Removing Polyvinylpyrrolidone from Catalytic Pt Nanoparticles without Modification of Superficial Order

Monzó, Javier; Koper, Marc T. M.; Rodríguez, Paramaconi

doi:10.1002/cphc.201100894

Cited by 73 publications

(69 citation statements)

References 53 publications

(90 reference statements)

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“…decrease for increasing amounts of H2SO4, is also observed for the (111)-related peak, although this signal is less visible due to the low (111) character of these Pt nanoparticles. The voltammetric profiles reported here as a consequence of the presence of H2SO4 in the synthesis step are qualitatively similar to those obtained with Pt nanoparticles prepared in similar water-in-oil microemulsions but in the presence of HCl [6] and with Pt nanoparticles prepared with different capping materials (sodium polyacrylate (NaPa), [8][9][10] tetradecyltrimethylammonium bromide (TTAB), [11][12][13] poly(vinylpyrrolidone) (PVP) [14,15] or oleic acid/oleylamine [15] ) by means of various colloidal routes, in all of which cubic Pt nanoparticles were synthesised. In this regard, it is important to recall that, by simple analogy with the unit stereographic triangle of a fcc metal, a stereographic triangle with shaped fcc metal nanoparticles can be made in which the three apexes represent the coordinates of polyhedral nanocrystals bounded by basal facets (a cube, octahedron and rhombic dodecahedron enclosed by (100), (111) and (110) faces, respectively).…”

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confidence: 74%

Synthesis and Electrocatalytic Properties of H₂SO₄‐Induced (100) Pt Nanoparticles Prepared in Water‐in‐Oil Microemulsion

et al. 2014

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The increasing number of applications for shape-controlled metal nanoparticles leads to the need of easy, cheap and scalable methodologies. In this communication we report, the synthesis of (100) preferentially oriented platinum (Pt) nanoparticles with 9 nm particle size using a water-in-oil microemulsion method. The specific surface structure of the nanoparticles is induced by the presence of H2SO4 in the water phase of the microemulsion. Interestingly, the results here reported will show how increasing amounts of H2SO4 lead to the formation of Pt nanoparticles containing a higher amount of (100) sites on their surface. This preferential surface orientation has been confirmed electrochemically by using the so-called hydrogen adsorption/desorption process. In addition, TEM measurements have confirmed the presence of cubic-like Pt nanoparticles. Finally, the electrocatalytic properties of the Pt nanoparticles have been evaluated towards ammonia and CO electro-oxidations as (100) structure sensitive reactions.Several methodologies for shape control of metal nanoparticles have been developed in the past decade with the main objective of controlling the specific arrangements of the atoms at their surface, that is, their surface structure. [1][2][3][4] In this way, as widely demonstrated with metal single crystals as model electrodes, the catalytic properties of the metal nanostructures can be tuned and optimised for a particular reaction. Among others, and due to its unique catalytic properties, Pt nanoparticles have been the focus of numerous studies from which their remarkable surface structure sensitivity has been illustrated and discussed for several reactions of interest. [1,5] On the other hand, from a more applied point of view, it would be desirable to have a simple, fast and economically viable methodology for the preparation of such shapecontrolled metal nanoparticles to be then scalable for large scale applications. However, most of the developed synthetic routes do not fulfil with these requirements and consequently, the scalability still remains a challenge. In this regard, in a very recent publication, we have extended the use of water-in-oil microemulsions, traditionally employed for the preparation of metal nanoparticles with controlled atomic composition and size, for the preparation of shape-controlled Pt nanoparticles. In particular, we have reported that the addition of determined amounts of HCl in the water phase of the microemulsion led to the formation of Pt nanoparticles with a bell-shaped preferential (100) surface structure with a maximum of the (100) character at about 25% of HCl.[6] This approach opens new possibilities in terms of scalability because the handling of the water-in-oil microemulsions is easy, fast, economic and frequently performed at room temperature. In this communication, we will show that H2SO4 can be also used as effective (100) surface modifier during the preparation of Pt nanoparticles in microemulsion (see experimental section for details). The resulting Pt nanopart...

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confidence: 74%

Synthesis and Electrocatalytic Properties of H₂SO₄‐Induced (100) Pt Nanoparticles Prepared in Water‐in‐Oil Microemulsion

et al. 2014

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“…2c still occurs. Koper [39] reported that PVP-stabilised Pt could be cleaned in a solution of H 2 O 2 /H 2 SO 4 where Pt catalyses the decomposition of H 2 O 2 into water and O 2 . It was suggested that PVP was physically removed by the generated oxygen bubbles.…”

Section: Resultsmentioning

confidence: 99%

Probing the surface oxidation of chemically synthesised gold nanospheres and nanorods

2014

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In this study, the electrochemical behaviour of commercially available gold spheres and rods stabilised by carboxylic acid and cetyl trimethyl ammonium bromide (CTAB) moieties, respectively, are investigated. The cyclic voltammetric behaviour in acidic electrolyte is distinctly different with the nanorods exhibiting unusual oxidative behaviour due to an electrodissolution process. The nanospheres exhibited responses typical of a highly defective surface which significantly impacted on electrocatalytic activity. A repetitive potential cycling cleaning procedure was also investigated which did not improve the activity of the nanorods and resulted in deactivating the gold spheres due to decreasing the level of surface defects.

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“…However, this cleaning resulted ineffective with shaped Pt nanoparticles prepared with polyvinylpyrrolidone (PVP) [37,39] which is one of the most usual capping agents for the preparation of shape-controlled metal nanoparticles [40]. To the best of our knowledge, the first example of clean shape-controlled Pt nanoparticles prepared with PVP was reported by Monzó et al [41 ]. They proposed the use of a H 2 O 2 /H 2 SO 4 solution to remove the PVP.…”

Section: Surface Cleaning Methodologiesmentioning

confidence: 99%

Electrocatalysis on shape-controlled metal nanoparticles: Progress in surface cleaning methodologies

Montiel

Vidal‐Iglesias

Montiel

et al. 2017

Current Opinion in Electrochemistry

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The use of shape-controlled metal nanoparticles has produced not only a clear enhancement in the electrocatalytic activity of different reactions of interest but also a better understanding of the effect of the surface structure on nanoscaled materials. However, it is well-accepted that a correct understanding of the correlations between shape/surface structure and electrochemical reactivity indispensably requires the use of clean surfaces. In this regard, and considering that most of the synthetic methodologies available in the literature for the preparation of these shaped metal nanoparticles employ capping agents, the development of effective surface cleaning methodologies able to remove such capping agents from the surface of the corresponding nanoparticles, becomes an extremely important prerequisite to subsequently evaluate their electrocatalytic properties for any reaction of interest.Consequently, in this contribution, we summarize the most relevant advances about surface cleaning procedures applied to different shaped metal nanoparticles for electrocatalytic purposes. It is worth mentioning that this work will only include contributions in which the surface cleanness of the samples is specifically evaluated using well-established electrochemical tools.

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Removing Polyvinylpyrrolidone from Catalytic Pt Nanoparticles without Modification of Superficial Order

Cited by 73 publications

References 53 publications

Synthesis and Electrocatalytic Properties of H₂SO₄‐Induced (100) Pt Nanoparticles Prepared in Water‐in‐Oil Microemulsion

Synthesis and Electrocatalytic Properties of H₂SO₄‐Induced (100) Pt Nanoparticles Prepared in Water‐in‐Oil Microemulsion

Probing the surface oxidation of chemically synthesised gold nanospheres and nanorods

Electrocatalysis on shape-controlled metal nanoparticles: Progress in surface cleaning methodologies

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Removing Polyvinylpyrrolidone from Catalytic Pt Nanoparticles without Modification of Superficial Order

Cited by 73 publications

References 53 publications

Synthesis and Electrocatalytic Properties of H2SO4‐Induced (100) Pt Nanoparticles Prepared in Water‐in‐Oil Microemulsion

Synthesis and Electrocatalytic Properties of H2SO4‐Induced (100) Pt Nanoparticles Prepared in Water‐in‐Oil Microemulsion

Probing the surface oxidation of chemically synthesised gold nanospheres and nanorods

Electrocatalysis on shape-controlled metal nanoparticles: Progress in surface cleaning methodologies

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Product

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Synthesis and Electrocatalytic Properties of H₂SO₄‐Induced (100) Pt Nanoparticles Prepared in Water‐in‐Oil Microemulsion

Synthesis and Electrocatalytic Properties of H₂SO₄‐Induced (100) Pt Nanoparticles Prepared in Water‐in‐Oil Microemulsion