Highly Catalytic Pt Nanoparticles Grown in Two ... - ACS Publications

Subscriber access provided by University of Rochester | River Campus & Miner Libraries

Letter

Highly Catalytic Pt Nanoparticles Grown in TwoDimensional Conducting Polymers at the Air-Water Interfaces Kyoungwook Kim, Hyungmin Ahn, and Moon Jeong Park ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.7b10821 • Publication Date (Web): 30 Aug 2017 Downloaded from http://pubs.acs.org on August 30, 2017

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

ACS Applied Materials & Interfaces is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 18

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

Highly Catalytic Pt Nanoparticles Grown in Two-Dimensional Conducting Polymers at the Air-Water Interfaces

Kyoungwook Kim1, Hyungmin Ahn2, and Moon Jeong Park1,2* 1

Division of Advanced Materials Science, 2Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, Korea 790-784

* Corresponding author ([email protected])

KEYWORDS: 2D polymers, Pt nanoparticles, Electrocatalysts, Methanol oxidation, Air-water interfaces

ACS Paragon Plus Environment

1


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 18

Abstract We report a new approach to the synthesis of uniform, high areal density Pt nanocrystals supported by conducting polymers. The key strategy is the use of ice-templated, two-dimensional polyaniline nanosheets at the air-water interface as a platform for expediting Pt nucleation. Highly crystalline Pt nanoparticles with a narrow size distribution of 2.7 ± 0.3 nm and a high electrochemically active surface area of 94.57 m2/g were obtained. Pt NPs were strongly anchored to the polyaniline nanosheets, and demonstrated high current densities, good durability for the methanol oxidation reaction, and excellent carbon monoxide tolerance, all of which are unprecedented. The idea established in this study could be applied to the production of a wide range of other catalysts with enhanced activities.


2

Page 3 of 18

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Pt nanoparticles (Pt NPs) are known to be the most effective anodic electrocatalysts.1-3 Carbon-supported Pt NPs are widely investigated forms of these catalysts, and they have revealed that the size and shape of the Pt NPs are the keys to their catalytic properties.4-7 However, the carbon supports do not prevent particle agglomeration, resulting in loss of catalytic activity over time.8,9 The fact that the preparation of carbon-supported Pt NPs requires high reaction temperatures10,11 and/or the use of expensive structural carbons12,13 is also a constraint. The ecofriendly and cost-effective synthesis of Pt NPs with high catalytic activities is thus of primary importance. With this in mind, a great deal of attention has been devoted to conducting polymer-supported Pt NPs,14 with polyaniline (PANI) being the most studied conducting polymer due to its high reduction potential and the amine moieties in its backbone.1517

These factors facilitate the nucleation and growth of Pt NPs in PANI even at room

temperature, allowing them to be firmly anchored to the conducting structures.17-19 Given that the electrical conductivity and electrochemical stability of PANI are largely influenced by its morphology,20-22 a uniform dispersion of Pt NPs in nanostructured PANI could be a promising avenue for improving the catalytic properties of the nanoparticles. The large surface area of nanostructured PANI could also help to reduce CO-poisoning of Pt NPs,18,23 which has been a pressing challenge in the field of Pt-based electrocatalysts for decades. Nevertheless, there is no knowledge about increasing the areal density of Pt NPs in PANI frameworks while preventing particle agglomeration. This is because of the lack of chemical control of Pt ion nucleation/reduction when it is in contact with PANI. Herein, we report the synthesis of high areal density Pt NPs anchored to PANI nanostructures through a simple and green approach. Figure 1 illustrates the synthesis of PANIsupported Pt NPs at the air-water interface schematically. First, highly conductive, two-


3


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 4 of 18

dimensional PANI nanosheets with thicknesses of ca. 30-40 nm that were non-porous, had areas of a few centimeters squared and small rms roughness less than 2 nm were synthesized on ice surfaces.22 The electrical conductivity of PANI nanosheets was determined to be 29 S cm-1 at room temperature. Details are provided in Figure S1 of Supporting Information. The PANI nanosheet was transferred to the surface of water containing 0.5 mM K2PtCl4. The solution was heated to 70 °C for 5 min without any stirring. This lead to the PtCl42- ion clusters rapidly and spontaneously floating to decrease the surface tension of the water, which is key to achieving high areal density Pt NPs. There is no doubt that placing the PANI nanosheets at the air-water interface reduces the surface tension of water. However, the surface tension of HCl-doped PANI is known to be around 70 mN/m at 20°C,24,25 and therefore the reduction is considered to be small. In addition, the location of the PANI nanosheets at the water surface creates a new interface of solid (PANI) and liquid (water), which provides a platform to have attractive interactions between ion clusters and the PANI nanosheets. This resulted in the formation of complexes with the secondary amines (or tertiary imines) of the PANI nanosheets. Exposing the complexes to formic acid resulted in the formation of Pt NPs anchored to the PANI nanosheets. The Pt contents in the 2D PANI nanosheets measured using inductively coupled plasma atomic emission spectroscopy were in range 35-41 wt.%.


4

Page 5 of 18

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 1. Schematic illustration of the synthesis of Pt NPs supported on PANI nanosheets at the air-water interface. Photograph and TEM image of the PANI nanosheets are also shown.

The morphology of Pt NPs grown in two-dimensional PANI nanosheets was investigated by transmission electron microscopy (TEM). As shown in Figure 2a, markedly high areal density Pt NPs supported by PANI nanosheets were obtained. The TEM image analysis shown in the inset histogram found an average particle diameter of 2.7 ± 0.3 nm. The magnified TEM image also shown in the inset of Figure 2a demonstrates the formation of finely dispersed, uniform Pt NPs, where some of them were observed to form a string.


5


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 6 of 18

The crystalline structures of the Pt NPs supported by the PANI nanosheets were investigated by powder X-ray diffraction (XRD) experiments. As shown in Figure 2b, the XRD profile shows the presence of (111), (200), (220), (311), and (222) planes in the Pt nanocrystals, which were packed into face-centered cubic lattices. The average size of the Pt NPs as estimated by the Scherrer equation26 was 4.36 nm. Other peaks at 2θ = 24.8° and 27.9° correspond to the (002) and (020) planes of orthorhombic PANI crystals in the P222 space group.22 The highresolution TEM (HR-TEM) image shown in the inset of Figure 2b confirms the spherical shape of the highly crystalline Pt NPs embedded in the PANI support. Additional TEM images are provided in Figure S2 of Supporting Information. X-ray photoelectron spectroscopy (XPS) was used to provide a better understanding of the mechanisms underlying the synthesis of the Pt NPs at the air-water interface. When the PANI nanosheet was taken from the surface of water containing K2PtCl4 after heating for 5 min, the migration of Pt(II) ion clusters into PANI was revealed by the presence of two peaks at 72.8 and 76.0 eV, as shown in Figure 2c. Chemical reduction by formic acid resulted in distinct shifts of these peaks to 71.5 and 74.8 eV, corresponding to Pt4f7/2 and Pt4f5/2, respectively. The deconvoluted peaks show that 83.8% of Pt(II) was reduced to Pt(0). It is thus inferred that large numbers of well-organized molecular binding sites throughout the crystalline PANI nanosheets located at the air-water interface effectively nucleate the Pt ion clusters, leading to the formation of only 2.7 nm sized Pt NPs. We want to stress that the Pt NPs were synthesized in-situ within the 2D PANI nanosheets. Pt ion clusters can diffuse and penetrate the PANI nanosheets at the air-water interface, yielding homogeneously distributed Pt NPs after reduction (Figure S3 of Supporting Information). We have conducted a control experiment by placing the PANI nanosheets on the


6

Page 7 of 18

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


bottom of petri dish to reduce the Pt ions in solutions first and then adsorb the Pt NPs to the PANI nanosheets. In this case, the adsorption of Pt NPs occurred mostly at the surfaces of PANI nanosheets and they were severely aggregated (Figure S3).

Figure 2. (a) TEM image of Pt NPs supported by a PANI nanosheet, showing finely dispersed, uniform Pt NPs. The magnified TEM image and histogram in the insets indicate the average particle diameter (2.7 ± 0.3 nm). (b) XRD profile and high resolution TEM image of high crystalline Pt NPs packed into a face-centered cubic lattice, as indexed in the figure. (c) XPS spectra of Pt ion clusters on PANI and Pt NPs on PANI taken after each synthetic step. (d) FT-IR spectra of PANI nanosheets before and after synthesis of Pt NPs. Characteristic PANI peaks are assigned in the figure.


7


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 8 of 18

It should be noted here that the Fourier transform infrared (FT-IR) spectra revealed changes in the vibrational states of the PANI nanosheet as a result of the synthesis of Pt NPs. As shown in Figure 2d, the characteristic peaks of PANI were shifted to higher wavenumber upon anchoring Pt NPs, signaling the changes in the resonance structure of PANI. The large blue shift (26 cm-1) of N=Q=N stretching is particularly noteworthy, as it is in direct contact with Pt d orbitals.27 It has been further revealed that the strong interaction between Pt and PANI altered the ratio of IR peak intensity at 1500 cm-1 (benzoid ring) and 1570 cm-1 (quinoid ring).28 In other words, the quinoid ring vibration became stronger after synthesizing Pt NPs in PANI, indicating that Pt d orbitals interact with the π-conjugated structure of PANI, especially through the quinoid ring. Such electron transfer allows the formation of Pt-N bonds to retard the dissolution and detachment of Pt during electro-catalysis.16,29 Figure 3a shows cyclic voltammograms (CVs) of Pt NPs supported by PANI nanosheets (Pt loading of 35 wt.%) as measured in an aqueous solution containing 0.1 M HClO4 and 1 M methanol at a scan rate of 50 mV/s and a temperature of 25 °C. The peak current density in the forward scan (If) occurred at around 0.7 V is corresponding to methanol oxidation, while that in the backward scan (Ib) occurred at approximately 0.5 V is associated with the oxidation of intermediate carbonaceous species. Hydrogen adsorption/desorption were also seen in the -0.2−0.1 V region. Intriguingly, the If/Ib value was as high as 2.45 for the first scan, and it remained as high as 1.84 even after 50 cycles. It is also worth noting that the peak current density only decreased by 8% after 50 cycles. This indicates good CO tolerance and the high durability of the PANI-supported Pt NPs for methanol electro-oxidation, which are both attributed to the finely dispersed Pt NPs on the PANI nanosheets and the Pt-N interaction to have efficient electron transfer.16 This prevents the aggregation/sintering of Pt NPs and makes it difficult for Pt


8

Page 9 of 18

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


NPs to be oxidized. We also consider the steric effects by well-organized PANI chains surrounding Pt NPs, impeding the adsorption of carbonaceous species on the catalyst surfaces. These results contrast strikingly with those obtained for commercial Pt/C catalysts (Pt loading of 40 wt.%). As shown in Figure 3b, the peak current densities obtained with Pt/C were approximately 2 times lower than those obtained with the PANI-supported Pt NPs. The current decreased significantly with cycle number, with only 60% of the initial value being retained after 50 cycles. The If/Ib value of Pt/C was as low as 0.92, in good agreement with the literature.30-32 The improved electrochemical stability of the PANI-supported Pt NPs toward methanol oxidation was further confirmed by chronoamperometry, as shown in Figure S4 of Supporting Information. The results obtained thus far lead us to conclude that two-dimensional PANI nanosheets at the air-water interface can be a new platform for the synthesis of uniform and high areal density Pt NPs. Note that the electrochemically active surface area (ECSA) of the PANIsupported Pt NPs (35%) as measured in 0.1 M HClO4 aqueous solution was 94.57 m2/g whereas that of commercial Pt/C (40%) was 41.73 m2/g (Figure S5). We conclude this paper by commenting on the role of the surface tension of water in contact with air in determining the size and distribution of the Pt NPs. The specific interaction between amine sites of PANI and Pt ion clusters is absolutely the key to synthesize Pt NPs on the PANI nanosheets. This is true for almost all PANI/metal NPs composites reported in literature regardless of the form of PANI (particles,33 wires,34 hollow structures,19 and so on). We paid our attention to unprecedentedly high areal density of Pt NPs achieved in this study despite the same underlying mechanism, suggesting that other factors should exist.


9


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 10 of 18

Most plausible reason is the unique synthesis method at the air-water interface to drive the migration of Pt ion clusters to the PANI nanosheets. We carried out control experiments where the surface tension of water was decreased by saturating the air with heptane vapor, while all other synthesis conditions remain the same. This was expected to cause the surface tension of water to decrease from 64 to 47 mN/m at 70 °C35 and therefore, the tendency of ion migration to the PANI nanosheets was less likely. The heptane vapor would also provide hydrophobic environments at the water surface, impeding the adsorption of Pt ion clusters into PANI nanosheets. This could be conjectured by XPS analysis, where the atomic percent of Pt in the PANI (before adding formic acid) decreased to less than half upon saturating the air with heptane. As a result, low areal densities were observed along with significant amounts of Pt NP aggregation, as shown in Figure 3c. This inevitably lowered the peak current densities (over twofold) and deteriorated their durability for methanol oxidation, as can be seen in Figure 3d. However, it is intriguing that the If/Ib values were still higher than those of commercial Pt/C, ranging from 1.7 to 1.9, signaling the importance of using two-dimensional PANI in good catalytic properties. The role of the areal density and distribution of Pt NPs on the PANI nanosheets in achieving high electro-catalytic properties is further discussed in Figure S6 of Supporting Information.


10

Page 11 of 18

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 3. Representative CV profiles of (a) Pt NPs supported by a PANI nanosheet, and (b) Pt NPs supported by carbon, as measured in an aqueous solution containing 0.1 M HClO4 and 1 M methanol at a scan rate of 50 mV s-1 and a temperature of 25 °C for 50 cycles. (c) TEM image of Pt NPs supported by a PANI nanosheet when the surface tension of water was decreased by saturating the air with heptane vapor. (d) Representative CV profiles of Pt NPs on PANI nanosheets by varying the surface tension of water, as measured in an aqueous solution containing 0.1 M HClO4 and 1 M methanol at a scan rate of 50 mV s-1 and at a temperature of 25 °C.


11


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 12 of 18

In summary, uniform, highly crystalline, and highly catalytically active Pt NPs with a size of 2.7 nm were embedded in a large area of a two-dimensional conducting polymer. Spontaneous and rapid clustering of Pt ions at the PANI molecular sites at the air-water interface was the key to achieving this. The If/Ib value of the PANI nanosheet-supported Pt NPs was as high as 2.45, and the high catalytic activity could be maintained well over 50 cycles. The new catalyst also demonstrated peak current densities that were two times higher than those of commercial Pt/C catalysts, along with twofold larger ECSA and improved CO tolerance.

Supporting Information The Supporting Information is available free of charge on the ACS Publications website. Characterization of materials by SPM, I-V curve, TEM, Chronoamperometry, and Cyclic voltammetry experiments, including Figures S1−S6.

Author Information Corresponding Authors [email protected] ORCID Moon Jeong Park: 0000-0003-3280-6714

Notes The authors declare no competing financial interest.

Acknowledgments This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. NRF-2017R1A2B3004763) and the Global Frontier R&D


12

Page 13 of 18

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


program on Center for Multiscale Energy System through the National Research Foundation of Korea, funded by the Ministry of Education, Science and Technology.

REFERENCES (1) Wang, L.; Imura, M.; Yamauchi, Y. Tailored Design of Architecturally Controlled Pt Nanoparticles with Huge Surface Areas toward Superior Unsupported Pt Electrocatalysts. ACS Appl. Mater. Interfaces 2012, 4, 2865–2869. (2) Li, M.; Liu, P.; Adzic, R. R. Platinum Monolayer Electrocatalysts for Anodic Oxidation of Alcohols. J. Phys. Chem. Lett. 2012, 3, 3480-3485. (3) Cheng, N.; Banis, M. N.; Liu, J.; Riese, A.; Li, X.; Li, R.; Ye, S.; Knights, S.; Sun, X. Extremely Stable Platinum Nanoparticles Encapsulated in a Zirconia Nanocage by AreaSelective Atomic Layer Deposition for the Oxygen Reduction Reaction. Adv. Mater. 2015, 27, 277–281. (4) Wang, C.; Daimon, H.; Onodera, T.; Koda, T.; Sun, S. A General Approach to the Size- and Shape-Controlled Synthesis of Platinum Nanoparticles and Their Catalytic Reduction of Oxygen. Angew. Chem. Int. Ed. 2008, 47, 3588-3591. (5) Shao, M.; Peles, A.; Shoemaker, K. Electrocatalysis on Platinum Nanoparticles: Particle Size Effect on Oxygen Reduction Reaction Activity. Nano Lett. 2011, 11, 3714-3719. (6) Bai, L.; Wang, X.; Chen, Q.; Ye, Y.; Zheng, H.; Guo, J.; Yin, Y.; Gao, C. Explaining the Size Dependence in Platinum-Nanoparticle-Catalyzed Hydrogenation Reactions. Angew. Chem. Int. Ed. 2016, 55, 15656-15661. (7) Liu, J.; Fan, X.; Liu, X.; Song, Z.; Deng, Y.; Han, X.; Hu, X.; Zhong, C. Synthesis of Cubic-Shaped Pt Particles with (100) Preferential Orientation by a Quick, One-Step and Clean Electrochemical Method. ACS Appl. Mater. Interfaces 2017, 9, 18856–18864.


13


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 14 of 18

(8) Hartl, K.; Hanzlik, M.; Arenz, M. IL-TEM Investigations on the Degradation Mechanism of Pt/C Electrocatalysts with Different Carbon Supports. Energy Environ. Sci. 2011, 4, 234238. (9) Kou, Z.; Cheng, K.; Wu, H.; Sun, R.; Guo, B.; Mu, S. Observable Electrochemical Oxidation of Carbon Promoted by Platinum Nanoparticles. ACS Appl. Mater. Interfaces 2016, 8, 3940-3947. (10) Sellin, R.; Grolleau, C.; Arrii-Clacens, S.; Pronier, S.; Clacens, J.-M.; Coutanceau, C.; Léger, J.-M. Effects of Temperature and Atmosphere on Carbon-Supported Platinum Fuel Cell Catalysts. J. Phys. Chem. C 2009, 113, 21735-21744. (11) Melke, J.; Peter, B.; Habereder, A.; Ziegler, J.; Fasel, C.; Nefedov, A.; Sezen, K.; Wöll, C.; Ehrenber, H.; Roth, C. Metal−Support Interactions of Platinum Nanoparticles Decorated N-Doped Carbon Nanofibers for the Oxygen Reduction Reaction. ACS Appl. Mater. Interfaces 2016, 8, 82-90. (12) Ye, R.; Peng, Z.; Wang, T.; Xu, Y.; Zhang, J.; Li, Y.; Nilewski, L. G.; Lin, J.; Tour, J. M. In Situ Formation of Metal Oxide Nanocrystals Embedded in Laser-Induced Graphene. ACS Nano 2015, 9, 9244-9251. (13) Lin, J.; Peng, Z.; Liu, Y.; Ruiz-Zepeda, F.; Ye, R.; Samuel, E. L. G.; Yacaman, M. J.; Yakobson, B. I.; Tour, J. M. Laser-Induced Porous Graphene Films from Commercial Polymers. Nat. Commun. 2014, 5, 5714. (14) Xu, P.; Han, X.; Zhang, B.; Du, Y.; Wang, H.-L. Multifunctional Polymer–Metal Nanocomposites via Direct Chemical Reduction by Conjugated Polymers. Chem. Soc. Rev, 2014, 43, 1349-1360. (15) Li, D.; Huang, J.; Kaner, R. B. Polyaniline Nanofibers: A Unique Polymer Nanostructure for Versatile Applications. Acc. Chem. Res. 2009, 42, 135-145. (16) Sun, X.; Zhang, N.; Huang, X. Polyaniline-Coated Platinum Nanocube Assemblies as Enhanced Methanol Oxidation Electrocatalysts. ChemCatChem 2016, 8, 3436-3440.


14

Page 15 of 18

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(17) Guo, S.; Dong, S.; Wang, E. Polyaniline/Pt Hybrid Nanofibers: High-Efficiency Nanoelectrocatalysts for Electrochemical Devices. Small 2009, 5, 1869-1876. (18) Chen, S.; Wei, Z.; Qi, X.; Dong, L.; Guo, Y.-G.; Wan, L.; Shao, Z.; Li, L. Nanostructured Polyaniline-Decorated Pt/C@PANI Core−Shell Catalyst with Enhanced Durability and Activity. J. Am. Chem. Soc. 2012, 134, 13252-13255. (19) Mondal, S.; Malik, S. Easy Synthesis Approach of Pt-Nanoparticles on Polyaniline Surface: An Efficient Electro-Catalyst for Methanol Oxidation Reaction. J. Power Sources 2016, 329, 271-279. (20) Liu, S.; Gordiichuk, P.; Wu, Z.-S.; Liu, Z.; Wei, W.; Wagner, M.; Mohamed-Noriega, N.; Wu, D.; Mai, Y.; Herrmann, A.; Müllen, K.; Feng, X. Patterning Two-Dimensional FreeStanding Surfaces with Mesoporous Conducting Polymers. Nat. Commum. 2015, 6, 8817. (21) Wang, Y.; Tran, H. D.; Liao, L.; Duan, X.; Kaner, R. B. Nanoscale Morphology, Dimensional Control, and Electrical Properties of Oligoanilines. J. Am. Chem. Soc. 2010, 132, 10365-10373. (22) Choi, I. Y.; Lee, J.; Ahn, H.; Lee, J.; Choi, H. C.; Park, M. J. High-Conductivity TwoDimensional Polyaniline Nanosheets Developed on Ice Surfaces. Angew. Chem. Int. Ed. 2015, 54, 10497-10501. (23) Wang, A.-L.; Xu, H.; Feng, J.-X.; Ding, L.-X.; Tong, Y.-X.; Li, G.-R. Design of Pd/PANI/Pd Sandwich-Structured Nanotube Array Catalysts with Special Shape Effects and Synergistic Effects for Ethanol Electrooxidation. J. Am. Chem. Soc. 2013, 135, 1070310709. (24) Wessling, B. On the Structure of Binary Conductive Polymer/Solvent Systems. Synth. Met. 1991, 41, 907-910. (25) Liu, M. J.; Tzou, K.; Gregory, R. V. Influence of the Doping Conditions on the Surface Energies of Conducting Polymers. Synth. Met. 1994, 63, 67-71.


15


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 16 of 18

(26) Patterson, A. L. The Scherrer Formula for X-Ray Particle Size Determination. Phys. Rev. 1939, 56, 978-982. (27) He, D.; Zeng, C.; Xu, C.; Cheng, N.; Li, H.; Mu, S.; Pan, M. Polyaniline-Functionalized Carbon Nanotube Supported Platinum Catalysts. Langmuir 2011, 27, 5582–5588. (28) Zengin, H.; Zhou, W.; Jin, J.; Czerw, R.; Smith, D. W., Jr.; Echegoyen, L.; Carroll, D. L.; Foulger, S. H.; Ballato. Carbon Nanotube Doped Polyaniline. J. Adv. Mater. 2002, 14, 14801483. (29) Bogdanović, U.; Pašti, I.; Ćirić-Marjanović, G.; Mitrić, M.; Ahrenkiel, S. P.; Vodnik, V. Interfacial Synthesis of Gold−Polyaniline Nanocomposite and Its Electrocatalytic Application. ACS Appl. Mater. Interfaces 2015, 7, 28393-28403 (30) Lu, Y.; Jiang, Y.; Wu, H.; Chen, W. Nano-PtPd Cubes on Graphene Exhibit Enhanced Activity and Durability in Methanol Electrooxidation after CO Stripping−Cleaning. J. Phys. Chem. C 2013, 117, 2926−2938. (31) Zhang, J.; Ma, L.; Gan, M.; Yang, F.; Fu, S.; Li, X. Well-Dispersed Platinum Nanoparticles Supported on Hierarchical Nitrogen-Doped Porous Hollow Carbon Spheres with Enhanced Activity and Stability for Methanol Electrooxidation. J. Power Sources 2015, 288, 42-52. (32) Chen, S.; Thota, S.; Wang, X.; Zhao, J. From Solid to Core@shell to Hollow Pt–Ag Nanocrystals: Thermally Controlled Surface Segregation to Enhance Catalytic Activity and Durability. J. Mater. Chem. A 2016, 4, 9038-9043. (33) Chen, S.; Wei, Z.; Qi, X.; Dong, L.; Guo, Y.; Wan, L.; Shao, Z.; Li, L. Nanostructured Polyaniline-Decorated Pt/C@PANI Core–Shell Catalyst with Enhanced Durability and Activity. J. Am. Chem. Soc. 2012, 134, 13252−13255. (34) Baker, C. O.; Shedd, B.; Tseng, R. J.; Martinez-Morales, A. A.; Ozkan, C. S.; Ozkan, M.; Yang, Y.; Kaner, R. B. Size Control of Gold Nanoparticles Grown on Polyaniline Nanofibers for Bistable Memory Devices. ACS Nano 2011, 5, 3469−3474.


16

Page 17 of 18

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(35) Goebel, A.; Lunkenheimer, K. Interfacial Tension of the Water/n-Alkane Interface. Langmuir 1997, 13, 369-372.


17


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 18 of 18

Table of Contents use only

Highly Catalytic Pt Nanoparticles Grown in Two-Dimensional Conducting Polymers at the Air-Water Interfaces

Kyoungwook Kim1, Hyungmin Ahn2, and Moon Jeong Park1,2*


18

Highly Catalytic Pt Nanoparticles Grown in Two ... - ACS Publications

Recommend Documents