The Open Gate Phenomenon
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The mechanism is not based on electrochemistry nor is it related to Strong Metal Support Interactions (SMSI) observed in catalysis although the materials are similar to those involved in SMSI studies.  The key difference is that for the Open Gate Phenomenon, the metal particles are grown from the polycrystalline reduced titania substrate, not deposited onto the support as related to SMSI.  The two phenomenon are based on completely different material preparations and therefore their chemistry/materials composition are not the same.  A paper titled, The Open Gate Phenomenon- An Overview, provides a more in-depth discussion of the original studies that identified the Open Gate Phenomenon, information about the solid state mechanism itself, and the material preparations required to produce it.

 

Material Prepartion Requirements-  The original research involved inserting rhodium (approximately one percent) into the TiO2 lattice using a preparation technique for alkaline earth titanates with a resin intermediate (Pechini process) as described by Maggio Pechini in  Patent 3,330,697 (July 11, 1967).  The resin intermediate is then subjected to elevated temperatures at approximately 1000 C first in an oxidizing environment (O2) and followed by a reducing environment (H2). Varying material preparation proved that temperatures in excess of approximately 800 C are required, however less harshly reducing conditions such as 1% H2 in argon are also effective.  It was also found that the initial material preparation is not limited to the resin intermediate preparation (Pechini process).  Although not as effective as the Pechini process preparation, an incipient wetness impregnation (simple "salt evaporation") preparation followed by the high temperature oxidation and reduction also produces the mechanism.

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