A new inclusion complex thiourea with tetrabutylammonium salicylate and water, 4(C4H9)4N+C7H5O3 ?4(NH2)2CS?2H2O, has been prepared and characterized by X-ray crystallo- graphy. Crystal data: MoKα radiation, triclin...A new inclusion complex thiourea with tetrabutylammonium salicylate and water, 4(C4H9)4N+C7H5O3 ?4(NH2)2CS?2H2O, has been prepared and characterized by X-ray crystallo- graphy. Crystal data: MoKα radiation, triclinic, space group P1 with a = 13.505(5), b = 13.645(5), c = 30.720(10) ?, α = 92.872(7), β = 92.329(7), γ = 92.538(7)°, V = 5643.0(3) ?3, C96H184N12O14S4, Mr = 1858.79, Z = 2, Dc = 1.094 g/cm3, μ = 0.143 mm-1, F(000) = 2040, R = 0.0694 and wR = 0.1282 for 4303 observed reflections with I > 2σ(I). There are three different layer type host-lattices in the crystal structure of the title compound. All of them are formed by [(NH2)2CS·(C7H5O3 )]4 tetramers, but water molecules are located between tetramers and link them by hydrogen bonds to generate ribbons at c = 0 and 1/2, and isolated tetramers are arranged side by side at c = 1/4. The tetrabutylammonium cations are sandwiched between puckered layers.展开更多
基金Supported by the National Natural Science Foundation of China (29973005) Natural Science Foundation of Beijing (2042013)
文摘A new inclusion complex thiourea with tetrabutylammonium salicylate and water, 4(C4H9)4N+C7H5O3 ?4(NH2)2CS?2H2O, has been prepared and characterized by X-ray crystallo- graphy. Crystal data: MoKα radiation, triclinic, space group P1 with a = 13.505(5), b = 13.645(5), c = 30.720(10) ?, α = 92.872(7), β = 92.329(7), γ = 92.538(7)°, V = 5643.0(3) ?3, C96H184N12O14S4, Mr = 1858.79, Z = 2, Dc = 1.094 g/cm3, μ = 0.143 mm-1, F(000) = 2040, R = 0.0694 and wR = 0.1282 for 4303 observed reflections with I > 2σ(I). There are three different layer type host-lattices in the crystal structure of the title compound. All of them are formed by [(NH2)2CS·(C7H5O3 )]4 tetramers, but water molecules are located between tetramers and link them by hydrogen bonds to generate ribbons at c = 0 and 1/2, and isolated tetramers are arranged side by side at c = 1/4. The tetrabutylammonium cations are sandwiched between puckered layers.
基金supported by the International Science & Technology Cooperation Program of China(2010DFB63680)the National Natural Science Foundation of China(21376220)Zhejiang Provincial Natural Science Foundation of China(LY16B060009,LY12B03008)~~
文摘直接甲醇燃料电池(DMFCs)作为一种环境友好、高效的新能源,对解决世界目前面临的"能源危机"与"环境危机"这两大问题有着至关重要的意义,具有较广阔的应用前景.目前,甲醇氧化催化剂仍然以Pt基为主,但是Pt价格昂贵,且容易受甲醇氧化中间产物的毒化,从而影响了DMFCs的商业化进程.碳化钨(WC)作为非贵金属催化剂,在催化方面具有类铂的性能.在WC上负载适量的Pt,可以通过两者的协同效应加强催化剂的抗CO中毒能力.但是,由于WC的导电性能不佳,比表面积较小,因此寻找合适的载体显得尤为必要.在碳载体中,石墨烯(RGO)具有优良的导电性以及独特的片层结构,是电催化剂的理想载体.以RGO为载体,WC为插层物质制备的WC-RGO插层复合物具有化学稳定性好、电导率高且电化学活性面积大等优势.但是,由于石墨烯表面光滑且呈惰性,同时使用传统的碳化方法制备的碳化钨颗粒较大,因此,制备较小颗粒且分散均匀的WC-RGO插层复合物具有较大难度.一般以偏钨酸铵和氧化石墨烯(GO)为前驱体制备WC-RGO插层复合物,但是由于偏钨酸根和GO都带负电,因此不能成功地将偏钨酸根引入到石墨烯的片层结构中,造成WC-RGO插层复合物组装上的困难.本文采用硫脲成功地合成了具有高分散性WC纳米颗粒插层在少层RGO里的WC-RGO插层复合物.硫脲((NH_2)_2CS)作为阴离子接受器,具有较强的结合阴离子形成稳定复合物的能力,同时它也是合成具有片层结构的过渡金属硫化物的原料之一.因此在WC-RGO插层复合物组装过程中,硫脲既作为锚定及诱导剂,又是制备片层二硫化钨(WS_2)的硫源.材料具体制备方法如下:首先利用浸渍法,将偏钨酸根阴离子([H_2W_(12)O_(40)]^(6-))牵引到(NH_2)_2CS改性过的GO上形成[H_2W_(12)O_(40)]^(6-)-(NH_2)_2CS-GO前驱体;然后将前驱体放入管式炉中还原碳化,前驱体先反应生成WS_2;由于WS_2自身的2D片层结构,反应中可以得到WS_2-RGO插层复合物,接着原位碳化生成WC-RGO插层复合物.碳化钨-石墨烯负载铂电催化剂(Pt/WC-RGO)通过微波辅助法制得,并采用X射线衍射、扫描电子显微镜、透射电子显微镜及激光拉曼光谱等手段对其结构与形貌进行了表征.结果显示,在WC-RGO插层复合物中,WC的平均粒径为1.5 nm,RGO的层数约为5层.在甲醇电氧化反应中,相比于商用Pt/C催化剂,Pt/WC-RGO插层复合物催化剂具有更高的电化学活性面积(ECSA)和较高的峰电流密度(246.1 m^2/g Pt,1364.7 m A/mg Pt),分别是Pt/C的3.66和4.77倍.我们分别利用CO溶出伏安法、计时电流法及加速耐久性试验法验证了Pt/WC-RGO催化剂优秀的抗CO中毒能力及稳定性.Pt/WC-RGO催化剂特殊的插层结构,在增加WC与Pt接触机会以加强协同作用的同时,促进了催化过程中质量及电荷的转移,因而具有比Pt/C更高的催化活性.可见,通过制备WC-RGO插层复合物可降低Pt用量,从而大大地降低燃料电池中电催化剂的成本.同时,我们使用的是一种高效,可大批量生产纳米材料的方法,有助于催化剂的商业化.
