Subscriber access provided by ORTA DOGU TEKNIK UNIVERSITESI KUTUPHANESI
Article
In-situ growth of Prussian blue nanostuctures at reduced graphene oxide as a modified platinum electrode for synergistic methanol oxidation Shanmugam Manivannan, Inhak Kang , and Kyuwon Kim Langmuir, Just Accepted Manuscript • DOI: 10.1021/acs.langmuir.5b04278 • Publication Date (Web): 25 Jan 2016 Downloaded from http://pubs.acs.org on January 26, 2016
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.
Langmuir 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 27
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
Langmuir
In-situ growth of Prussian blue nanostructures at reduced graphene oxide as a modified platinum electrode for synergistic methanol oxidation Shanmugam Manivannan, Inhak Kang and Kyuwon Kim* Electrochemistry Laboratory for Sensors & Energy, Department of Chemistry, Incheon National University, Incheon 406-772, Republic of Korea. *E-mail:
[email protected] Abstract: Herein, we report a facile synthetic strategy for the in-situ growth of Prussian blue nanostructures (PB NSs) at the amine functionalized silicate sol–gel matrix (TPDT)–RGO composite via the electrostatic interaction. Subsequently, Pt nanostructures are electrodeposited onto the preformed ITO/TPDT–RGO–PB electrode to prepare the RGO/PB/Pt catalyst. The significance of the present method is that the PB NSs are in-situ grown by inter-connecting the RGO layers, led to 3D cage-like porous nanostructure. The modified electrodes are characterized by FESEM, EDAX, XRD, XPS and electrochemical techniques. The RGO/PB/Pt catalyst exhibits synergistic electrocatalytic activity and high stability towards methanol oxidation. The porous nature of the TPDT and PB, and unique electron transfer mediating behavior of PB integrated with RGO in the presence of Pt nanostructures, facilitated synergistic electrocatalytic activity for methanol oxidation. Keywords: Electrocatalysis, Methanol oxidation, Platinum, Prussian blue, Reduced Graphene Oxide, Sol–Gel Matrix.
1|Page ACS Paragon Plus Environment
Langmuir
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
1.
Introduction Prussian blue (PB) is widely used as the mediator in electrochemical biosensors1–5 and
usually referred to as an artificial peroxidase for biologically important electrochemical studies due to its high electrocatalytic activity, stability, porosity and selectivity towards analytes at lower applied potentials.6–9 In recent years, extensive studies on PB based nanocomposites in many fields especially electrochromic devices,10–12 catalysis and sensors has been undertaken.13–15 Among the numerous applications, fabrication of a device for practical applications based on PB is particularly attractive. For such devices, stable and an active support is required to immobilize the PB nanoparticles (NPs). PB is usually synthesized by mixing of either Fe3+ with the [Fe(II)(CN)6]4- or Fe2+ with the [Fe(III)(CN)6]3- (FC), giving an insoluble dark blue colloid. The electrodeposition of PB on various substrates from the electrolyte containing both anions and cations in the presence of excess supporting electrolytes were also reported.16–18 However, the aforementioned reaction are too fast because of the small solubility product constant of PB (Ksp = 3.3×10−41), thus the morphology and the size of PB cannot be easily controlled.19 The adsorption of corresponding anions ([Fe(II)(CN)6]4- or FC) followed by cations (Fe3+ or Fe2+) at the suitable solid support leading to the in-situ growth of the PB was also reported.20–22 Graphene (GR), due to its ability to promote the electron-transfer reactions has become an ideal material for electrochemistry because of its large 2D electrical conductivity, large surface area and low cost.23 To explore the functionalities of GR, much attention has been paid to fabricating GR nanocomposites. Platinum (Pt) and PB nanostructures (NSs) have been anchored on the surface of GR, which can be applicable for catalysis and sensor applications. Thus far, many GR–PB13–15,24 GR–Pt25–27 and GR–PB–Pt28 nanocomposites have been used in catalysis and sensor studies. For instance, Wang et al.28 studied the GR–PB–Pt nanocomposite as electrocatalytic material for methanol oxidation reaction (MOR), observed better performance than GR–Pt nanocomposite. On the other hand, the depletion of conventional fossil fuel reserves and rapid growth of environmental 2|Page ACS Paragon Plus Environment
Page 2 of 27
Page 3 of 27
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
Langmuir
pollution has led to the search for alternative power sources29,30 such as direct methanol fuel cells (DMFCs) which can convert the chemical energy of the methanol to electrical energy and environment friendly.31,32 Because of the high cost and CO poisoning, polycrystalline Pt electrodes are limited to use in DMFCs. Hence, hybridization of different materials with low cost, controlled compositions and morphologies organized in films with Pt at the nanoscale level has attracted immense attention because of the new properties that have emerged in the resulting nanocomposite. For this purpose, economical cost and facile preparation of reduced graphene oxide (RGO) and PB nanocomposites with exceptional electrocatalytic properties is still significant. Herein, we studied the in-situ growth of PB nanostructures (NSs) at the amine functionalized silicate sol–gel matrix (TPDT)–RGO composite through the electrostatic interaction between the surface absorbed FC and Fe2+ ions. Subsequently, Pt NPs are electrodeposited to prepare RGO– PB/Pt catalyst. The as-prepared RGO–PB/Pt catalyst has synergistic effect on its electrocatalytic activity toward MOR. The growth and stability concerning of PB NSs at the RGO surface is considerably addressed. Furthermore, PB NSs prepared by electrochemical deposition and coprecipitation do not provide a precise control of the structure. The growth of PB NSs via electrostatic interaction overcomes this problem and allows for the preparation of dense and uniform PB NSs. The porous nature of both TPDT and PB NSs and intrinsic catalytic property of PB NSs interconnecting the RGO and Pt NPs leads to such synergistic electrocatalytic effect. 2.
Experimental Section
2. 1.
Materials and Methods Graphite (powder
