Electrochemical deposited high-crystallinity vertical platinum nanosheets onto the carbon nanotubes directly grown on carbon paper for methanol oxidation Wen-Chien Fang a , Fu-Rong Chen a , Ming-Chi Tsai a , Huei-Yu Chou a , Hsuan-Chung Wu b , Chien-Kuo Hsieh b, ⁎ a Department of Engineering and System Science, National Tsing Hua University, Hsinchu, 30013, Taiwan, ROC b Department of Materials Engineering, Ming Chi University of Technology, New Taipei City, 24301, Taiwan, ROC abstract article info Article history: Received 17 August 2016 Revised 15 October 2016 Accepted in revised form 28 October 2016 Available online xxxx In this study, the high-crystallinity vertical platinum nanosheets (PtNSs) were deposited onto the carbon nano- tubes (CNTs) directly grown on the carbon paper (CP) as the PtNSs/CNTs/CP hybrid nanostructure to promote the electrocatlytic performance of methanol oxidation reaction (MOR). CNTs were initially synthesized on the carbon fibers of CP as catalyst supporting material by chemical vapor deposition method. Subsequently, PtNSs electrocatalysts with high activity were synthesized onto the CNTs surface by electrodeposition method. Scan- ning electron microscopy, high-resolution transmission electron microscopy and X-ray diffraction were employed to investrage the morphology and structural features of PtNSs/CNTs/CP. The Pt loading was examined by inductively coupled plasma mass spectrometry. The electronic structures of PtNSs were examined by X-ray photoelectron spectroscopy. The electrocatalytic properties were examined by Cyclic Voltammetry method. Our work suggests that PtNSs/CNTs/CP electrode could provide higher surface area with a lower Pt content and show better crystalline than Pt Black. The catalytic efficiency of prepared PtNSs/CNTs/CP electrode, as deter- mined by the electrochemical active surface area and the catalyst mass activity for the MOR, were 1.39 times and 2.95 times better than those of a commercial Pt-black catalyst, suggesting that PtNSs/CNTs/CP electrode might be a good candidate for catalyst of MOR. © 2016 Elsevier B.V. All rights reserved. Keywords: Carbon nanotubes Platinum nanosheets Electrochemical deposition Methanol oxidation 1. Introduction Direct methanol fuel cells (DMFCs) have attracted considerable attention as promising energy devices due to a series of advantages, in- cluding simple construction, the high energy density at low tempera- ture, the high durability, easy operation, and pollution-free production [1,2]. However, few obstacles were existed in realizing the commercial- ization of DMFCs, particularly the high expense of platinum (Pt) which is still recognized as the best catalyst for methanol oxidation reaction (MOR) [3]. Therefore, morphology controlled nanostructures of Pt were desired to achieve the high catalytic activities, such as Pt nanopar- ticles [4,5], Pt nanoflowers [6,7], Pt nanocubes [8,9], Pt nanowires [10, 11], and Pt nanodendritic [12]. In addition, the supporting material of catalyst has been recognized as one of the important factors in determining the electrochemical per- formance of the catalysts. Various supporting materials of catalysts have been studied, including conductive polymers [13–15], titanium oxide nanotubes [16–19], and carbon nanomaterials [20–22]. Among these supporting materials, carbon nanotubes (CNTs) have received a great deal of attention to replace conventional activated carbon black due to their structural tube features, superior electrical conductivity and high stability in electrochemical reaction [23–25]. In conventional process, the mixed catalyst bearing CNTs and polymer electrolytes were pasted onto diffusion layers such as carbon papers (CP) as a catalytic gas diffu- sion layer at the anode in fabricating a DMFC. However, the pasting pro- cess usually involved binder materials that induced the agglomerations, which not only decreased the active surface area but also provided a poor adhesion to the substrate. Directly growing CNTs on CP could avoid undesirable effect stemmed from pasting process mentioned above and improve the elec- trical conductivity between the catalyst supports and the diffusion layer, related researches for low temperature fuel cells were studied [26,27]. Hence, in this work, the CNTs were directly grown on CP as catalyst supporting material and following vertical Pt nanosheets (PtNSs) were electrodeposited on. The activities of the prepared catalytic electrodes were examined by half-cell tests in mixed methanol (CH 3 OH) and Surface & Coatings Technology xxx (2016) xxx–xxx ⁎ Corresponding author at: Department of Materials Engineering, Ming Chi University of Technology, 84 Gungjuan Rd., Taishan Dist., New Taipei City 24301, Taiwan. E-mail address: jack_hsieh@mail.mcut.edu.tw (C.-K. Hsieh). SCT-21731; No of Pages 6 http://dx.doi.org/10.1016/j.surfcoat.2016.10.086 0257-8972/© 2016 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Surface & Coatings Technology journal homepage: www.elsevier.com/locate/surfcoat Please cite this article as: W.-C. Fang, et al., Surf. Coat. Technol. (2016), http://dx.doi.org/10.1016/j.surfcoat.2016.10.086