以酚醛树脂作为碳源，采用嵌段共聚物模板法一步制备新型有序介孔碳化钨/碳（WC/C）纳米颗粒. WC/C颗粒的比表面积为414 m2·g-1，表面的平均孔径约为38 nm，处于介孔范围内（2 ~ 50 nm）. 通过调节树脂预聚时间以及碳化温度等条件制备出结构形貌较优的WC/C复合材料，并探讨了材料形成机理. 使用X射线衍射、扫描电镜、透射电镜及氮气吸脱附等方法表征了复合材料的结构. 将贵金属铂负载于WC/C表面制备得新电催化材料Pt-WC/C，使用循环伏安法和计时电流法对Pt-WC/C复合材料的电化学性能进行检测，并与商用碳载铂（Pt/C）材料进行对比. 测试结果发现，Pt-WC/C对甲醇的电催化活性以及稳定性等方面都表现出优于商用Pt/C材料的活性，这主要归功于碳化钨高度分散于碳表面.
At present, one of the major hurdles for commercialization of system with direct methanol fuel cell (DMFC) is still the requirement of a significant amount of platinum (Pt) catalyst to achieve an acceptable power density. Pt and Pt-based metals are expensive due to limited supplies. In order to find the catalyst alternative to the Pt metal, we selected tungsten carbide (WC) and its composites as the study object. We synthesized WC with carbon materials as the suitable support to modify the electronic structure and to increase the specific surface area of WC. In this study, tungsten carbide/carbon (WC/C) was prepared by block copolymer template synthesis method using resorcinol-formaldehyde resin (RF) as a carbon source. These novel, ordered, mesoporous WC/C nanocomposites showed high surface areas (414 m2·g-1) and appropriate pore-size (about 38 nm). The experimental conditions including the stirring time of phenol formaldehyde polymer and carburization temperature were systematically studied. The results indicated that the composites had optimized crystal phases and ordered arrangement of pores structures. The characteristics of WC/C composites were determined by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Brunauer-Emmet-Teller gas adsorption. The Pt nanoparticles were uniformly distributed on WC/C and a new electrocatalyst of Pt-WC/C was prepared by microwave-assisted (MW) polyol method. The electro-catalytic performances of the as-prepared Pt-WC/C and commercial carbon-supported Pt (Pt/C) toward methanol oxidation were compared by cyclic voltammetry and chronoamperometry. It was found that the Pt-WC/C exhibited higher catalytic activity for methanol oxidation than commercial Pt/C catalyst. Especially, the Pt-WC/C achieved the long-term stability which was attributed to the high dispersion of WC with smaller sizes on the surface of carbon.
[1]Chandrasekaran K, Wass J C, Boclcris J O. The potential dependence of intermediates in methanol oxidation observed in the steady state by FTIR spectroscopy[J]. Journal of the Electrochemical Society, 1990, 137(2): 518-524.
[2]Lang X L(郎小玲), Shi M Q(施梅勤), Jiang Y K(江叶坤), et al. Influence of pretreatment on electrocatalytic property for methanol oxidation of PtRu/WC[J]. Journal of Electrochemistry(电化学), 2013, 19(3): 1-5.
[3]Qi L(戚利), Yin Y(殷瑛), Tu W G(涂文广), et al. Preparation of Pt-TiO2/Graphene composites with high catalytic activity towards methanol oxidation and oxygen reduction reaction[J]. Journal of Electrochemistry(电化学), 2014, 20(4): 337-381.
[4]Gao H L(高海丽), Liao S J(廖世军), Zeng J H(曾建皇), et al. Preparation and characterization of platinum-decorated Ru/C catalyst with high performance and superior poison tolerance[J]. Acta Physico Chimica Sinica(物理化学学报), 2010, 26(12): 3193-3198.
[5]Jeon M K, Daimon H, Lee K R. CO tolerant Pt/WC methanol electro-oxidation catalyst[J]. Electrochemistry Communications, 2007, 9(11): 2692-2695.
[6]Ganesan R, Ham D J, Lee J S. Platinized mesoporous tungsten carbide for electrochemical methanol oxidation[J]. Electrochemistry Communications, 2007, 9(10): 2576-2579.
[7]Ma C A(马淳安), Yu B(俞 彬), Shi M Q(施梅勤), et al. Preparation and electrocatalytic activity of the Pt/WC/TiO2 composites[J]. Journal of Electrochemistry(电化学), 2011, 17(2): 149-154.
[8]Ma C A, Brandon N, Li G H. Preparation and formation mechanism of hollow microspherical tungsten carbide with mesoporosity[J]. The Journal Physical Chemistry C, 2007, 111(26): 9504-9508.
[9]Ma C A, Sheng J F, Brandon N, et al. Preparation of tungsten carbide-supported nano platinum catalyst and its electrocatalytic activity for hydrogen evolution[J]. International Journal of Hydrogen Energy, 2007, 32(14): 2824-2829.
[10]Houston J E, Laramore G E, Park R L. Surface electronic properties of tungsten, tungsten carbide, and platinum[J]. Science, 1974, 185(4147): 258-260.
[11]Mcintyre D R, Burstein G T, Vossen A. Effect of carbon monoxide on the electrooxidation of hydrogen by tungsten carbide[J]. Journal of Power Sources, 2002, 107(1): 67-73.
[12]Li G H(李国华), Tian W(田伟), Tang J Y(汤俊艳), et al. Preparation and electrocatalytic property for methanol oxidation of WC/CNT nanocomposite[J]. Acta Physico Chimica Sinica(物理化学学报), 2007, 23(9): 1370-1374.
[13]Xia L Y, Zhang M Q, Rong M Z, et al. An easy soft-template route to synthesis of wormhole-like mesoporous tungsten carbide/carbon composites[J]. Composites Science and Technology, 2012, 72(14): 1651-1655.
[14]Zhou J H, He J P, Ji Y J, et al. CTAB assisted microwave synthesis of ordered mesoporous carbon supported Pt nanoparticles for hydrogen electro-oxidation[J]. Electrochimica Acta, 2007, 52(14): 4691-4695.
[15]Ciesla U, Schuth F. Ordered mesoporous materials[J]. Microporous and Mesoporous Materials, 1999, 27(2/3): 131-149.
[16]Corma A. From microporous to mesoporous molecular sieve materials and their use in catalysis[J]. Chemical Reviews, 1997, 97(6): 2373-2420.
[17]Wu Z X, Yang Y X, Gu D, et al. Silica-templated synthesis of ordered mesoporous tungsten carbide/graphitic carbon composites with nanocrystalline walls and high surface areas via a temperature-programmed carburization route[J]. Small, 2009, 5(23): 2738-2749.
[18]Piquemal J Y, Potvin C, Manoli J M, et al. Synthesis and characterization of highly dispersed molybdenum carbides in mesoporous silica[J]. Catalysis Letters, 2004, 92(3/4): 189-195.
[19]Cahen S, Furdin G, Marche J F, et al. Synthesis and characterization of carbon-supported nanoparticles for catalytic applications[J]. Carbon, 2008, 46(3): 511-517.
[20]Shi X L, Yang H, Sun P, et al. Synthesis of multi-walled carbon nanotube-tungsten carbide composites by the reduction and carbonization process[J]. Carbon, 2007, 45(9): 1735-1742.
[21]Li G H, Ma C A, Tang J Y, et al. Preparation and electrocatalytic property of WC/carbon nanotube composite[J]. Electrochimica Acta, 2007, 52(5): 2018-2023.
[22]Wang H(王辉), Zhang H(张慧), Wang A Q(王爱琴), et al. Preparation of metal carbide imbedded ordered mesoporous carbon and its catalytic properties for N2H4 decomposition[J]. Chinese Journal of Catalysis(催化学报), 2010, 31(9): 1172-1176.
[23]Shi M Q(施梅勤), Lang X L(郎小玲), Ma C A(马淳安), et al. Microwave heated synthesis of Pt/WC and its electrocatalytic activity for methanol electrooxidation[J]. Acta Chimica Sinica(化学学报), 2011, 69(9): 1029-1034.
[24]Zhao D Y, Feng J, Huo Q S, et al. Triblock copolymer syntheses of mesoporous silica with periodic 50 to 300 angstrom porcess[J]. Science, 1998, 279(5350): 548-552.
