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Spectroscopic Detection of Hydrogen Atom Spillover from Au Nanoparticles Supported on TiO2: Use of Conduction Band Electrons

“…There is a small amount of experimental and theoretical information about the activation barrier of H 2 dissociation on Au surfaces. Kislyuk and Tretyakov reported an activation energy of 18 kcal/mol (0.78 eV) for thermal atomization of H 2 on gold wire at 950−1250 K. Hammer and Nørskov using density functional theory (DFT) calculations have shown that the dissociation of H 2 on Au is an activated process: for large molecule−surface distance, d , the interaction energy is repulsive with a high barrier of 1.1 eV (around d = 1.5 Å) for the H 2 → H + H reaction. Strømsnes et al calculated that dissociative chemisorption of molecular hydrogen on seven atom gold clusters has an activation barrier of 33 kcal/mol (1.43 eV).…”

Electrochemically induced oxygen spillover and diffusion on Pt(111): PEEM imaging and kinetic modelling

“…Again, we have to emphasize that the obtained diffusion coefficient is an average for a surface with an unknown number of surface steps. 111), FEM, 50 (h) Pt(100), FEM, 47 and (i) Pt(111), STM. 48 The different result of the previously published diffusion coefficient based on PEEM experiments (D 670 K = 9.2 Â 10 À4 cm 2 s À1 ) 12,13 is most likely due to different experimental conditions: a polycrystalline Pt film electrode on a YSZ(100) crystal 24 was investigated at a smaller applied potential (V WR = 0.2 V).…”

“…Fig. 7 Comparison of oxygen surface diffusion coefficients at higher (a) Polycrystalline Pt, TDS, 47 (b) Pt(111), V WR = 0.2 V, PEEM, 12,13 (c) this study, Fickian diffusion model, filled dots: x = 55 mm, empty dots: x = 27.5 mm, (d) this study, reaction-diffusion model, (e) Pt(100), y o 0.2, PEEM, 26 (f) Pt(100), 0.2 o y o 0.7, PEEM, 26 (g) Pt(111), FEM,50 (h) Pt(100), FEM,47 and (i) Pt(111), STM 48. …”