Enhancement of surface self-diffusion of platinum atoms by adsorbed hydrogen

Morphology changes of Pt-foil catalyst induced by temperature-controlled ammonia oxidation near atmospheric pressure

“…The required presence of the feed mixture containing oxygen and ammonia suggests that adsorbates provide Pt atoms with the mobility or driving force necessary for facet formation. As demonstrated by Horch et al [29], hydrogen is a possible candidate that enhances the diffusion rate of Pt atoms on a Pt(1 1 0) surface up to 500 times at room temperature ( p H2 = 7 Â 10 À7 mbar) when monitored by STM, interpreted as lowering of the respective energy barrier. Moreover, also ammonia was reported to increase the surface mobility of step atoms on a Pt(4 4 3) surface in such a way that the straight step edges completely dissolved within 15 min at room temperature ( p NH3 = 10 À6 mbar) [30].…”

Size dependence of nanostructures: Impact of bond order deficiency

“…In addition to the large surface-to-volume ratios, the surface, interface, and quantum effects take on a significance that is normally inconsequential for bulk materials. Varieties of physical properties such as mechanical strength, plasticity [8], sintering and alloying ability [9], diffusivity [10], chemical reactivity [11,12], as well as the mode of crystal growth (self-assembly) have been found to be dependent upon particle size. Property tunability also includes thermodynamics (critical temperatures for phase transitions such as liquidation, evaporation, and heat transport), lattice dynamics (optical and acoustic modes of lattice vibration), optics (photoemission and absorption) [13e15], electronics (work function, energy-level positions, electronephonon coupling) [16,17], magnetic (magnetization tailoring or enhancement) and dielectric performance.…”

Energetics and Vibrational States for Hydrogen on Pt(111)

“…Our results convincingly demonstrate the need to go beyond the local harmonic oscillator picture to understand the dynamics of this system. Hydrogen on metal surfaces, and in particular on Pt(111), has received considerable experimental [1][2][3][4][5][6][7] and theoretical [8][9][10][11][12][13][14][15] attention. Together with Pd, Pt is the most important material for heterogeneous catalysis of hydrogenation reactions.…”