Henrik Svengren

Well‐Defined Palladium Nanoparticles Supported on Siliceous Mesocellular Foam as Heterogeneous Catalysts for the Oxidation of Water

Herein, we describe the use of Pd nanoparticles immobilized on an amino-functionalized siliceous mesocellular foam for the catalytic oxidation of H2O. The Pd nanocatalyst proved to be capable of mediating the four-electron oxidation of H2O to O2, both chemically and photochemically. The Pd nanocatalyst is easy to prepare and shows high chemical stability, low leaching, and recyclability. Together with its promising catalytic activity, these features make the Pd nanocatalyst of potential interest for future sustainable solar-fuel production.

Cobalt selenium oxohalides: catalysts for water oxidation.

Two new oxohalides Co4Se3O9Cl2 and Co3Se4O10Cl2 have been synthesized by solid state reactions. They crystallize in the orthorhombic space group Pnma and the monoclinic space group C2/m respectively. The crystal structure of the two compounds are made up of similar building blocks; Co4Se3O9Cl2 is made up of [CoO4Cl2], [CoO5Cl] and [SeO3] polyhedra and Co3Se4O10Cl2 is made up of [CoO4Cl2] and [SeO3] polyhedra. As several Co-containing compounds have proved to be good catalysts for water oxidation, the activities of the two new compounds were compared with the previously found oxohalide Co5Se4O12Cl2 in reference to CoO and CoCl2. The one electron oxidant Ru(bpy)3(3+) was used as oxidizing species in a phosphate buffer and it was found that the activities of the oxohalide species were in between CoO and CoCl2. The roles of Cl(-) and PO4(3-) ions are discussed.

An Oxofluoride Catalyst Comprised of Transition Metals and a Metalloid for Application in Water Oxidation

The application of the recently discovered oxofluoride solid solution (Cox Ni1-x )3 Sb4 O6 F6 as a catalyst for water oxidation is demonstrated. The phase exhibits a cubic arrangement of the active metal that forms oxo bridges to the metalloid with possible catalytic participation. The Co3 Sb4 O6 F6 compound proved to be capable of catalyzing 2H2 O→O2 +4H(+) +4e(-) at 0.33 V electrochemical and ≤0.39 V chemical overpotential with a TOF of 4.4⋅10(-3) , whereas Ni3 Sb4 O6 F6 needs a higher overpotential. Relatively large crystal cubes (0.3-0.5 mm) are easily synthesized and readily handled as they demonstrate both chemical resistance to wear after repeated in situ tests under experimental conditions, and have a mechanical hardness of 270 V0.1 using Vickers indentation. The combined properties of this compound offer a potential technical advantage for incorporation to a catalytic interface in future sustainable fuel production.

An Assessment of the Density of a Large Carnivore using a Non-Invasive Method Adapted for Pilot Studies

The recent increase in habitat fragmentation across our continents calls for concern with regard to the future survival of wildlife. In this respect corridors and stepping-stones are important. Targeting a wide-ranging top-trophic carnivore, the aim of this study was to estimate the density and abundance of leopards (Panthera pardus) in an area that might serve as a stepping-stone between other larger protected areas. We deliberately used a survey method designed to balance resource utilization and relevance of the results to fit the purpose of a pilot survey. The Sangare Ranch Conservancy is a newly established, privately owned park in Kenya. Using non-invasive techniques we identified 13 individual leopards composing of approximately 80% males. In addition, we found 28 leopard signs per 100 km walked, a predicted carrying capacity of around nine leopards/100 km2 and a leopard predation pressure on neighboring goat stock of 5.6%. We suggest that the conservancy plays an important role for leopard ecology and comprises a geographical and ecological stepping-stone between other protected wild habitats in the region. The study also suggests more efficient methods for future non-invasive studies.

Direct Synthesis of Two Inorganic Catalysts on Carbon Fibres for the Electrocatalytic Oxidation of Water

Two electrodes for anodic water oxidation made by direct synthesis of inorganic catalysts onto conductive carbon fibre sheets are evaluated. As catalysts two Co- and Sb-containing phases were tested, that is, Co3 Sb4 O6 F6 and the new compound CoSbO4 . The compounds express large differences in their morphology: CoSbO4 grows as thin needles whereas Co3 Sb4 O6 F6 grows as larger facetted crystals. Despite the smaller surface area the latter compound shows a better catalytic performance. When the compound Co3 Sb4 O6 F6 was used it gave a low increase of +0.028 mV h-1 at an overpotential of η=472 mV after 10 h and a stability of +0.48 mV h-1 at an overpotential of η=488 mV after 60 h. The leakages of Co and Sb were negligible and only <0.001 at % Co and approximately 0.02 at % Sb were detected in the electrolyte.