Next Issue
Previous Issue

Table of Contents

Surfaces, Volume 2, Issue 1 (March 2019)

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
Cover Story (view full-size image) Energy transfer between excited electrons and adsorbate vibrational modes is behind surface [...] Read more.
View options order results:
result details:
Displaying articles 1-16
Export citation of selected articles as:
Open AccessArticle
Cyclic Voltammetry Characterization of Au, Pd, and AuPd Nanoparticles Supported on Different Carbon Nanofibers
Surfaces 2019, 2(1), 205-215; https://doi.org/10.3390/surfaces2010016
Received: 18 January 2019 / Revised: 28 February 2019 / Accepted: 13 March 2019 / Published: 19 March 2019
Viewed by 272 | PDF Full-text (3024 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Three types of carbon nanofibers (pyrolytically stripped carbon nanofibers (PS), low-temperature heat treated carbon nanofibers (LHT), and high-temperature heat treated carbon nanofibers (HHT)) with different graphitization degrees and surface chemistry have been used as support for Au, Pd, or bimetallic AuPd alloy nanoparticles [...] Read more.
Three types of carbon nanofibers (pyrolytically stripped carbon nanofibers (PS), low-temperature heat treated carbon nanofibers (LHT), and high-temperature heat treated carbon nanofibers (HHT)) with different graphitization degrees and surface chemistry have been used as support for Au, Pd, or bimetallic AuPd alloy nanoparticles (NPs). The carbon supports have been characterized using Raman, X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV). Moreover, the morphology of the metal nanoparticles was investigated using transmission electron microscopy (TEM) and CV. The different properties of the carbon-based supports (particularly the graphitization degree) yield different electrochemical behaviors, in terms of potential window widths and electrocatalytic effects. Comparing the electrochemical behavior of monometallic Au and Pd and bimetallic AuPd, it is possible to observe the interaction of the two metals when alloyed. Moreover, we demonstrate that carbon surface has a strong effect on the electrochemical stability of AuPd nanoparticles. By tuning the Au-Pd nanoparticles’ morphology and modulating the surface chemistry of the carbon support, it is possible to obtain materials characterized by novel electrochemical properties. This aspect makes them good candidates to be conveniently applied in different fields. Full article
(This article belongs to the Special Issue Electrochemical Surface Science: Basics and Applications)
Figures

Figure 1

Open AccessArticle
“Click” Chemistry on Gold Electrodes Modified with Reduced Graphene Oxide by Electrophoretic Deposition
Surfaces 2019, 2(1), 193-204; https://doi.org/10.3390/surfaces2010015
Received: 22 January 2019 / Revised: 6 March 2019 / Accepted: 8 March 2019 / Published: 18 March 2019
Viewed by 255 | PDF Full-text (3516 KB) | HTML Full-text | XML Full-text
Abstract
The coating of electrical interfaces with reduced graphene oxide (rGO) films and their subsequent chemical modification are essential steps in the fabrication of graphene-based sensing platforms. In this work, electrophoretic deposition (EPD) of graphene oxide at 2.5 V for 300 s followed by [...] Read more.
The coating of electrical interfaces with reduced graphene oxide (rGO) films and their subsequent chemical modification are essential steps in the fabrication of graphene-based sensing platforms. In this work, electrophoretic deposition (EPD) of graphene oxide at 2.5 V for 300 s followed by vapor treatment were employed to coat gold electrodes uniformly with rGO. These interfaces showed excellent electron transfer characteristics for redox mediators such as ferrocene methanol and potassium ferrocyanide. Functional groups were integrated onto the Au/rGO electrodes by the electro-reduction of an aryldiazonium salt, 4-((triisopropylsilyl)ethylenyl)benzenediazonium tetrafluoroborate (TIPS-Eth-ArN) in our case. Chemical deprotection of the triisopropylsilyl function resulted in propargyl-terminated Au/rGO electrodes to which azidomethylferrocene was chemically linked using the Cu(I) catalyzed “click” chemistry. Full article
(This article belongs to the Special Issue Electrochemical Surface Science: Basics and Applications)
Figures

Graphical abstract

Open AccessArticle
Effects of the Interfacial Structure on the Methanol Oxidation on Platinum Single Crystal Electrodes
Surfaces 2019, 2(1), 177-192; https://doi.org/10.3390/surfaces2010014
Received: 11 February 2019 / Revised: 27 February 2019 / Accepted: 1 March 2019 / Published: 12 March 2019
Viewed by 250 | PDF Full-text (2060 KB) | HTML Full-text | XML Full-text
Abstract
Methanol oxidation has been studied on low index platinum single crystal electrodes using methanol solutions with different pH (1–5) in the absence of specific adsorption. The goal is to determine the role of the interfacial structure in the reaction. The comparison between the [...] Read more.
Methanol oxidation has been studied on low index platinum single crystal electrodes using methanol solutions with different pH (1–5) in the absence of specific adsorption. The goal is to determine the role of the interfacial structure in the reaction. The comparison between the voltammetric profiles obtained in the presence and absence of methanol indicates that methanol oxidation is only taking place when the surface is partially covered by adsorbed OH. Thus, on the Pt(111) electrode, the onset for the direct oxidation of methanol and the adsorption of OH coincide. In this case, the adsorbed OH species are not a mere spectator, because the obtained results for the reaction order for methanol and the proton concentrations indicate that OH adsorbed species are involved in the reaction mechanism. On the other hand, the dehydrogenation step to yield adsorbed CO on the Pt(100) surface coincides with the onset of OH adsorption on this electrode. It is proposed that adsorbed OH collaborates in the dehydrogenation step during methanol oxidation, facilitating either the adsorption of the methanol in the right configuration or the cleavage of the C—H bond. Full article
(This article belongs to the Special Issue Electrochemical Surface Science: Basics and Applications)
Figures

Graphical abstract

Open AccessArticle
Strategies to Hierarchical Porosity in Carbon Nanofiber Webs for Electrochemical Applications
Surfaces 2019, 2(1), 159-176; https://doi.org/10.3390/surfaces2010013
Received: 4 February 2019 / Revised: 22 February 2019 / Accepted: 25 February 2019 / Published: 5 March 2019
Viewed by 317 | PDF Full-text (3177 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Morphology and porosity are crucial aspects for designing electrodes with facile transport of electrons, ions and matter, which is a key parameter for electrochemical energy storage and conversion. Carbon nanofibers (CNFs) prepared by electrospinning are attractive for their high aspect ratio, inter-fiber macroporosity [...] Read more.
Morphology and porosity are crucial aspects for designing electrodes with facile transport of electrons, ions and matter, which is a key parameter for electrochemical energy storage and conversion. Carbon nanofibers (CNFs) prepared by electrospinning are attractive for their high aspect ratio, inter-fiber macroporosity and their use as self-standing electrodes. The present work compares several strategies to induce intra-fiber micro-mesoporosity in self-standing CNF webs prepared by electrospinning polyacrylonitrile (PAN). Two main strategies were investigated, namely i) a templating method based on the addition of a porogen (polymethyl methacrylate, polyvinylpyrrolidone, Nafion® or ZnCl2) in the electrospinning solution of PAN, or ii) the activation in ammonia of previously formed CNF webs. The key result of this study is that open intra-fiber porosity could be achieved only when the strategies i) and ii) were combined. When each approach was applied separately, only closed intra-fiber porosity or no intra-fiber porosity was observed. In contrast, when both strategies were used in combination all CNF webs showed high mass-specific areas in the range of 325 to 1083 m2·g−1. Selected webs were also characterized for their carbon structure and electrical conductivity. The best compromise between high porosity and high electrical conductivity was identified as the fibrous web electrospun from PAN and polyvinylpyrrolidone. Full article
(This article belongs to the Special Issue Electrochemical Surface Science: Basics and Applications)
Figures

Graphical abstract

Open AccessArticle
Potential Dependent Structure and Stability of Cu(111) in Neutral Phosphate Electrolyte
Surfaces 2019, 2(1), 145-158; https://doi.org/10.3390/surfaces2010012
Received: 30 January 2019 / Revised: 19 February 2019 / Accepted: 20 February 2019 / Published: 24 February 2019
Viewed by 410 | PDF Full-text (2009 KB) | HTML Full-text | XML Full-text
Abstract
Copper and copper oxide electrode surfaces are suitable for the electrochemical reduction of CO2 and produce a range of products, with the product selectivity being strongly influenced by the surface structure of the copper electrode. In this paper, we present in-situ surface [...] Read more.
Copper and copper oxide electrode surfaces are suitable for the electrochemical reduction of CO2 and produce a range of products, with the product selectivity being strongly influenced by the surface structure of the copper electrode. In this paper, we present in-situ surface X-ray diffraction studies on Cu(111) electrodes in neutral phosphate buffered electrolyte solution. The underlying mechanism of the phosphate adsorption and deprotonation of the (di)-hydrogen phosphate is accompanied by a roughening of the copper surface. A change in morphology of the copper surface induced by a roughening process caused by the formation of a mixed copper–oxygen layer could also be observed. The stability of the Cu(111) surface and the change of morphology upon potential cycling strongly depends on the preparation method and history of the electrode. The presence of copper islands on the surface of the Cu(111) electrode leads to irreversible changes in surface morphology via a 3D Cu growth mechanism. Full article
(This article belongs to the Special Issue Electrochemical Surface Science: Basics and Applications)
Figures

Figure 1

Open AccessArticle
Fe2O3 Blocking Layer Produced by Cyclic Voltammetry Leads to Improved Photoelectrochemical Performance of Hematite Nanorods
Surfaces 2019, 2(1), 131-144; https://doi.org/10.3390/surfaces2010011
Received: 31 December 2018 / Revised: 4 February 2019 / Accepted: 8 February 2019 / Published: 19 February 2019
Viewed by 409 | PDF Full-text (3447 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Hematite is a low band gap, earth abundant semiconductor and it is considered to be a promising choice for photoelectrochemical water splitting. However, as a bulk material its efficiency is low because of excessive bulk, surface, and interface recombination. In the present work, [...] Read more.
Hematite is a low band gap, earth abundant semiconductor and it is considered to be a promising choice for photoelectrochemical water splitting. However, as a bulk material its efficiency is low because of excessive bulk, surface, and interface recombination. In the present work, we propose a strategy to prepare a hematite (α-Fe2O3) photoanode consisting of hematite nanorods grown onto an iron oxide blocking layer. This blocking layer is formed from a sputter deposited thin metallic iron film on fluorine doped tin oxide (FTO) by using cyclic voltammetry to fully convert the film into an anodic oxide. In a second step, hematite nanorods (NR) are grown onto the layer using a hydrothermal approach. In this geometry, the hematite sub-layer works as a barrier for electron back diffusion (a blocking layer). This suppresses recombination, and the maximum of the incident photon to current efficiency is increased from 12% to 17%. Under AM 1.5 conditions, the photocurrent density reaches approximately 1.2 mA/cm2 at 1.5 V vs. RHE and the onset potential changes to 0.8 V vs. RHE (using a Zn-Co co-catalyst). Full article
(This article belongs to the Special Issue Photon Driven Dynamics at Surfaces)
Figures

Graphical abstract

Open AccessArticle
Ultrafast Vibrational Dynamics of CO Ligands on RuTPP/Cu(110) under Photodesorption Conditions
Surfaces 2019, 2(1), 117-130; https://doi.org/10.3390/surfaces2010010
Received: 16 December 2018 / Revised: 21 January 2019 / Accepted: 3 February 2019 / Published: 7 February 2019
Cited by 1 | Viewed by 462 | PDF Full-text (2735 KB) | HTML Full-text | XML Full-text
Abstract
We have studied CO coordinated to ruthenium tetraphenylporphyrin (RuTPP)/Cu(110) and directly adsorbed to Cu(110), using femtosecond pump-sum frequency probe spectroscopy, to alter the degree of electron-vibration coupling between the metal substrate and CO. We observe the facile femtosecond laser-induced desorption of CO from [...] Read more.
We have studied CO coordinated to ruthenium tetraphenylporphyrin (RuTPP)/Cu(110) and directly adsorbed to Cu(110), using femtosecond pump-sum frequency probe spectroscopy, to alter the degree of electron-vibration coupling between the metal substrate and CO. We observe the facile femtosecond laser-induced desorption of CO from RuTPP/Cu(110), but not from Cu(110). A change in the vibrational transients, in the first few picoseconds, from a red- to blue-shift of the C–O stretching vibration under photodesorption conditions, was also observed. This drastic change can be explained, if the cause of the C–O frequency redshift of Cu(110) is not the usually-assumed anharmonic coupling to low frequency vibrational modes, but a charge transfer from hot electrons to the CO 2π* state. This antibonding state shifts to higher energies on RuTPP, removing the C–O redshift and, instead, reveals a blueshift, predicted to arise from electron-mediated coupling between the coherently excited internal stretch and low frequency modes in the system. Full article
(This article belongs to the Special Issue Photon Driven Dynamics at Surfaces)
Figures

Graphical abstract

Open AccessArticle
Characterization and Neutral Atom Beam Surface Modification of a Clear Castable Polyurethane for Biomicrofluidic Applications
Surfaces 2019, 2(1), 100-116; https://doi.org/10.3390/surfaces2010009
Received: 1 December 2018 / Revised: 19 January 2019 / Accepted: 26 January 2019 / Published: 1 February 2019
Viewed by 459 | PDF Full-text (3763 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Polyurethanes (PU) are a broad class of polymers that offer good solvent compatibility and a wide range of properties that can be used to generate microfluidic layers. Here, we report the first characterization of a commercially available Shore 80D polyurethane (Ultraclear™ 480N) for [...] Read more.
Polyurethanes (PU) are a broad class of polymers that offer good solvent compatibility and a wide range of properties that can be used to generate microfluidic layers. Here, we report the first characterization of a commercially available Shore 80D polyurethane (Ultraclear™ 480N) for biomicrofluidic applications. Studies included comparing optical clarity with Polydimethylsiloxane (PDMS) and using high-fidelity replica molding to produce solid PU structures from the millimeter to nanometer scales. Additionally, we report the first use of NanoAccel™ treatment in Accelerated Neutral Atom Beam (ANAB) mode to permanently roughen the surface of PU and improve the adhesion of breast cancer cells (MDA-MB-231) on PU. Surface energy measurements using Owens-Wendt equations indicate an increase in polar and total surface energy due to ANAB treatment. Fourier-transform infrared (FTIR) spectroscopy in attenuated total reflectance (ATR) mode was used to demonstrate that the treatment does not introduce any new types of functional groups on the surface of Ultraclear™ PU. Finally, applicability in rapid prototyping for biomicrofluidics was demonstrated by utilizing a 3D-printing-based replica molding strategy to create PU microfluidic layers. These layers were sealed to polystyrene (PS) bases to produce PU-PS microfluidic chips. Ultraclear™ PU can serve as a clear and castable alternative to PDMS in biomicrofluidic studies. Full article
Figures

Graphical abstract

Open AccessArticle
Interface Science Using Ambient Pressure Hard X-ray Photoelectron Spectroscopy
Surfaces 2019, 2(1), 78-99; https://doi.org/10.3390/surfaces2010008
Received: 18 December 2018 / Revised: 23 January 2019 / Accepted: 24 January 2019 / Published: 28 January 2019
Viewed by 613 | PDF Full-text (3629 KB) | HTML Full-text | XML Full-text
Abstract
The development of novel in situ/operando spectroscopic tools has provided the opportunity for a molecular level understanding of solid/liquid interfaces. Ambient pressure photoelectron spectroscopy using hard X-rays is an excellent interface characterization tool, due to its ability to interrogate simultaneously the chemical composition [...] Read more.
The development of novel in situ/operando spectroscopic tools has provided the opportunity for a molecular level understanding of solid/liquid interfaces. Ambient pressure photoelectron spectroscopy using hard X-rays is an excellent interface characterization tool, due to its ability to interrogate simultaneously the chemical composition and built-in electrical potentials, in situ. In this work, we briefly describe the “dip and pull” method, which is currently used as a way to investigate in situ solid/liquid interfaces. By simulating photoelectron intensities from a functionalized TiO2 surface buried by a nanometric-thin layer of water, we obtain the optimal photon energy range that provides the greatest sensitivity to the interface. We also study the evolution of the functionalized TiO2 surface chemical composition and correlated band-bending with a change in the electrolyte pH from 7 to 14. Our results provide general information about the optimal experimental conditions for characterizing the solid/liquid interface using the “dip and pull” method, and the unique possibilities offered by this technique. Full article
(This article belongs to the Special Issue Electrochemical Surface Science: Basics and Applications)
Figures

Graphical abstract

Open AccessArticle
Oxygen Reduction Reaction on Polycrystalline Platinum: On the Activity Enhancing Effect of Polyvinylidene Difluoride
Surfaces 2019, 2(1), 69-77; https://doi.org/10.3390/surfaces2010007
Received: 20 December 2018 / Revised: 18 January 2019 / Accepted: 21 January 2019 / Published: 24 January 2019
Viewed by 413 | PDF Full-text (1971 KB) | HTML Full-text | XML Full-text
Abstract
There have been several reports concerning the performance improving properties of additives, such as polyvinylidene difluoride (PVDF), to the membrane or electrocatalyst layer of proton exchange membrane fuel cells (PEMFC). However, it is not clear if the observed performance enhancement is due to [...] Read more.
There have been several reports concerning the performance improving properties of additives, such as polyvinylidene difluoride (PVDF), to the membrane or electrocatalyst layer of proton exchange membrane fuel cells (PEMFC). However, it is not clear if the observed performance enhancement is due to kinetic, mass transport, or anion blocking effects of the PVDF. In a previous investigation using a thin-film rotating disk electrode (RDE) approach (of decreased complexity as compared to membrane electrode assembly (MEA) tests), a performance increase for the oxygen reduction reaction (ORR) could be confirmed. However, even in RDE measurements, reactant mass transport in the catalyst layer cannot be neglected. Therefore, in the present study, the influence of PVDF is re-examined by coating polycrystalline bulk Pt electrodes by PVDF and measuring ORR activity. The results on polycrystalline bulk Pt indicate that the effects of PVDF on the reaction kinetics and anion adsorption are limited, and that the observed performance increase on high surface area Pt/C most likely is due to an erroneous estimation of the electrochemical active surface area (ECSA) from CO stripping and Hupd. Full article
(This article belongs to the Special Issue Electrochemical Surface Science: Basics and Applications)
Figures

Graphical abstract

Open AccessArticle
Surface Investigation on Electrochemically Deposited Lead on Gold
Surfaces 2019, 2(1), 56-68; https://doi.org/10.3390/surfaces2010006
Received: 17 December 2018 / Revised: 11 January 2019 / Accepted: 14 January 2019 / Published: 17 January 2019
Viewed by 365 | PDF Full-text (2497 KB) | HTML Full-text | XML Full-text
Abstract
Electrodeposition of Pb on Au has been of interest for the variety of surface phenomena such as the UnderPotential Deposition (UPD) and surface alloying. Here, we examined the interface between the electrodeposited Pb film on Au, using surface sensitive techniques such as X-ray [...] Read more.
Electrodeposition of Pb on Au has been of interest for the variety of surface phenomena such as the UnderPotential Deposition (UPD) and surface alloying. Here, we examined the interface between the electrodeposited Pb film on Au, using surface sensitive techniques such as X-ray Photoelectron Spectroscopy (XPS), Ultraviolet Photoelectron Spectroscopy (UPS), Energy-Filtered Photoemission Electron Microscopy (EF-PEEM) and Work Function (WF) mapping. The initially electrodeposited Pb overlayer (~4 ML equivalent thickness) was transferred from the electrochemical cell to the UHV system. The deposited Pb layer was subjected to Argon sputtering cycles to remove oxide formed due to air exposure and gradually thinned down to a monolayer level. Surface science acquisitions showed the existence of a mixed oxide/metallic Pb overlayer at the monolayer level that transformed to a metallic Pb upon high temperature annealing (380 °C for 1 h) and measured changes of the electronic interaction that can be explained by Pb/Au surface alloy formation. The results show the electronic interaction between metallic Pb and Au is different from the interaction of Au with the PbO and Pb/PbO mixed layer; the oxide interface is less strained so the surface stress driven mixing between Au is not favored. The work illustrates applications of highly surface sensitive methods in the characterization of the surface alloy systems that can be extended to other complex and ultrathin mixed-metallic systems (designed or spontaneously formed). Full article
(This article belongs to the Special Issue Electrochemical Surface Science: Basics and Applications)
Figures

Figure 1

Open AccessEditorial
Acknowledgement to Reviewers of Surfaces in 2018
Surfaces 2019, 2(1), 54-55; https://doi.org/10.3390/surfaces2010005
Published: 16 January 2019
Viewed by 241 | PDF Full-text (139 KB) | HTML Full-text | XML Full-text
Abstract
Rigorous peer-review is the corner-stone of high-quality academic publishing [...] Full article
Open AccessArticle
Co3O4 Nanopetals on Si as Photoanodes for the Oxidation of Organics
Surfaces 2019, 2(1), 41-53; https://doi.org/10.3390/surfaces2010004
Received: 13 November 2018 / Revised: 8 January 2019 / Accepted: 9 January 2019 / Published: 11 January 2019
Viewed by 388 | PDF Full-text (7765 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Cobalt oxide nanopetals were grown on silicon electrodes by heat-treating metallic cobalt films deposited by DC magnetron sputtering. We show that cobalt oxide, with this peculiar nanostructure, is active towards the photo-electrochemical oxidation of water as well as of organic molecules, and that [...] Read more.
Cobalt oxide nanopetals were grown on silicon electrodes by heat-treating metallic cobalt films deposited by DC magnetron sputtering. We show that cobalt oxide, with this peculiar nanostructure, is active towards the photo-electrochemical oxidation of water as well as of organic molecules, and that its electrochemical properties are directly linked to the structure of its surface. The formation of Co3O4 nanopetals, induced by oxidizing annealing at 300 °C, considerably improves the performance of the material with respect to simple cobalt oxide films. Photocurrent measurements and electrochemical impedance are used to explain the behavior of the different structures and to highlight their potential application in water remediation technologies. Full article
(This article belongs to the Special Issue Electrochemical Surface Science: Basics and Applications)
Figures

Graphical abstract

Open AccessArticle
X-ray Absorption under Operating Conditions for Solid-Oxide Fuel Cells Electrocatalysts: The Case of LSCF/YSZ
Surfaces 2019, 2(1), 32-40; https://doi.org/10.3390/surfaces2010003
Received: 5 December 2018 / Revised: 19 December 2018 / Accepted: 2 January 2019 / Published: 8 January 2019
Viewed by 445 | PDF Full-text (3060 KB) | HTML Full-text | XML Full-text
Abstract
We describe a novel electrochemical cell for X-ray absorption spectroscopy (XAS) experiments during electrical polarization suitable for high-temperature materials such as those used in solid oxide fuel cells. A half-cell LSCF/YSZ was then investigated under cathodic and anodic conditions (850 °C and applied [...] Read more.
We describe a novel electrochemical cell for X-ray absorption spectroscopy (XAS) experiments during electrical polarization suitable for high-temperature materials such as those used in solid oxide fuel cells. A half-cell LSCF/YSZ was then investigated under cathodic and anodic conditions (850 °C and applied electrical bias ranging from +1 V to −1 V in air). The in situ XAS measurements allowed us to follow the LSCF degradation into simple oxides. The rapid deterioration of LSCF is ascribed to the formation of excess of oxygen vacancies leading to the collapse of the mixed perovskite structure. Full article
(This article belongs to the Special Issue Electrochemical Surface Science: Basics and Applications)
Figures

Graphical abstract

Open AccessArticle
Methanol Oxidation on Graphenic-Supported Platinum Catalysts
Surfaces 2019, 2(1), 16-31; https://doi.org/10.3390/surfaces2010002
Received: 19 November 2018 / Revised: 28 December 2018 / Accepted: 29 December 2018 / Published: 6 January 2019
Cited by 1 | Viewed by 541 | PDF Full-text (2915 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Graphene oxide (GO), reduced graphene oxide by thermal treatment (rGO-TT), nitrogen-modified rGO (N-rGO), and carbon Vulcan were synthesized and employed in the current work as catalyst support for Pt nanoparticles, to study their properties and impact toward the methanol oxidation reaction (MOR) in [...] Read more.
Graphene oxide (GO), reduced graphene oxide by thermal treatment (rGO-TT), nitrogen-modified rGO (N-rGO), and carbon Vulcan were synthesized and employed in the current work as catalyst support for Pt nanoparticles, to study their properties and impact toward the methanol oxidation reaction (MOR) in sulfuric acid medium. Several physicochemical techniques, such as X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), Transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Raman, and elemental analysis were employed to characterize the novel materials, while potentiodynamic and potentiostatic methods were used to study catalytic performance toward the methanol oxidation reaction in acidic medium. The main results indicate a high influence of the support on the surface electronic state of the catalyst, and consequently the catalytic performance toward the MOR is modified. Accordingly, Pt/N-rGO and Pt/rGO-TT show the lowest and the highest catalytic performance toward the MOR, respectively. Full article
(This article belongs to the Special Issue Electrochemical Surface Science: Basics and Applications)
Figures

Graphical abstract

Open AccessArticle
Electrochemical Behavior of Pt–Ru Catalysts Supported on Graphitized Ordered Mesoporous Carbons toward CO and Methanol Oxidation
Surfaces 2019, 2(1), 1-15; https://doi.org/10.3390/surfaces2010001
Received: 29 November 2018 / Revised: 21 December 2018 / Accepted: 27 December 2018 / Published: 3 January 2019
Cited by 1 | Viewed by 453 | PDF Full-text (2809 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this work, graphitized ordered mesoporous carbons (gCMK-3) were employed as support for Pt and Pt–Ru nanoparticles synthesized by different reduction methods. The catalysts displayed metal contents and Pt:Ru atomic ratios close to 20 wt % and 1:1, respectively. A comparison of the [...] Read more.
In this work, graphitized ordered mesoporous carbons (gCMK-3) were employed as support for Pt and Pt–Ru nanoparticles synthesized by different reduction methods. The catalysts displayed metal contents and Pt:Ru atomic ratios close to 20 wt % and 1:1, respectively. A comparison of the physical parameters of Pt and Pt–Ru catalysts demonstrated that Ru enters into the Pt crystal structure, with well-dispersed nanoparticles on the carbon support. The Pt catalysts exhibited similar surface oxide composition, whereas a variable content of surface Pt and Ru oxides was found for the Pt–Ru catalysts. As expected, the Pt–Ru catalysts showed low CO oxidation onset and peak potentials, which were attributed to the high relative abundances of both metallic Pt and Ru oxides. All the studied catalysts exhibited higher maximum current densities than those observed for the commercial Pt and Pt–Ru catalysts, although the current–time curves at 0.6 V vs. reversible hydrogen electrode (RHE) demonstrated a slightly higher stationary current density in the case of the Pt/C commercial catalyst compared with Pt nanoparticles supported on gCMK-3s. However, the stationary currents obtained from the Pt–Ru/gCMK-3 catalysts surpassed those of the commercial Pt–Ru material, suggesting the suitability of the prepared catalysts as anodes for these devices. Full article
(This article belongs to the Special Issue Electrochemical Surface Science: Basics and Applications)
Figures

Graphical abstract

Surfaces EISSN 2571-9637 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top