The development of alternative cathodes for high temperature solid oxide electrolysis cells

This study mainly explores the development of alternative cathode materials for the electrochemical reduction of CO₂ by high temperature solid oxide electrolysis cells (HTSOECs), which operate in the reverse manner of solid oxide fuel cells (SOFCs). The conventional Ni-yttria stabilized zirconia (YSZ) cermets cathode suffered from coke formation, whereas the perovskite-type (La, Sr)(Cr, Mn)O₃ (LSCM) oxide material displayed excellent carbon resistance. Initial CO₂ electrolysis performance tests from different cathode materials prepared by screen-printing showed that LSCM based cathode performed poorer than Ni-YSZ cermets, due to non-optimized microstructure. Efforts were made on microstructure modification of LSCM based cathodes by means of various fabrication methods. Among the LSCM/YSZ graded cathode, extra catalyst (including Pd, Ni, CeO₂, and Pt) aided LSCM/GDC (Gd₀.₁Ce₀.₉O₁.₉₅) cathode, LSCM impregnated YSZ cathode, and GDC impregnated LSCM cathode, the GDC impregnated LSCM cathode, with porous LSCM as backbone for finely dispersed GDC nanoparticles, was found to possess the desired microstructure for CO₂ splitting reaction via SOEC. Incorporating of 0.5wt% Pd into GDC impregnated LSCM cathode gave rise to an Rp of 0.24 Ω cm² at open circuit voltage (OCV) at 900°C in CO₂-CO 70-30 mixture, comparable with the Ni/YSZ cermet cathode operated in the identical conditions. Meanwhile, the cathode kinetics and possible mechanisms of the electrochemical reduction of CO₂ were studied, and factors including CO₂/CO composition, operation temperature and potential were taken into account. The current-to-chemical efficiency of CO₂ electrolysis was evaluated with gas chromatography (GC). The high performance Pd and GDC co-impregnated LSCM cathode was also applied for CO₂ electrolysis without protective CO gas in feed. This cathode also displayed superb performance towards CO₂ electrochemical reduction under SOEC operation condition in CO₂/N₂ mixtures, though it had OCV as low as 0.12V at 900°C. The LSCM/GDC set of SOEC cathode materials were investigated in the application of steam electrolysis and H₂O-CO₂ co-electrolysis as well. For the former, adequate supply of steam was essential to avoid the appearance of S-shaped I-V curves and limited steam transport. The 0.5wt% Pd and GDC co-infiltrated LSCM material has been found to be a versatile cathode with high performance and good durability in SOEC operations

Modification of the LSCM-GDC cathode to enhance performance for high temperature CO2 electrolysis via solid oxide electrolysis cells (SOECs)

This work was funded by Overseas Research Students Awards Scheme (ORSAS), University of St Andrews and by RCUK Energy Supergen programme on H-Delivery and EPSRC Platform and Senior fellowship programs (EP/G01244X/1). JTSI acknowledges the Wolfson Research Merit Award (WRMA 2012/R2).Extensive efforts have been made to find new fuel electrode materials for solid oxide cells with high activity and durability to provide more robust materials than the state-of-the-art material, the Ni-cermet . In the present study, a Ni-free cathode is presented with competitive performance and higher durability than a well-behaved Ni-YSZ cermet for CO2 electrolysis via SOEC. A (La, Sr)(Cr, Mn)O3/(Gd, Ce)O2 (LSCM/GDC) cathode fabricated by vacuum infiltration of GDC nitrate solutions into a LSCM/YSZ (8 mol% yttria stabilised zirconia) skeleton is reported. A porous YSZ layer introduced between the dense electrolyte and this cathode helps to maintain a good cathode/electrolyte interface, whilst the nano-structured GDC phase introduced on the surface of LSCM/YSZ backbone is advantageous to boost the cathode electrochemical and catalytic properties towards CO2 reduction by SOEC. Vacuum impregnation therefore offers an effective means to modify the microstructure of LSCM/GDC material set used as cathode for high temperature CO2 electrolysis. With the doping of Pd co-catalyst after GDC impregnation, the cathode activity of the GDC impregnated LSCM material is further enhanced for high temperature CO2 electrolysis, and the 0.5wt% Pd and GDC co-impregnated LSCM cathode achieves an Rp value of 0.24 Ω cm2 at OCV at 900oC in CO2-CO 70-30 mixture, a comparable level to a high performance Ni-YSZ cathode operated in the identical conditions.PostprintPeer reviewe

Application of infiltrated LSCM-GDC oxide anode in direct carbon/coal fuel cells

The authors would like to thank the European project ‘Efficient conversion of coal to electricity- Direct Coal Fuel Cells’, funded by the Research Fund for Coal & Steel (RFC-PR-10007).Hybrid direct carbon/coal fuel cells (HDCFCs) utilise an anode based upon a molten carbonate salt with an oxide conducting solid electrolyte for direct carbon/coal conversion. They can be fuelled by a wide range of carbon sources, and offer higher potential chemical to electrical energy conversion efficiency and have the potential to decrease CO2 emissions compared to coal-fired power plants. In this study, the application of (La, Sr)(Cr, Mn)O3 (LSCM) and (Gd, Ce)O2 (GDC) oxide anodes was explored in a HDCFC system running with two different carbon fuels, an organic xerogel and a raw bituminous coal. The electrochemical performance of the HDCFC based on a 1–2 mm thick 8 mol% yttria stabilised zirconia (YSZ) electrolyte and the GDC–LSCM anode fabricated by wet impregnation procedures was characterized and discussed. The infiltrated oxide anode showed a significantly higher performance than the conventional Ni–YSZ anode, without suffering from impurity formation under HDCFC operation conditions. Total polarisation resistance (Rp) reached 0.8–0.9 Ω cm2 from DCFC with an oxide anode on xerogel and bituminous coal at 750 °C, with open circuit voltage (OCV) values in the range 1.1–1.2 V on both carbon forms. These indicated the potential application of LSCM–GDC oxide anode in HDCFCs. The chemical compatibility of LSCM/GDC with carbon/carbonate investigation revealed the emergence of an A2BO4 type oxide in place of an ABO3 perovskite structure in the LSCM in a reducing environment, due to Li attack as a result of intimate contact between the LSCM and Li2CO3, with GDC being stable under identical conditions. Such reaction between LSCM and Li2CO3 was not observed on a LSCM–YSZ pellet treated with Li–K carbonate in 5% H2/Ar at 700 °C, nor on a GDC–LSCM anode after HDCFC operation. The HDCFC durability tests of GDC–LSCM oxide on a xerogel and on raw bituminous coal were performed under potentiostatic operation at 0.7 V at 750 °C. The degradation mechanisms were addressed, especially on raw coal.PostprintPeer reviewe

La and Ca-doped A-site deficient strontium titanates anode for electrolyte supported direct methane solid oxide fuel cell

The authors thank UKIERI and DST for financial help during execution of the project.Nickel-yttria stabilized zirconia (Ni-YSZ) cermet anodes for solid oxide fuel cells (SOFC) possesses excellent catalytic properties and stability for H2 oxidation but not for hydrocarbons as it results in fast carbon deposition in absence of excess steam. In the present work, A-site deficient porous LSCTA- (La0.2Sr0.25Ca0.45TiO3) anode has been fabricated using the environment friendly, aqueous tape casting method followed by the same procedure for the dense YSZ electrolyte and YSZ porous scaffold as cathode matrix. The anode, electrolyte, and porous cathode matrix have been laminated together and sintered up to 1350°C. After sintering, nitrate precursors of La, Sr, Co and Fe are infiltrated inside the porous YSZ cathode matrix to form the perovskite phases of La0.8Sr0.2CoO3 (LSC) and La0.8Sr0.2FeO3 (LSF). The as fabricated electrolyte supported SOFCs have been tested in H2 and CH4 fuel at 800°C. The electrolyte supported cell 15%LSF-5% LSC-YSZ/YSZ/4%Ni-6%CeO2-LSCTA- gives maximum power density of 328 mW cm−2 for 3 h in H2, but in CH4 the performance decreased to 165 mW cm−2 even though a sustained open circuit voltage of ∼1 V obtained during H2 and CH4 operation. The morphology of the anode before and after cell testing has been analyzed using scanning electron microscope followed by X-ray diffraction studies to understand phase changes during fabrication and testing.PostprintPeer reviewe

Electrical reduction of perovskite electrodes for accelerating exsolution of nanoparticles

This work was supported through the Leading Graduate School Program: Academy for Co-creative Education of Environment and Energy Science (ACEEES) funded by the Ministry of Education, Culture, Sports, Science and Technology (MEXT, Japan).Growth of finely dispersed nanocatalysts by exsolution of metal nanoparticles from perovskite oxides under reducing conditions at elevated temperature is a promising approach of producing highly active catalytic materials. An alternative method of exsolution using an applied potential has been recently shown to potentially accelerate the exsolution process of nanoparticles that can be achieved in minutes rather than the hours required in chemical reduction. In the present study, we investigate exsolution of nanoparticles from perovskite oxides of La0.43Ca0.37Ni0.06Ti0.94O3-γ (LCTNi) and La0.43Ca0.37Ni0.03Fe0.03Ti0.94O3-γ (LCTNi-Fe) under applied potentials in carbon dioxide atmosphere. The impedance spectra of single cells measured before and after electrochemical poling at varying voltages showed that the onset of exsolution process occurred at 2 V of potential reduction. An average particle size of the exsolved nanoparticles observed after testing using a scanning electron microscopy was about 30–100 nm. The cells with the reduced electrodes exhibited desirable electrochemical performances not only in pure carbon dioxide (current density of 0.37 A cm−2 for LCTNi and 0.48 A cm−2 for LCTNi-Fe at 1.5 V) but also in dry hydrogen (0.36 W cm−2 for LCTNi and 0.43 W cm−2 for LCTNi-Fe).PostprintPeer 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

Improved electrochemical performance of LiCoPO4 using eco-friendly aqueous binders

EJK would like to thank the Alistore ERI for the award of a studentship. The authors thank EPSRC Capital for Great Technologies Grant EP/L017008/1.The electrochemical performance of LiCoPO4 (LCP) as a high-voltage positive electrode for lithium-ion batteries is significantly improved by using the aqueous binder sodium carboxymethyl cellulose (CMC). The CMC not only provides a uniform electrode surface as shown by scanning electron microscopy and elemental mapping, but also suppresses the degradation of LiCoPO4 by scavenging HF in the electrolyte solution as demonstrated by FT-IR. In comparison with other water-soluble binders such as sodium alginate (ALG) and polyacrylic acid sodium salt (PAA), the homogeneous distribution of CMC within the electrodes accompanied by high accessibility of carboxylate groups in CMC are shown to be crucial factors to achieve enhanced performance with an excellent capacity retention of 94% after 20 cycles at a rate of C/10.PostprintPostprintPeer reviewe

Metal-oxide interactions for infiltrated Ni nanoparticles on A-site deficient LaxSr1 − 3x/2TiO3

The authors would like to thank EPSRC Platform (Grant EP/K015540/1) and the Royal Society for Wolfson Merit Award (WRMA 2012/R2) for funding. We also acknowledge support from China Scholarship Council (No. 201406690029).Enhancing the stability of introduced metal catalysts on oxide surfaces is a major issue for infiltrated anodes in Solid Oxide Cells (SOC) and other related catalysis field. Stoichiometric SrTiO3 (STO) and A-site cation deficient LaxSr1 − 3x/2TiO3 (LST) were compared to investigate the influence of stoichiometry upon the contact between metal and oxide, in order to improve the bonding of catalyst and substrate. Optimization of oxidizing and reducing temperatures for Ni infiltration processes was performed to get good nanoparticles distribution on the perovskite surface. Thermogravimetry (TG) and X-ray diffraction (XRD) analysis showed the formation of NiO, Ni after oxidation and reduction, respectively. Energy Dispersive Spectroscopy (EDS) on a Transmission Electron Microscopy (TEM) was employed to characterize the nickel nanoparticles on the LST surface. No obvious elemental transfer happened between Ni and LST. The TEM images showed Ni nanoparticles bonded well to the A-site deficient perovskite with large contact area. TG analysis in reducing atmosphere indicates interactions between metal-oxide interactions in deficient samples. This may improve the Ni distribution on perovskite surface and further control the growth of Ni particles when heated at extreme temperature.PostprintPeer reviewe

3D Numerical Simulation-Based Targeting of Skarn Type Mineralization within the Xuancheng-Magushan Orefield, Middle-Lower Yangtze Metallogenic Belt, China

Recent exploration has identified a series of Cu-Mo skarn deposits within the Xuancheng-Magushan orefield. The orefield forms part of the Nanling-Xuancheng mining district, which is located within the Middle-Lower Yangtze River Metallogenic Belt (MLYRMB) of central-eastern China. However, this area contains thick and widespread unprospective sedimentary cover sequences that have impeded traditional approaches to mineral exploration. This study presents the results of 3D numerical simulation modeling that identifies possible mineral exploration targets within the entire Xuancheng-Magushan orefield. This modeling enables the identification of unexplored areas with significant exploration potential that are covered by thick sedimentary sequences that cannot be easily explored using traditional exploration approaches. This study outlines the practical value of 3D numerical simulation-based targeting in areas with thick sedimentary cover sequences and uses the Flac(3D) software package to couple processes involved in ore formation such as stress, pressure, and heat transfer. Here, we use volumetric strain increments calculated during numerical modeling as the thermodynamic representation of the generation of space during prograde skarn formation, with this space filed by sulfides either penecontemporaneously or soon after magmatism. This process occurred during retrograde hydrothermal ore formation and the genesis of the skarn-type mineralization in this area. The results of the volumetric strain increment calculated during this numerical modeling study matches the distribution of known mineralization as well as delineating eight potential targets that have not yet been explored but represent areas of significant exploration potential within the Xuancheng-Magushan orefield, indicating these targets should be considered prospective for future mineral exploration. One of these targets was also identified during our previous Comsol-based numerical modeling of the formation of the Magushan Cu-Mo skarn deposit. The fact that this area has been identified as prospective using two different numerical modeling methods indicates that this area should be prioritized for future exploration and also validates the numerical modeling approaches used here and in our previous research that more specifically focused on the Magushan skarn deposit. Overall, our study indicates that prospectivity modeling using 3D numerical simulation-based approaches can be both effective and economical and should be considered an additional tool for future mineral exploration to reduce exploration risks when targeting mineralization in areas with thick and unprospective sedimentary cover sequences

Coxsackievirus A6 Induces Cell Cycle Arrest in G0/G1 Phase for Viral Production

Recent epidemiological data indicate that outbreaks of hand, foot, and mouth disease (HFMD), which can be categorized according to its clinical symptoms as typical or atypical, have markedly increased worldwide. A primary causative agent for typical HFMD outbreaks, enterovirus 71 (EV71), has been shown to manipulate the cell cycle in S phase for own replication; however, it is not clear whether coxsackievirus (CVA6), the main agent for atypical HFMD, also regulates the host cell cycle. In this study, we demonstrate for the first time that CVA6 infection arrests the host cell cycle in G0/G1-phase. Furthermore, synchronization in G0/G1 phase, but not S phase or G2/M phase, promotes viral production. To investigate the mechanism of cell cycle arrest induced by CVA6 infection, we analyzed cell cycle progression after cell cycle synchronization at G0/G1 or G2/M. Our results demonstrate that CVA6 infection promotes G0/G1 phase entry from G2/M phase, and inhibits G0/G1 exit into S phase. In line with its role to arrest cells in G0/G1 phase, the expression of cyclinD1, CDK4, cyclinE1, CDK2, cyclinB1, CDK1, P53, P21, and P16 is regulated by CVA6. Finally, the non-structural proteins of CVA6, RNA-dependent RNA polymerase 3D and protease 3C , are demonstrated to be responsible for the G0/G1-phase arrest. These findings suggest that CVA6 infection arrested cell cycle in G0/G1-phase via non-structural proteins 3D and 3C, which may provide favorable environments for virus production