Volcano plots in hydrogen electrocatalysis – uses and abuses

• Paola Quaino,
• Fernanda Juarez,
• Elizabeth Santos and
• Wolfgang Schmickler

Beilstein J. Nanotechnol. 2014, 5, 846–854, doi:10.3762/bjnano.5.96

• principle. At polycrystalline metals there are even more sites and therefore more options. The relation between the two species is not simple, since the energy of the weakly adsorbed hydrogen depends on the coverage with the upd species. The best investigated case is Pt(111) in acid solutions, where the

• in detail in a a recent communication [25], where we have also calculated the isotherms for both species of adsorbed hydrogen on Pt(111). In any case, the interaction between the two species makes it quite difficult to calculate the adsorption free energy of the true intermediate state by DFT. In the

• above, only Pt(111) and rhenium in acid solutions actually follow this path. Sheng et al. [34] have proposed a volcano plot for alkaline solutions. All of these plots lose their volcano shapes, once the oxide-covered metals are deleted. Besides hydrogen adsorption energies, correlations have been

Adsorption and oxidation of formaldehyde on a polycrystalline Pt film electrode: An in situ IR spectroscopy search for adsorbed reaction intermediates

• Zenonas Jusys and
• R. Jürgen Behm

Beilstein J. Nanotechnol. 2014, 5, 747–759, doi:10.3762/bjnano.5.87

• /negative band) were reported previously for formaldehyde oxidation over a Pt(111) electrode [6]. Those authors tentatively assigned them to the symmetric deformation (scissoring) mode of a –CH2– (or –O–CH2) group for the former and to the C–O stretching mode of a –COH group for the latter band in a

• intermediates in density functional theory based studies of the interaction of methanol with a Pt(111) surface [50]. The importance of water in the initial steps of dehydrogenation of methanol over Pt(111) via polarization of the hydroxyl due to hydrogen bond formation with a neighboring water molecule was

• surfaces were used to approximate the potential-dependent methanol dehydrogenation pathways over different low index Pt electrode surfaces [49]. These calculations revealed pronounced structural effects, in agreement with experimental findings. For Pt(111), they suggested the coexistence of two pathways

Shape-selected nanocrystals for in situ spectro-electrochemistry studies on structurally well defined surfaces under controlled electrolyte transport: A combined in situ ATR-FTIR/online DEMS investigation of CO electrooxidation on Pt

• Sylvain Brimaud,
• Zenonas Jusys and
• R. Jürgen Behm

Beilstein J. Nanotechnol. 2014, 5, 735–746, doi:10.3762/bjnano.5.86

• species which differ drastically from those of a polycrystalline Pt film and which are characteristic for a Pt(111) surface with a well ordered surface. In the present paper we will further explore the potential of this approach, extending this to nanoparticles with different shapes/facet orientations and

• of the different batches of nanocrystals (see Table 2). Including this, the measured values agree well with the trend expected from the Epztc values of the low-index Pt single crystal electrodes (0.15, 0.38 and 0.32 V for Pt(110), Pt(100) and Pt(111) in 0.5 M H2SO4, respectively [27]. Similar to the

• )-NC than on the (111)-NC sample agrees well with trends expected from CO adsorption on Pt(100) and Pt(111) surfaces [8][35][36]. Furthermore, we find a slightly smaller difference in wave numbers (Δ) between the two binding modes of COad for (100)-NC than for (111)-NC. Also, the relative fraction of

Dye-sensitized Pt@TiO₂ core–shell nanostructures for the efficient photocatalytic generation of hydrogen

• Jun Fang,
• Lisha Yin,
• Shaowen Cao,
• Yusen Liao and
• Can Xue

Beilstein J. Nanotechnol. 2014, 5, 360–364, doi:10.3762/bjnano.5.41

• . Due to the low Pt loading, we could only observe a weak diffraction peak at 40o corresponding to the Pt (111) lattice spacing, which could indicate successful loading of metallic Pt nanoparticles onto TiO2 particles. The molar ratio of Pt to Ti was estimated to be about 6.7% according to EDX analysis

Change of the work function of platinum electrodes induced by halide adsorption

• Florian Gossenberger,
• Tanglaw Roman,
• Katrin Forster-Tonigold and
• Axel Groß

Beilstein J. Nanotechnol. 2014, 5, 152–161, doi:10.3762/bjnano.5.15

• , bromine and iodine on Pt(111) in order to check whether the findings for halogen adsorption on Cu(111) are also valid for the technologically important electrode material platinum. It has already been observed experimentally [18][19][20] as well as theoretically [11][13][17] that the adsorption of

• chlorine, bromine and iodine on Pt(111) leads to an unexpected decrease of the work function. Based on calculations for several adsorbates on tungsten surfaces, Leung, Kao and Su pointed out that it is possible to relate the electronegativity scale to the direction of the charge transfer but not

• depletion far from the surface, and in combination with an electron buildup in the area around the adsorbed ion, to a decrease of the work function. In this paper we present a detailed study of the halogen-induced change of the work function on Pt(111) as a function of the halogen coverage, which has still

Some reflections on the understanding of the oxygen reduction reaction at Pt(111)

• Ana M. Gómez-Marín,
• Ruben Rizo and
• Juan M. Feliu

Beilstein J. Nanotechnol. 2013, 4, 956–967, doi:10.3762/bjnano.4.108

• fundamental knowledge about its reaction mechanism is still lacking. In this paper, a global and critical view on the most important experimental and theoretical results regarding the ORR on Pt(111) and its vicinal surfaces, in both acidic and alkaline media, is taken. Phenomena such as the ORR surface

• electrocatalysts for fuel-cell cathodes is only possible through a cooperative approach between theory and experiments. Keywords: hydrogen peroxide oxidation; hydrogen peroxide reduction; oxygen reduction; Pt(111); stepped surfaces; Introduction Nowadays, the oxygen reduction reaction (ORR) is arguably one of

• presentation a critical view on the main recent experimental and theoretical findings about the ORR on Pt(111) and its vicinal stepped surfaces, in both acidic and alkaline media, is taken. The central idea is to find agreement and disagreement points that could serve to improve the current knowledge about the

Probing three-dimensional surface force fields with atomic resolution: Measurement strategies, limitations, and artifact reduction

• Mehmet Z. Baykara,
• Omur E. Dagdeviren,
• Todd C. Schwendemann,
• Harry Mönig,
• Eric I. Altman and
• Udo D. Schwarz

Beilstein J. Nanotechnol. 2012, 3, 637–650, doi:10.3762/bjnano.3.73

• normal force Fn is then calculated by taking the derivative of the total interaction potential in the vertical direction. The model tip apices used in the study are constructed from six close-packed atoms arranged in a three-layer planar configuration with the structural characteristics of a single Pt

• (111) plane (Figure 4a). The desired asymmetry in the tip-apex structure is obtained by rotating the model structures by an angle θ around the front-most atom (Figure 4b and Figure 4c). Even though we focus solely on this particular type of tip for the present discussion, we have calculated all cases

Transmission eigenvalue distributions in highly conductive molecular junctions

• Justin P. Bergfield,
• Joshua D. Barr and
• Charles A. Stafford

Beilstein J. Nanotechnol. 2012, 3, 40–51, doi:10.3762/bjnano.3.5

• function of the Pt(111) surface (−5.93 eV [24]) is shown for reference. Calculated van der Waals contribution to the binding energy of benzene adsorbed on a Pt(111) surface as a function of distance. Here the plane of the molecule is oriented parallel to the Pt surface. A phenomenological short-range

Femtosecond time-resolved photodissociation dynamics of methyl halide molecules on ultrathin gold films

• Mihai E. Vaida,
• Robert Tchitnga and
• Thorsten M. Bernhardt

Beilstein J. Nanotechnol. 2011, 2, 618–627, doi:10.3762/bjnano.2.65

• . However, neither photodissociation products nor the parent molecule were detected, independent on the pump–probe delay time. Similar results were reported by White and coworkers for methyl iodide adsorbed on Pt(111) [28][29][30][31]. In their work, methyl iodide molecules that were adsorbed on the metal

• surface were exposed to the full spectrum of an Hg arc lamp. The photodissociation and the desorption of the molecules from the surface was subsequently monitored by means of X-ray photoemission spectroscopy. White and coworkers reported that only 10% of the first CH3I layer adsorbed on the Pt(111

• ) substrate dissociated when the sample was irradiated for 120 min with a 100 W Hg arc lamp [29]. In contrast, a facile cleavage of the second layer was observed. According to vibrational spectroscopy investigations, the methyl iodide molecules adsorb on a Pt(111) surface with the halogen atom bound to the

Nanoscaled alloy formation from self-assembled elemental Co nanoparticles on top of Pt films

• Luyang Han,
• Ulf Wiedwald,
• Johannes Biskupek,
• Kai Fauth,
• Ute Kaiser and
• Paul Ziemann

Beilstein J. Nanotechnol. 2011, 2, 473–485, doi:10.3762/bjnano.2.51

• Physik IV, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany 10.3762/bjnano.2.51 Abstract The thermally activated formation of nanoscale CoPt alloys was investigated, after deposition of self-assembled Co nanoparticles on textured Pt(111) and epitaxial Pt(100) films on MgO(100) and SrTiO3(100

• under a H2 atmosphere, and the resulting variations of their structure, morphology and magnetic properties were characterized. We observed pronounced differences in the diffusion and alloying of Co nanoparticles on Pt films with different orientations and microstructures. On textured Pt(111) films

• resulting local alloy. In this paper we report the experimental details and results for the specific case of Co NPs on top of Pt(111)/MgO(100) and Pt(100)/SrTiO3(100). (For the sake of clarity and brevity, SrTiO3(100) is renamed STO(100) in the following). Pt films on MgO(100) and STO(100) Due to the

Preparation and characterization of supported magnetic nanoparticles prepared by reverse micelles

• Ulf Wiedwald,
• Luyang Han,
• Johannes Biskupek,
• Ute Kaiser and
• Paul Ziemann

Beilstein J. Nanotechnol. 2010, 1, 24–47, doi:10.3762/bjnano.1.5

• , in case of Pt, (111)-textured thin films (50 nm) were used which were obtained by pulsed laser deposition (PLD) at ambient temperature on MgO(001) or (100)-oriented films (80 nm) epitaxially grown by PLD on (001) strontium titanate (SrTiO3) crystals at 400 °C. In all cases, no special pre-treatment

• nanoparticles on Pt films The approach of compensating diamagnetic substrate signals by paramagnetic films is demonstrated by paramagnetic Pt(111) films on top of MgO(001) substrates. Pt films were deposited under UHV conditions at ambient temperature by pulsed laser deposition (PLD). For this purpose a 193 nm