Platinum

About: Platinum is a research topic. Over the lifetime, 49675 publications have been published within this topic receiving 1150035 citations. The topic is also known as: Pt & element 78.

Solution-Based Evolution and Enhanced Methanol Oxidation Activity of Monodisperse Platinum-Copper Nanocubes**

Abstract: Shape-controlled catalysis: High-quality Pt-Cu nanocubes with an average size of about 8 nm (see picture, scale bar = 20 nm) were synthesized from a high-temperature organic solution system in the presence of various capping ligands. These cubic Pt-Cu nanocrystals terminated with {100} facets demonstrated a superior catalytic activity towards methanol oxidation compared to similar sized Pt-Cu and Pt nanospheres.

Platinum(0)-catalyzed diboration of alkynes

Abstract: Recently, much attention has been focused on the addition reactions of the metal-metal bonds to alkynes or alkenes as a simple method for the direct synthesis of polymetallic organic compounds. The additions of bimetallic reagents such as the silicon-metal2 and the tin-metal3 compounds to the C-C unsaturated bonds have been extensively studied; however, there are few reports concerning the metal-boron compounds. For instance, there are only two known addition reactions of the Si-B (silylboration) and the Sn-B compounds (stannylboration) to alkyne^.^ Perhaps prejudice due to the fact that the boron compounds have a relatively high bond energy has precluded investigation in this area. We have recently reported that the additions of catecholborane to alkenes and alkynes are catalyzed by the Pd(O), Rh(I), or Ni(0) c o m p l e x e ~ ~ ~ and that the thioboration of alkynes with 9-organothio-9-BBN derivatives is induced by using catalytic amounts of the Pd(0) complex.* As a part of this program on the catalytic addition reactions of boron compounds, we report here the first example of the syn-selective addition of tetraalkoxydiboron 1 to alkynes 2. The reaction was efficiently catalyzed by the platinum(0) complex (eq 1). Although the additions of diboron tetrahalides X2B-BX2 (X = C1, F) to alkenes and alkynes were already reported by Schlesinger in 1959,9 their ester or amide analogues are completely

An amperometric microsensor for the determination of H2S in aquatic environments

Abstract: A new amperometric microsensor for detection of dissolved H2S in aquatic environments was developed The design of the microsensor is based on the same principle as the Clark-type oxygen microsensor The sensor is equipped with a glass-coated platinum working electrode and a platinum guard electrode positioned in an outer glass casing (tip diameter 20−100 μm) Both working electrode and guard electrode were polarized at a fixed value in the range from +85 to + 150 mV with respect to a counter electrode The outer casing is sealed with a thin silicone membrane and filled with a buffered electrolyte solution containing ferricyanide (K3[Fe(CN)6]) as redox mediator Hydrogen sulfide penetrates the silicone membrane and is oxidized by K3[Fe(CN)6], resulting in the formation of elemental sulfur and ferrocyanide (K4[Fe(CN)6]) The latter is electrochemically reoxidized at the exposed end of the platinum working electrode, thereby creating a current that is directly proportional to the dissolved H2S concentration

Atomically dispersed iron hydroxide anchored on Pt for preferential oxidation of CO in H-2

Abstract: Proton-exchange-membrane fuel cells (PEMFCs) are attractive next-generation power sources for use in vehicles and other applications1, with development efforts focusing on improving the catalyst system of the fuel cell. One problem is catalyst poisoning by impurity gases such as carbon monoxide (CO), which typically comprises about one per cent of hydrogen fuel2-4. A possible solution is on-board hydrogen purification, which involves preferential oxidation of CO in hydrogen (PROX)3-7. However, this approach is challenging8-15 because the catalyst needs to be active and selective towards CO oxidation over a broad range of low temperatures so that CO is efficiently removed (to below 50 parts per million) during continuous PEMFC operation (at about 353 kelvin) and, in the case of automotive fuel cells, during frequent cold-start periods. Here we show that atomically dispersed iron hydroxide, selectively deposited on silica-supported platinum (Pt) nanoparticles, enables complete and 100 per cent selective CO removal through the PROX reaction over the broad temperature range of 198 to 380 kelvin. We find that the mass-specific activity of this system is about 30 times higher than that of more conventional catalysts consisting of Pt on iron oxide supports. In situ X-ray absorption fine-structure measurements reveal that most of the iron hydroxide exists as Fe1(OH)x clusters anchored on the Pt nanoparticles, with density functional theory calculations indicating that Fe1(OH)x-Pt single interfacial sites can readily react with CO and facilitate oxygen activation. These findings suggest that in addition to strategies that target oxide-supported precious-metal nanoparticles or isolated metal atoms, the deposition of isolated transition-metal complexes offers new ways of designing highly active metal catalysts.