催化学报 ›› 2017, Vol. 38 ›› Issue (6): 1028-1037.DOI: 10.1016/S1872-2067(17)62830-4

• 论文 • 上一篇    下一篇

高分散超薄二硫化钼/硫、氮共掺碳复合材料的电催化析氢性能

滑世新a, 曲丹a,b,c, 安丽a, 席广成d, 陈戈a, 李钒a, 周志军e, 孙再成a   

  1. a. 北京工业大学环境与能源工程学院, 化学与化学工程系, 绿色催化与分离北京市重点实验室, 北京 100124;
    b. 中国科学院长春光学精密机械与物理研究所, 发光学及应用国家重点实验室, 吉林长春 133033;
    c. 中国科学院大学, 北京 100049;
    d. 中国检验检疫科学研究院, 纳米材料与产品研究中心, 北京 100000;
    e. 中国工程物理研究院核物理与化学研究所, 四川绵阳 621000
  • 收稿日期:2017-02-14 修回日期:2017-03-18 出版日期:2017-06-18 发布日期:2017-06-08
  • 通讯作者: 孙再成
  • 基金资助:

    国家自然科学基金(21671011);北京市高层次人才计划

Highly dispersed few-layer MoS2 nanosheets on S, N co-doped carbon for electrocatalytic H2 production

Shixin Huaa, Dan Qua,b,c, Li Ana, Guangcheng Xid, Ge Chena, Fan Lia, Zhijun Zhoue, Zaicheng Suna   

  1. a. Beijing Key Laboratory of Green Catalysis and Separation, College of Environmental and Energy Engineering, Beijing University of Technology, Chaoyang Distrcti, Beijing 100124, China;
    b. State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics, and Physics, Chinese Academy of Sciences, Changchun 130033, Jilin, China;
    c. University of Chinese Academy of Sciences, Beijing 100049, China;
    d. Nanomaterials and Nanoproducts Research Center, Chinese Academy of Inspection and Quarantine, Beijing 100000, China;
    e. Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621000, Sichuan, China
  • Received:2017-02-14 Revised:2017-03-18 Online:2017-06-18 Published:2017-06-08
  • Supported by:

    This work is supported by the National Natural Science Foundation of China (21671011) and Beijing High-Level Talent program

摘要:

氢气是一种清洁可再生能源,有望在未来替代化石燃料成为最主要的能源物质. 电催化析氢技术是最有效的产氢途径之一. 目前,电催化析氢催化剂主要是贵金属铂,由于其昂贵的价格限制了它的大规模应用. 所以在不减少催化剂活性的前提下尽量减少贵金属的使用或者寻找替代物质,降低成本是工业化大规模使用析氢反应(HER)催化剂的前提. 二硫化钼基催化剂因其价格低廉、资源丰富且具有优异的催化析氢性能而引起研究者的广泛关注. 实验和理论研究都证明了二硫化钼的催化性能和其催化活性位点有关. 所以,开发一种具有丰富的活性位点、良好的导电性的二硫化钼基催化剂可以获得高的产氢性能和良好的稳定性. 因此,对于提高MoS2的电催化析氢性能的研究主要集中于增加MoS2暴露活性位点的个数和导电性. 然而,二硫化钼层与层之间的相互作用可能导致其发生聚集,较低的导电率都有可能降低它的电催化活性.
我们通过水热的方法直接制备出了固体的硫、氮共掺杂的、具有石墨化结构的碳复合材料(SNC). 将钼酸钠加入到反应中后,多钼酸盐通过化学交互作用均匀地嵌入、分散到SNC中. 经高温处理后,SNC放出S2-,多钼酸盐结合S2-生成二硫化钼. SNC有效地防止了二硫化钼聚集成大的颗粒. 我们成功地制备出具有较好析氢性能的、高度分散于SNC中的二硫化钼纳米片. 通过透射电子显微镜(TEM)、扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)、元素分析、X射线光电子能谱(XPS)等测试手段对材料进行了表征,通过电催化析氢、电化学阻抗以及稳定性测试等手段研究了其电催化性能.
由MoS2/SNC-900-12h的TEM图片可以看出,二硫化钼纳米片高度分散于碳复合材料中,且层数只有一到几层,暴露出了更多的催化活性位点. 拉曼光谱图的D带(1341 cm-1)和G带(1584 cm-1)体现出了材料具有较好的石墨化结构,提高了材料的导电性. XPS C 1s谱图中存在C-S和C-N键,S 2p谱图中存在C-S-C、C=S和C-SOx-C键,N 1s谱图中存在吡啶氮和石墨氮,结合元素分析,说明该碳材料确为硫氮共掺杂的碳;Mo谱测试显示出Mo 3d5/2 (229.4 eV)和Mo 3d3/2 (232.6 eV),证明了二硫化钼成功地嵌入到了碳材料中. 电化学性能表征显示MoS2/SNC-900-12h在H2SO4溶液(0.5 mol/L)中展现出较低的起始电位(115 mV)以及低的过电位(237 mV). 电化学阻抗测试显示在H2SO4溶液(0.5 mol/L)中过电位为-0.2 V (vs. RHE)时Rct只有124 W. 此外,在-0.3-0 V (vs. RHE)下,经5000圈稳定性测试后性能只有约2.6% (10 mA/cm2)的衰减,说明MoS2/SNC-900-12h同样具有优异的电化学稳定性.

关键词: 二硫化钼纳米片, 硫、氮共掺杂的碳, 电催化析氢, 复合材料, 析氢反应

Abstract:

Ultrathin small MoS2 nanosheets exhibit a higher electrocatalytic activity for the hydrogen evolution reaction. However, strong interactions between MoS2 layers may result in aggregation; together with the low conductivity of MoS2, this may lower its electrocatalytic activity. In this paper we present a method that we developed to directly produce solid S, N co-doped carbon (SNC) with a graphite structure and multiple surface groups through a hydrothermal route. When Na2MoO4 was added to the reaction, polymolybdate could be anchored into the carbon materials via a chemical interaction that helps polymolybdate disperse uniformly into the SNC. After a high temperature treatment, polymolybdate transformed into MoS2 at 800 ℃ for 6 h in a N2 atmosphere at a heating rate of 5 ℃/min, owing to S2- being released from the SNC during the treatment (denoted as MoS2/SNC-800-6h). The SNC effectively prevents MoS2 from aggregating into large particles, and we successfully prepared highly dispersed MoS2 in the SNC matrix. Electrochemical characterizations indicate that MoS2/SNC-900-12h exhibits a low onset potential of 115 mV and a low overpotential of 237 mV at a current density of 10 mA/cm2. Furthermore, MoS2/SNC-900-12h also had an excellent stability with only ~2.6% decay at a current density of 10 mA/cm2 after 5000 test cycles.

Key words: MoS2 nanosheet, S, N co-doped carbon, Electrocatalytic hydrogen production, Composite, Hydrogen evolution reaction