy generation. Solid oxide electrolysis cells can convert the excess electrical energy into chemical energy, thereby decoupling the transport fuels and chemicals production from today’s fossil fuels, while solid oxide fuel cells can convert chemical energy back into electricity, thus balancing energy availability and demand.Solid oxide electrolysis cells afford an opportunity for upgrading biogas through the internal dry reforming of biogas and carbon dioxide electrolysis, producing hydrogen and carbon monoxide. Solid oxide electrolysis cells with conventional Ni-YSZ cermet fuel electrode and yttria stabilized zirconia electrolyte were constructed and tested on the direct feed of simulated biogas mixture (i.e. CH₄/CO₂ = 60/40, 50/50 and 40/60) at 850 °C. Cell performance and outlet gases measurements were carried out under open-circuit and closed-circuit conditions. The current densities at 1.8 V are -0.448, -0.678 and -0.876 A cm⁻² for the gas mixtures of CH₄/CO₂= 60/40, 50/50 and 40/60, respectively. The short term durability tests were performed in these three gas mixtures at 850 °C and 1.4 V. The cell fed with high CO₂ content demonstrates stable performance. No carbon deposition was observed on the Ni-YSZ fuel electrode surface, which might be due to not reaching the thermodynamic equilibrium and the reverse Boudouard reaction.Nonstoichiometric perovskites with active metal nanoparticles exsolved on the surface have been proposed as the promising fuel electrode in solid oxide cells. Here, La₀.₄₀Ca₀.₄₀TiO₃ and La₀.₄₃Ca₀.₃₇M&#x1d465;Ti₁-&#x1d465;O₃-γ (M = Ni₀.₀₅, Ni₀.₁₀, Mn₀.₁₀, Co₀.₁₀, Ni₀.₀₅Mn₀.₀₅, and Ni₀.₀₅Co₀.₀₅) perovskite oxides were synthesized. The in-situ exsolution of Ni, Co and NiCo metal nanoparticles from the perovskite oxide parents was successfully according to the X-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy. The results demonstrate that the exsolved metal nanoparticles can enhance the electrical conductivity, catalytic activity toward the hydrogen oxidation end carbon dioxide reduction. The cell performance can be improved by employing high voltage electrochemical reduction and extending the electrochemical reduction time. The best cell performance in 3% H₂O/H₂ was achieved by La₀.₄₃Ca₀.₃₇Ni₀.₁₀Ti₀.₉₀O₃-γ, exhibiting the maximum power density of 1.50 W cm⁻² at 900 °C. La₀.₄₃Ca₀.₃₇Co₀.₁₀Ti₀.₉O₃-γ based solid oxide electrolysis cell displays the highest current density of 0.856 A cm⁻² at 1.4 V

Conformation and dynamics of the mammalian chromosome

Thesis: S.M., Massachusetts Institute of Technology, Department of Biology, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 29-30).The control of transcription represents a fundamental, initial mechanism by which the regulation of gene expression is implemented. However, while much research has been done on the biochemistry and cellular function of transcription, comparatively little is known on the dynamics of transcriptional mechanisms, their impact on chromatin structure, and concomitant functional consequences. Employing chromatin immunoprecipitation measurements, we report progress towards this goal. We characterize the ensemble chromosome conformation in mouse embryonic stem cells, by measuring interaction, or contact, probabilities between distal genomic loci. We map and describe chromosome loops, consisting of two interacting CTCF sites co-bound by cohesin, that maintain the expression of genes known to promote cell identity, and restrict the expression of genes specifying repressed developmental lineages.by Lyndon N. Zhang.S.M

Examine operando generated Ni-based alloy nanomaterials as fuel electrode in solid oxide cells

In this work, we focus on investigating the titanate perovskites with exsolved Ni-Co alloy nanocatalysts as fuel electrode of solid oxide cells (SOCs), particularly on operando generating these nanomaterials via applying a potential bias in CO2 electrolysis operating conditions. Three compositions of titanate perovskite were examined, including La0.43Ca0.37Ti0.94Ni0.06O3-δ (LCT-Ni6), La0.43Ca0.37Ti0.94Ni0.03Co0.03O3-δ (LCT-Ni3Co3), and La0.43Ca0.37Ti0.90Ni0.05Co0.05O3-δ (LCT-Ni5Co5). Various techniques, including X-ray diffraction, thermogravimetric analysis, DC conductivity measurement etc., were applied to study the crystal structure, reduction behavior, conductivity property, and microstructure of these materials. SOCs with these titanate fuel electrodes were fabricated and evaluated, with emphasis placed on operando generation of active nanomaterials through electrochemical switching in pure CO2 atmosphere, and on understanding the materials properties linking to their microstructure and performance towards CO2 electrolysis and H2 fuel cell

Exsolved materials for CO2 reduction in high-temperature electrolysis cells

Electrochemical reduction of CO2 into valuable fuels and chemicals has become a contemporary research area, where the heterogeneous catalyst plays a critical role. Metal nanoparticles supported on oxides performing as active sites of electrochemical reactions have been the focus of intensive investigation. Here, we review the CO2 reduction with active materials prepared by exsolution. The fundamental of exsolution was summarized in terms of mechanism and models, materials, and driven forces. The advances in the exsolved materials used in high-temperature CO2 electrolysis were catalogued into tailored interfaces, synergistic effects on alloy particles, phase transition, reversibility and electrochemical switching

Control of Cell Identity Genes Occurs in Insulated Neighborhoods in Mammalian Chromosomes

The pluripotent state of embryonic stem cells (ESCs) is produced by active transcription of genes that control cell identity and repression of genes encoding lineage-specifying developmental regulators. Here, we use ESC cohesin ChIA-PET data to identify the local chromosomal structures at both active and repressed genes across the genome. The results produce a map of enhancer-promoter interactions and reveal that super-enhancer-driven genes generally occur within chromosome structures that are formed by the looping of two interacting CTCF sites co-occupied by cohesin. These looped structures form insulated neighborhoods whose integrity is important for proper expression of local genes. We also find that repressed genes encoding lineage-specifying developmental regulators occur within insulated neighborhoods. These results provide insights into the relationship between transcriptional control of cell identity genes and control of local chromosome structure.National Institutes of Health (U.S.) (Grant HG002668