3D-nanoarchitectured Pd/Ni catalysts prepared by atomic layer deposition for the electrooxidation of formic acid

• Loïc Assaud,
• Evans Monyoncho,
• Kristina Pitzschel,
• Anis Allagui,
• Matthieu Petit,
• Margrit Hanbücken,
• Elena A. Baranova and
• Lionel Santinacci

Beilstein J. Nanotechnol. 2014, 5, 162–172, doi:10.3762/bjnano.5.16

• film uniformly. This could be due to a lower surface energy between the Pd and the annealed substrate. It is even possible to form a Pd/Ni alloy if the NiO top layer appears only when the sample is exposed to air. The two different growth mechanisms demonstrate the strong influence of the substrate on

Synthesis of embedded Au nanostructures by ion irradiation: influence of ion induced viscous flow and sputtering

• Udai B. Singh,
• D. C. Agarwal,
• S. A. Khan,
• S. Mohapatra,
• H. Amekura,
• D. P. Datta,
• Ajay Kumar,
• R. K. Choudhury,
• T. K. Chan,
• Thomas Osipowicz and
• D. K. Avasthi

Beilstein J. Nanotechnol. 2014, 5, 105–110, doi:10.3762/bjnano.5.10

• embedding of NPs result from the different surface energies, i.e., the surface energy of the particle and its substrate, and the particle–substrate interface energy. It is reported that surface energy of embedded NPs is less than the surface energy of both glass and NPs [23]. The ion bombardment provides

• burrowing effect during ion beam irradiation because the Au nanoparticles want to minimize their surface energy. In this way embedded Au NPs can be created by ion irradiation of Au thin films, which may be an alternative way of ion beam assisted synthesis of embedded NPs after optimizing the thickness of

Design criteria for stable Pt/C fuel cell catalysts

• Josef C. Meier,
• Carolina Galeano,
• Ioannis Katsounaros,
• Jonathon Witte,
• Hans J. Bongard,
• Angel A. Topalov,
• Claudio Baldizzone,
• Stefano Mezzavilla,
• Ferdi Schüth and
• Karl J. J. Mayrhofer

Beilstein J. Nanotechnol. 2014, 5, 44–67, doi:10.3762/bjnano.5.5

• the reduction with hydrogen that permeates the ionomer from the anode chamber of the cell [44][45][46]. Platinum dissolution is expected to be especially severe for smaller platinum particles, which have a higher surface energy and are thus considered to dissolve already at lower potentials than bulk

Synthesis of boron nitride nanotubes from unprocessed colemanite

• Saban Kalay,
• Zehra Yilmaz and
• Mustafa Çulha

Beilstein J. Nanotechnol. 2013, 4, 843–851, doi:10.3762/bjnano.4.95

• yet. According to the nucleation theory, the formation of a core depends on surface energy, supersaturation, vapor pressure, temperature and binding energy [23][24]. To synthesize unique, high yield and large scale BNNTs, the synthesis mechanism has to be clearly understood. At the moment, two

Dynamic nanoindentation by instrumented nanoindentation and force microscopy: a comparative review

• Sidney R. Cohen and
• Estelle Kalfon-Cohen

Beilstein J. Nanotechnol. 2013, 4, 815–833, doi:10.3762/bjnano.4.93

• the overall force behavior at the nanoscale. Several groups considered the effects of adhesion under various contact mechanics models in the 1970s [9][10][11][12][13]. These models analyze the changing contact shapes and stresses that occur when the surface energy and the adhesive forces in the

• surface energy, expressed as adhesion within the contact zone. It was followed by the Derjaguin–Muller–Toporov (DMT) model, which is applicable for stiffer samples and a lower but non-negligible surface energy, probed by a comparably sharp tip [11]. The DMT model accounts for forces outside the contact

• importance of surface effects such as friction and surface energy, dropping to the sub-optical regime made optical determination of the contact geometry impossible. This led to the need to determine the contact region size from force–displacement curves. Fundamental equations and their limitations The

Structural, optical and photocatalytic properties of flower-like ZnO nanostructures prepared by a facile wet chemical method

• Sini Kuriakose,
• Neha Bhardwaj,
• Jaspal Singh,
• Biswarup Satpati and
• Satyabrata Mohapatra

Beilstein J. Nanotechnol. 2013, 4, 763–770, doi:10.3762/bjnano.4.87

• (Figure 2d). Defects on the ZnO nanosheets act as nucleation sites for the growth of secondary nanosheets. The primary and secondary nanosheets self-assemble to minimize the surface energy, and this leads to the formation of three-dimensional flower-like ZnO structures [30][40]. Photocatalytic studies

Multiple regimes of operation in bimodal AFM: understanding the energy of cantilever eigenmodes

• Daniel Kiracofe,
• Arvind Raman and
• Dalia Yablon

Beilstein J. Nanotechnol. 2013, 4, 385–393, doi:10.3762/bjnano.4.45

• second excitation. In this work, we take Ω1 = ω1 and Ω2 = ω2 to simulate bimodal driving of the 1st and 2nd eigenmodes. The tip–sample interaction force Fts(d) is described by a modified DMT model that includes a term for surface energy hysteresis. In other words, the force when the tip is approaching

• obtain the value at 250 kHz) for polypropylene and polyethylene at 250 kHz, respectively. Both materials have a surface energy hysteresis term of 0.06 J/m2 (chosen to approximately match the average energy dissipation in AM-AFM experiments). The same first eigenmode amplitude is used for both simulations

• jumps and the second eigenmode contrast does not reverse. Calibrated cantilever parameters for the experiments. Simulation parameters. Hamaker constant and surface energy are tuned to match the experiment. All other values are measured or nominal values. Supporting Information The Supporting

Micro- and nanoscale electrical characterization of large-area graphene transferred to functional substrates

• Gabriele Fisichella,
• Salvatore Di Franco,
• Patrick Fiorenza,
• Raffaella Lo Nigro,
• Fabrizio Roccaforte,
• Cristina Tudisco,
• Guido G. Condorelli,
• Nicolò Piluso,
• Noemi Spartà,
• Stella Lo Verso,
• Corrado Accardi,
• Cristina Tringali,
• Sebastiano Ravesi and
• Filippo Giannazzo

Beilstein J. Nanotechnol. 2013, 4, 234–242, doi:10.3762/bjnano.4.24

• can influence the surface adhesion between graphene and the substrate, including the substrate roughness and the surface energy. Though a complete understanding of this issue has not yet been achieved, it can be argued that, due to the inherent hydrophobic character of graphene, the adhesion of large

Catalytic activity of nanostructured Au: Scale effects versus bimetallic/bifunctional effects in low-temperature CO oxidation on nanoporous Au

• Lu-Cun Wang,
• Yi Zhong,
• Haijun Jin,
• Daniel Widmann,
• Jörg Weissmüller and
• R. Jürgen Behm

Beilstein J. Nanotechnol. 2013, 4, 111–128, doi:10.3762/bjnano.4.13

• thermodynamic point of view, Ag prefers either to be on the surface or to form interfacial alloys with Au, while Au prefers to segregate at the core due to the lower surface energy of Ag compared to Au in the absence of adsorbates [56][58]. This may be modified by strongly adsorbing species. The number of

• , with 5.3, 5.7 and 5.4 atom % for the samples NPG(Cu)-1 to NPG(Cu)-3, respectively, although to a much lesser extent compared with the NPG(Ag) materials. This can be simply explained by the lower surface energy of Au compared to that of Cu [63]. 2 Catalytic activities 2.1 Catalytic activities in the

Ordered arrays of nanoporous gold nanoparticles

• Dong Wang,
• Ran Ji,
• Arne Albrecht and
• Peter Schaaf

Beilstein J. Nanotechnol. 2012, 3, 651–657, doi:10.3762/bjnano.3.74

• to fabricate nanoparticles [14][15]. The dewetting of metal films is driven by reducing the surface energy of the film and the interface energy between the film and the substrate, and occurs by diffusion even well below the melting temperature of the film [15]. In addition, alloy nanoparticles can be

• (900 °C) is required for the dewetting on a flat substrate to form particles. Excess local chemical potential can be introduced by the prepatterned structure according to the Gibbs–Thomson relation, Δμ = κ·γ·Ω, where Δμ is the local excess chemical potential, κ the local curvature, γ the surface energy

Mapping mechanical properties of organic thin films by force-modulation microscopy in aqueous media

• Jianming Zhang,
• Zehra Parlak,
• Carleen M. Bowers,
• Terrence Oas and
• Stefan Zauscher

Beilstein J. Nanotechnol. 2012, 3, 464–474, doi:10.3762/bjnano.3.53

• , which suggests that the thiol molecules are not close-packed, and have some disorder in their arrangement on the surface. The contrast in the lateral-force image shows a friction difference between the gold surface and the EG3 patterns that can be attributed to the surface-energy difference between the

Conducting composite materials from the biopolymer kappa-carrageenan and carbon nanotubes

• Ali Aldalbahi,
• Jin Chu,
• Peter Feng and
• Marc in het Panhuis

Beilstein J. Nanotechnol. 2012, 3, 415–427, doi:10.3762/bjnano.3.48

• their high surface energy and van der Waals interactions [3][5][6][7]. To overcome this issue, a diverse range of molecules have been used to aid the dispersion of CNTs in aqueous media, such as surfactants, polymers and biopolymers [8][9][10][11][12][13][14][15][16]. Well known examples of surfactants

Reduced electron recombination of dye-sensitized solar cells based on TiO₂ spheres consisting of ultrathin nanosheets with [001] facet exposed

• Hongxia Wang,
• Meinan Liu,
• Cheng Yan and
• John Bell

Beilstein J. Nanotechnol. 2012, 3, 378–387, doi:10.3762/bjnano.3.44

• crystal facets [4]. It has been reported that the average surface energies of the different facets of anatase TiO2 lie in the order of [001] (0.90 J/m2) > [100] (0.53 J/m2) > [101] (0.44 J/m2) [5]. Apparently, the lowest surface energy of the [101] facet is the most stable surface of the TiO2 material

• . However, with the progress in synthesis techniques, other active facets of TiO2 crystals, such as [001], which is normally unstable due to a higher surface energy, can now be made [6]. In practice, TiO2 material with a large percentage of [001] high-energy surface has shown superior performance in

• nanosheets to realize a minimum surface energy. Some spheres have pits on the surface, which may be due to the insufficient reaction duration. The measurement of the N2 adsorption/desorption isotherms of the TiO2 powder shows that the specific surface area of the TiO2 spheres is 82 m2/g, which is slightly

Models of the interaction of metal tips with insulating surfaces

• Thomas Trevethan,
• Matthew Watkins and
• Alexander L. Shluger

Beilstein J. Nanotechnol. 2012, 3, 329–335, doi:10.3762/bjnano.3.37

• ) Energy as a function of cluster Cr tip height above the NaCl(001) surface. (b) Energy as a function of tip height above the MgO(001) surface. Energy as a function of tip height for the W tip interacting with the NaCl(001) surface. Constant-frequency-shift image (Δf = −60 Hz) of the NaCl surface imaged

Dipole-driven self-organization of zwitterionic molecules on alkali halide surfaces

• Laurent Nony,
• Franck Bocquet,
• Franck Para,
• Frédéric Chérioux,
• Eric Duverger,
• Frank Palmino,
• Vincent Luzet and
• Christian Loppacher

Beilstein J. Nanotechnol. 2012, 3, 285–293, doi:10.3762/bjnano.3.32

• step edges decorated with MSPS molecules that run along the <110> direction. These polar steps most probably minimize the surface energy as they counterbalance the molecular dipole by presenting oppositely charged ions on the rearranged step edge. Keywords: alkali halide surface; noncontact atomic

Electron-beam patterned self-assembled monolayers as templates for Cu electrodeposition and lift-off

• Zhe She,
• Andrea DiFalco,
• Georg Hähner and
• Manfred Buck

Beilstein J. Nanotechnol. 2012, 3, 101–113, doi:10.3762/bjnano.3.11

• e-beam lithography (2). Acting as a negative resist, electrochemical metal deposition (3) selectively occurs only in the nonirradiated areas. The low surface energy of the CH3 terminated SAM enables the transfer of the metal pattern to an insulating substrate (4,5) and reuse of the master pattern (6

Surface functionalization of aluminosilicate nanotubes with organic molecules

• Wei Ma,
• Weng On Yah,
• Hideyuki Otsuka and
• Atsushi Takahara

Beilstein J. Nanotechnol. 2012, 3, 82–100, doi:10.3762/bjnano.3.10

• adsorption and assembly of organic molecules on the imogolite surface is expected to produce interesting results. Imogolite may act as a one-dimensional scaffold for functional molecules. Moreover, the surface energy of imogolite nanotubes can be lowered by the organic layer, and this can greatly improve the

Octadecyltrichlorosilane (OTS)-coated ionic liquid drops: Micro-reactors for homogenous catalytic reactions at designated interfaces

• Xiaoning Zhang and
• Yuguang Cai

Beilstein J. Nanotechnol. 2012, 3, 33–39, doi:10.3762/bjnano.3.4

• methyl-terminated, low energy, lyophobic surface. Based on the wetting-driven assembly approach [10], liquid can be assembled on the chemical patterns due to the contrast in surface energy [11][12]. Figure 1a shows a representative OTSpd disc array. Figure 1b shows the same region after a liquid [Bmim]Cl

• drop rolled over the OTSpd discs. By comparing Figure 1a with Figure 1b, we found that the IL micro-drops were selectively deposited on the high-surface energy OTSpd chemical patterns. Figure 1c is the optical image of the IL drop arrays assembled on OTSpd patterns. The background is the OTS film. Each

Size-dependent phase diagrams of metallic alloys: A Monte Carlo simulation study on order–disorder transitions in Pt–Rh nanoparticles

• Johan Pohl,
• Christian Stahl and
• Karsten Albe

Beilstein J. Nanotechnol. 2012, 3, 1–11, doi:10.3762/bjnano.3.1

• equilibrium configuration of binary-alloy particles. It features full control over the mixing properties and surface-energy differences of the pure elements, which is the driving force for surface segregation in our model. The dependency of the phase diagram on particle size is examined on the basis of three

• volume solubility. When the platinum concentration is increased upward from zero, platinum atoms tend to form ordered domains at the (100) facets first (Figure 4, particle 1), because the difference in surface energy is larger for the (100) surface as compared to the (111) surface. We find some

• atoms, which is due to the surface energy of platinum being lower than that of rhodium. In reality, the size mismatch of platinum and rhodium may act as a another driving force for surface segregation. Size mismatch, however, is not accessible within a rigid lattice model. Above 46 atom % total platinum

Self-assembled monolayers and titanium dioxide: From surface patterning to potential applications

• Yaron Paz

Beilstein J. Nanotechnol. 2011, 2, 845–861, doi:10.3762/bjnano.2.94

• . Mixed SAMs with different ratios of –OH- and –CH3-terminated groups were used to control the surface energy and, as a result, to affect the growth of TiO2 by ALD from titanium isopropoxide and water [47]. Here, two-dimensional growth was observed on SAM-coated substrates with high surface energy

• , whereas a three-dimensional growth mode was found on SAM-coated substrates with low surface energy. The high affinity between OH groups and the titania precursor was later utilized for the growth of patterned domains of titania on patterned OH-terminated alkanethiolate monolayers on gold [48]. SAMs as a

Approaches to nanostructure control and functionalizations of polymer@silica hybrid nanograss generated by biomimetic silica mineralization on a self-assembled polyamine layer

• Jian-Jun Yuan and
• Ren-Hua Jin

Beilstein J. Nanotechnol. 2011, 2, 760–773, doi:10.3762/bjnano.2.84

• –superhydrophilic) by surface hydrophobic treatment and UV irradiation. The anatase titania component in the nanograss film acts as a highly efficient photocatalyst for the decomposition of the low-surface-energy organic components attached to the nanosurface. The ease with which the nanostructure can be controlled

• @titania composite nanograss surface was superhydrophilic (with θ = 0°) due to the high roughness and surface energy. After treatment with decyltrimethoxysilane (DecTMS) [46], the surface changed to become superhydrophobic with a water contact angle of about 179.8°. The water contact angles decreased to

• water contact angle could be attributed to the degradation of the low-surface-energy alkyl group due to the photocatalytic activity of anatase titania [47]. This was further confirmed by a simple control experiment. A superhydrophobic silica nanograss surface was produced by a similar DecTMS treatment

Lifetime analysis of individual-atom contacts and crossover to geometric-shell structures in unstrained silver nanowires

• Christian Obermair,
• Holger Kuhn and
• Thomas Schimmel

Beilstein J. Nanotechnol. 2011, 2, 740–745, doi:10.3762/bjnano.2.81

• contacting atoms by analogy with the “magic” configurations in metal cluster. In geometric shells the free energy is lowered by the change of surface energy when completing a layer of atoms on the nanowire facets, which is also known from cluster physics [20][21]. Both the electronic- and the geometric-shell

• oscillations of the free energy of the electron system of the contact, the amplitude of the local energy minima decreasing as 1/R due to shell filling [33]. On the other hand there is an oscillation in the surface energy due to the filling of geometric shells, for which the amplitude is roughly constant in

Generation and agglomeration behaviour of size-selected sub-nm iron clusters as catalysts for the growth of carbon nanotubes

• Ravi Joshi,
• Benjamin Waldschmidt,
• Jörg Engstler,
• Rolf Schäfer and
• Jörg J. Schneider

Beilstein J. Nanotechnol. 2011, 2, 734–739, doi:10.3762/bjnano.2.80

• temperatures above that particular temperature [14]. The size of the agglomerated clusters can be estimated on a thermodynamic basis [15], however, this does not include the influence of the cluster–substrate surface interaction on the surface energy of iron, which may also affect the cluster size

• . Nevertheless with the volume of the unit cell of 23.5 Å3 and the surface energy of 2.4 J/m2 for α-iron [16], a mean diameter of 3.0 nm with a standard deviation of 1.7 nm was obtained for a substrate temperature of 750 °C, which is in good agreement with the nanoparticle diameter as observed experimentally by

• size due to further agglomeration processes. During CNT growth, adsorbed hydrocarbons, hydrogen gas and water are present in a significant excess on the iron cluster surface, and thus these “surfactants” will certainly modify the surface energy of the catalyst clusters [23], and may have an additional

Formation of SiC nanoparticles in an atmospheric microwave plasma

• Martin Vennekamp,
• Ingolf Bauer,
• Matthias Groh,
• Evgeni Sperling,
• Susanne Ueberlein,
• Maksym Myndyk,
• Gerrit Mäder and
• Stefan Kaskel

Beilstein J. Nanotechnol. 2011, 2, 665–673, doi:10.3762/bjnano.2.71

• the free surface energy, vm as the molar volume, R as the gas constant and T as the absolute temperature. Solving the equilibrium equation for the excess surface energy of a small particle on the one hand, and the heat of condensation on the other hand, gives an expression for the minimum diameter of

• give an estimation of the critical diameter, the values in Equation 1 can be approximated as follows: The typical gas temperature for an atmospheric gas plasma is about 2000 K [23], the vapour pressure of SiC at this temperature is in the order of p∞ ≈ 0.2 Pa [24], the surface energy of SiC is σ ≈ 2000

Surface induced self-organization of comb-like macromolecules

• Konstantin I. Popov,
• Vladimir V. Palyulin,
• Martin Möller,
• Alexei R. Khokhlov and
• Igor I. Potemkin

Beilstein J. Nanotechnol. 2011, 2, 569–584, doi:10.3762/bjnano.2.61

• , but still larger than that for the isolated molecules. One possible explanation is the idea of “memory” of the intermediate conformation in the collapsed state. Another explanation takes into account the balance between the surface energy of 3D aggregate and the stretching free energy of combs in the

• stretching of the B chains. Both direct and inverse toruslike structures disappear with the decrease of SB at fixed values of γBa and γAa. This behavior is also related to the energy of the inner surface of the torus: Decreasing SB thickens the torus and increases the surface energy. The particular slope of