Unintended cation crossover influences CO2 reduction selectivity in Cu based zero gap electrolysers

Membrane electrode assemblies enable CO2 electrolysis at industrially relevant rates, yet their operational stability is often limited by formation of solid precipitates in the cathode pores, triggered by cation crossover from the anolyte due to imperfect ion exclusion by anion exchange membranes. Here we show that anolyte concentration affects the degree of cation movement through the membranes, and this substantially influences the behaviors of copper catalysts in catholyte free CO2 electrolysers. Systematic variation of the anolyte KOH or KHCO3 ionic strength produced a distinct switch in selectivity between either predominantly CO or C2 products mainly C2H4 which closely correlated with the quantity of alkali metal cation K crossover, suggesting cations play a key role in C C coupling reaction pathways even in cells without discrete liquid catholytes. Operando X ray absorption and quasi in situ X ray photoelectron spectroscopy revealed that the Cu surface speciation showed a strong dependence on the anolyte concentration, wherein dilute anolytes resulted in a mixture of Cu and Cu0 surface species, while concentrated anolytes led to exclusively Cu0 under similar testing conditions. These results show that even in catholyte free cells, cation effects including unintentional ones significantly influence reaction pathways, important to consider in future development of catalysts and device

Facile Synthesis of Hierarchical CuS and CuCo2S4 Structures from an Ionic Liquid Precursor for Electrocatalysis Applications

Covellite phase CuS and carrollite phase CuCo2S4 nano and microstructures were synthesized from tetrachloridometallate based ionic liquid precursors using a novel, facile, and highly controllable hot injection synthesis strategy. The synthesis parameters including reaction time and temperature were first optimized to produce CuS with a well controlled and unique morphology, providing the best electrocatalytic activity toward the oxygen evolution reaction OER . In an extension to this approach, the electrocatalytic activity was further improved by incorporating Co into the CuS synthesis method to yield CuCo2S4 microflowers. Both routes provide high microflower yields of gt;80 wt . The CuCo2S4 microflowers exhibit a superior performance for the OER in alkaline medium compared to CuS. This is demonstrated by a lower onset potential amp; 8764;1.45 V vs RHE 10 mA cm2 , better durability, and higher turnover frequencies compared to bare CuS flowers or commercial Pt C and IrO2 electrodes. Likely, this effect is associated with the presence of Co3 sites on which a better adsorption of reactive species formed during the OER e.g., OH, O, OOH, etc. can be achieved, thus reducing the OER charge transfer resistance, as indicated by X ray photoelectron spectroscopy and electrochemical impedance spectroscopy measurement

Poly ionic liquid nanovesicles via polymerization induced self assembly and their stabilization of Cu nanoparticles for tailored CO2 electroreduction

Herein, we report a straightforward, scalable synthetic route towards poly ionic liquid PIL homopolymer nanovesicles NVs with a tunable particle size of 50 to 120 nm and a shell thickness of 15 to 60 nm via one step free radical polymerization induced self assembly. By increasing monomer concentration for polymerization, their nanoscopic morphology can evolve from hollow NVs to dense spheres, and finally to directional worms, in which a multilamellar packing of PIL chains occurred in all samples. The transformation mechanism of NVs internal morphology is studied in detail by coarse grained simulations, revealing a correlation between the PIL chain length and the shell thickness of NVs. To explore their potential applications, PIL NVs with varied shell thickness are in situ functionalized with ultra small 1 amp; 8764; 3 nm in size copper nanoparticles CuNPs and employed as electrocatalysts for CO2 electroreduction. The composite electrocatalysts exhibit a 2.5 fold enhancement in selectivity towards C1 products e.g., CH4 , compared to the pristine CuNPs. This enhancement is attributed to the strong electronic interactions between the CuNPs and the surface functionalities of PIL NVs. This study casts new aspects on using nanostructured PILs as new electrocatalyst supports in CO2 conversion to C1 product

Tailor designed binary Ni Cu nano dendrites decorated 3D carbon felts for efficient glycerol electrooxidation

Herein, 3D Carbon Felt CF are decorated with nickel copper Ni Cu CF bimetallic nanostructures through either sequential or co electrodeposition tactics. Their catalytic activity towards glycerol electrooxidation is investigated by employing cyclic voltammetry CV and linear sweep voltammetry LSV. The morphology and composition of the various Ni Cu CF are investigated using X ray diffraction XRD and field emission scanning electron microscopy FE SEM together with various electrochemical measurements e.g., CV, chronoamperometry, LSV . The co deposition of Ni Cu shows a dendritic like structure with higher electrocatalytic activity towards glycerol electrooxidation compared to the monometallic counterparts. Interestingly, the best electrode NiCu CF Ni particles as the top layer prepared by sequential electrodeposition shows 1.6 fold higher glycerol oxidation activity, manifested in oxidation current, compared to Ni coated CF due to Ni particles covering the surface of dendritic copper uniformly. Thus, the surface concentration of Ni is increased and at the same time a synergistic effect occurs between Ni and Cu by the simple addition of Cu which reinforces the surface concentration of Ni from 3.4 10 amp; 8722;8 to 1.1 10 amp; 8722;7 mol cm amp; 8722;

Uses of Diagnostic Ultrasonography in the Diagnosis of Some Digestive Disorders in Cattle and Buffalo

The bovine sector represents an important part of the animal resources in Egypt, as it plays important role in supplying humans with a considerable part of their daily needs of animal-derived proteins via their milk and meat. However, such animal species can be exposed during their life to a wide range of digestive disorders, which affect animal performance and productivity. Ultrasonography plays an essential role in the accurate and rapid diagnosis of several diseases affecting cattle and buffaloes. In this review, we will highlight the role of ultrasonography in the diagnosis of digestive disorders in cattle and buffaloes. &nbsp

Shape Controlled Electroless Plating of Hetero Nanostructures AgCu and AgNi Decorated Ag Nanoplates on Carbon Fibers as Catalysts for the Oxygen Evolution Reaction

This study addresses the potential of combining multiple electroless plating reactions for homogeneous decoration of three dimensional carbon fibers CFs with shape controlled AgNi and AgCu bimetallic nanostructures. Morphology, crystal structure, and composition of the obtained bimetallic nanostructures were systemically examined by various spectroscopic and microscopic techniques including scanning electron microscopy, transmission electron microscopy, X ray diffraction, and X ray photoelectron spectroscopy. The electrocatalytic performance of the synthesized materials was investigated for the oxygen evolution reaction OER . AgCu and AgNi bimetallic surfaces showed superior activity and stability compared to pristine Ag, Ni, or Cu. These observed enhancements on the bimetallic nanostructures are attributed to the synergistic effect between the elements present. AgNi nanoplate decorated CFs exhibited the highest activity toward OER, which is attributed to the key role of Ag in stabilizing and increasing the number of amp; 946; NiOOH surface sites, which are the most relevant OER active Ni specie

Comparative Spectroscopic Study Revealing Why the CO2 Electroreduction Selectivity Switches from CO to HCOO at Cu Sn and Cu In Based Catalysts

To address the challenge of selectivity toward single products in Cu catalyzed electrochemical CO2 reduction, one strategy is to incorporate a second metal with the goal of tuning catalytic activity via synergy effects. In particular, catalysts based on Cu modified with post transition metals Sn or In are known to reduce CO2 selectively to either CO or HCOO depending on their composition. However, it remains unclear exactly which factors induce this switch in reaction pathways and whether these two related bimetal combinations follow similar general structure activity trends. To investigate these questions systematically, Cu In and Cu Sn bimetallic catalysts were synthesized across a range of composition ratios and studied in detail. Compositional and morphological control was achieved via a simple electrochemical synthesis approach. A combination of operando and quasi in situ spectroscopic techniques, including X ray photoelectron, X ray absorption, and Raman spectroscopy, was used to observe the dynamic behaviors of the catalysts surface structure, composition, speciation, and local environment during CO2 electrolysis. The two systems exhibited similar selectivity dependency on their surface composition. Cu rich catalysts produce mainly CO, while Cu poor catalysts were found to mainly produce HCOO . Despite these similarities, the speciation of Sn and In at the surface differed from each other and was found to be strongly dependent on the applied potential and the catalyst composition. For Cu rich compositions optimized for CO production Cu85In15 and Cu85Sn15 , indium was present predominantly in the reduced metallic form In0 , whereas tin mainly existed as an oxidized species Sn2 4 . Meanwhile, for the HCOO selective compositions Cu25In75 and Cu40Sn60 , the indium exclusively exhibited In0 regardless of the applied potential, while the tin was reduced to metallic Sn0 only at the most negative applied potential, which corresponds to the best HCOO selectivity. Furthermore, while Cu40Sn60 enhances HCOO selectivity by inhibiting H2 evolution, Cu25In75 improves the HCOO selectivity at the expense of CO production. Due to these differences, we contend that identical mechanisms cannot be used to explain the behavior of these two bimetallic systems Cu In and Cu Sn . Operando surface enhanced Raman spectroscopy measurements provide direct evidence of the local alkalization and its impact on the dynamic transformation of oxidized Cu surface species Cu2O CuO into a mixture of Cu OH 2 and basic Cu carbonates [Cux OH y CO3 y] rather than metallic Cu under CO2 electrolysis. This study provides unique insights into the origin of the switch in selectivity between CO and HCOO pathways at Cu bimetallic catalysts and the nature of surface active sites and key intermediates for both pathway

Electrocatalyst Derived from Waste Cu Sn Bronze for CO2 Conversion into CO

To sustainably exist within planetary boundaries, we must greatly curtail our extraction of fuels and materials from the Earth. This requires new technologies based on reuse and repurposing of material already available. Electrochemical conversion of CO2 into valuable chemicals and fuels is a promising alternative to deriving them from fossil fuels. But most metals used for electrocatalysis are either endangered or at serious risk of limitation to their future supply. Here, we demonstrate a combined strategy for repurposing of a waste industrial Cu Sn bronze as a catalyst material precursor and its application toward CO2 reuse. By a simple electrochemical transfer method, waste bronzes with composition Cu14Sn were anodically dissolved and cathodically redeposited under dynamic hydrogen bubble template conditions to yield mesoporous foams with Cu10Sn surface composition. The bimetal foam electrodes exhibited high CO2 electroreduction selectivity toward CO, achieving greater than 85 faradaic efficiency accompanied by a considerable suppression of the competing H2 evolution reaction. The Cu Sn foam electrodes showed good durability over several hours of continuous electrolysis without any significant change in the composition, morphology, and selectivity for CO as a target produc

Natalizumab plus interferon beta-1a for relapsing multiple sclerosis.

Item does not contain fulltextBACKGROUND: Interferon beta is used to modify the course of relapsing multiple sclerosis. Despite interferon beta therapy, many patients have relapses. Natalizumab, an alpha4 integrin antagonist, appeared to be safe and effective alone and when added to interferon beta-1a in preliminary studies. METHODS: We randomly assigned 1171 patients who, despite interferon beta-1a therapy, had had at least one relapse during the 12-month period before randomization to receive continued interferon beta-1a in combination with 300 mg of natalizumab (589 patients) or placebo (582 patients) intravenously every 4 weeks for up to 116 weeks. The primary end points were the rate of clinical relapse at 1 year and the cumulative probability of disability progression sustained for 12 weeks, as measured by the Expanded Disability Status Scale, at 2 years. RESULTS: Combination therapy resulted in a 24 percent reduction in the relative risk of sustained disability progression (hazard ratio, 0.76; 95 percent confidence interval, 0.61 to 0.96; P=0.02). Kaplan-Meier estimates of the cumulative probability of progression at two years were 23 percent with combination therapy and 29 percent with interferon beta-1a alone. Combination therapy was associated with a lower annualized rate of relapse over a two-year period than was interferon beta-1a alone (0.34 vs. 0.75, P<0.001) and with fewer new or enlarging lesions on T(2)-weighted magnetic resonance imaging (0.9 vs. 5.4, P<0.001). Adverse events associated with combination therapy were anxiety, pharyngitis, sinus congestion, and peripheral edema. Two cases of progressive multifocal leukoencephalopathy, one of which was fatal, were diagnosed in natalizumab-treated patients. CONCLUSIONS: Natalizumab added to interferon beta-1a was significantly more effective than interferon beta-1a alone in patients with relapsing multiple sclerosis. Additional research is needed to elucidate the benefits and risks of this combination treatment. (ClinicalTrials.gov number, NCT00030966.)