Platinum bonds respond to surface structures up to 10 nanometres away
Researchers at the Max Planck Institute for Multidisciplinary Sciences and the Center for Quantum Nanoscience found that a molecule’s bond to platinum can be affected by a surface step up to about 10 nanometres away. The Science study measured ammonia, carbon monoxide and nitric oxide, finding that the distance of the effect varied by molecule and that adsorption energies changed by up to 0.2 electron volts.
Bottom line — The findings suggest models of platinum catalysts must account for surface structure beyond the atoms next to a molecule.
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The researchers measured binding energies by tracking how quickly molecules left platinum surfaces with regularly spaced atomic steps.
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The effect extended about 7 nanometres for ammonia, 6 for carbon monoxide and 4 for nitric oxide, according to the research team.
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A model developed by the team links the different responses to how each molecule couples with electronic states in the metal.
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The researchers found the long-range effect was much weaker on palladium than on platinum.
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The Max Planck Institute said nanoscale platinum particles can be only a few nanometres across, comparable to the distances over which bond strength remained sensitive to surface structure.