Thermal annealing, platinum

Galvanic displacement method is also often used for synthesizing catalysts. By this method, low Pt-content electrocatalysts can be obtained. For example, a carbon-supported core—shell structured electrocatalyst with bimetallic IrNi as the core and platinum monolayer as the shell has been successfully synthesized using this method. In this synthesis, IrNi core supported on carbon was first synthesized by a chemical reduction and thermal annealing method and a Ni core and Ir shell structure could be formed finally. The other advantage of this method is that the Ni can be completely encased by Ir shell, which will protect Ni dissolve in acid medium. Secondly, IrNi PtML/C core—shell electrocatalyst was prepared by depositing a Pt monolayer on the IrNi substrate by galvanic displacement of a Cu monolayer formed by under potential deposition (UPD). 

Miniature bead thermistors, which are particularly valuable as temperature sensors, can be made by arranging two sets of fine platinum wires at right angles with a separation of a fraction of a millimetre between the sets. The intersections of the wires are then enclosed by small beads of paste containing the thermistor material in powder form. The beads are dried out and sintered in the same way as bulk units or fused individually with a laser beam or an oxidizing flame and annealed. The beads are then separated with two platinum lead wires which can be attached to a probe. Their small mass enables them to reach a rapid thermal equilibrium with their surroundings. 

CoPt3 nanoparticles earn interest as representatives of alloy-hke species. Furthermore, they are less sensitive towards oxygen and so are somewhat easier to be prepared and to be handled. They become available by simultaneous reduction of platinum acetylacetonate and thermal decomposition of Co2(CO)g. As stabilizing agents, adamantanecarboxyhc acid and hexadecylamine (HAD) are used. Practically, the hot injection technique is applied. The recipient vessel contains the platinum salt, dissolved in 1,2-hexadecanediol, and the stabilizers, whereas Co2(CO)g in 1,2-dichlorobenzene is injected into the hot stock solution. In order to obtain well crystallized nanoparticles, annealing of the reaction mixture at 275 285 °C for about an hour is necessary. The crystalhnity can be checked by TEM andXRD. Figure 7 shows... 

Carborane (C2B10H12) and decaborane (B10H14) adsorb molecularly on the Pt(lll) surface at 85 K. Both molecules undergo thermal dissociation as the surface is annealed to higher temperatures, as indicated by RAIR spectra and by TPD. These results show that the platinum surface catalyses the low temperature release of hydrogen from both molecules. In both cases, boron remains on the surface up to temperatures as high as 700 K. 

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